https://doi.org/10.52131/jmps.2020.0101.0002 12 journal of materials and physical sciences volume 1, number 1, 2020, pages 12 18 journal homepage: https://journals.internationalrasd.org/index.php/jmps synthesize and characterization of ca substituted co-zn ferrites by micro-emulsion technique zeshan mehboob1, muhammad shahzad shifa2*, humaira akhtar shahia1, muhammad hashim2 1 department of physics, govt college university faisalabad, allama iqbal road, faisalabad, pakistan 2 institute of physics, the islamia university of bahawalpur, bahawalpur, pakistan article info abstract article history: received: april 24, 2020 revised: june 04, 2020 accepted: june 28, 2020 available online: june 30, 2020 co-zn ferrites have great magneto-striction, high corrosion resistivity and excellent chemical stability. we can control the ferromagnetic properties and paramagnetic properties of cozn ferrites by changing its particle distribution and particle size. there are different types of techniques are available to synthesis co-zn ferrites like co-precipitation, sol gel and autocombustion method etc. in this research, we will synthesize co-zn ferrites by micro-emulsion technique and substitute ca in it with different composition. xrd results showed that samples were in single phase ferrite. particle size was between the ranges of 34-14nm. average lattice constant were 8.118.18å. ft-ir confirm the results obtained by xrd. sem confirm the morphology of the samples and its grain size. grain size decreased with increased of the concentration of ca in co0.6-xzn0.4caxfe2o4. tga results were found in agreement with previous literatures. keywords: co-zn ferrite spinel ferrites micro-emulsion xrd ftir sem tga © 2020 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: shahzad.shifa@gmail.com 1. introduction ferrites have gained immense significance in current moment. ferrites are comparatively steady, low cost and a wide range in different logical applications in mri, sensors, magnetic recording and so forth. so, it is concluded that any other magnetic materials cannot replace by spinal ferrites. these days, these materials are largely synthesized in nanometric scale for new and enhanced properties. fe2o3 and metallic oxides are the main constituents of the ferrites (raghasudha, ravinder, & veerasomaiah, 2013). the value of ferrite material has been known to mankind for many centuries. ferrites were very famous in chinese nation in early 12th century in form of compass for navigation purpose. ferrites have high electric resistivity, less eddy current, mediocre permittivity and high saturation magnetization ms (li, yang, bao, meng, & lou, 2013). basically, ferrites are magnetic oxides and there is no such material that can replace ferrites due to high range properties that it’s have. accordingly, ferrites are exclusive magnetic materials which locate applications in approximately all fields. ferrite’s have great electrical and magnetic properties; that’s way they have great importance in technological devices (arulmurugan, jeyadevan, vaidyanathan, & sendhilnathan, 2005). ferrites can be used in magnetic recording, computer technology, used as permanent magnets, transformer cores and memory chips etc (zhang, zhong, yu, liu, & zeng, 2009). there are two types of ferrites in general named as soft (spinel) ferrites and hard (hexagonal) ferrites. https://journals.internationalrasd.org/index.php/jmps mailto:shahzad.shifa@gmail.com zeshan mehboob, muhammad shahzad shifa, humaira akhtar shahia, muhammad hashim 13 2. method and material ca doped co-zn ferrite were prepared by the micro-emulsion technique by using, fe (no3)2. 9h2o, ca (no3)2. 6h2o, zn (no3).6h2o, co (no3).6h2o, cetyl-trimethl-ammonium bromide (ctab), as raw materials. firstly, all solutions were prepared according to calculated volume in distilled water. ctab will mix up in the solution. 6 grams of naoh was dissolved in appropriate amounts (50ml) of distilled water and mixed it in the solution to obtained ph value near to 12. solution stirred constantly by using magnetic stir and maintained temperature about 50oc-55oc. after 3h stirring, solution becomes a homogeneous solution. by washing solution with distilled water reduced solution ph to value 7. after that, solution was dried into oven at temperature 85oc for 24h to get dried powder form. after grinding the dry solution, very fine and brown colored ca doped co-zn ferrite was synthesized. to study its magnetic and structural properties, samples were annealed at 900oc for 5h. after that temperature slowly down up to room temperature and samples again grind to get more structure powder (gilani et al., 2017). figure 1: solution stirred constantly figure 2: homogeneous solution after string to study the crystal size and it phases, generally xrd, fourier transform infrared (ft-ir) spectroscopy, thermo-geometry analysis (tga), scanning electron microscope (sem) is used. due to extremely outstanding electrical and magnetic properties, cubic ferrites (which are synthesized at nano scale) intensively investigated in these recent years. these cubic ferrites are using in different areas of daily life, for example: recording disks or tapes, magnetic devices, active components of ferro-fluids and microwave absorbers. the purpose to synthesized the ca doped co-zn ferrite is that to study it effect on different properties of co-zn ferrites like corrosion resistivity, anisotropy, magneto-optical, magneto-crystalline and chemical stability (he, 2011). now a days, different techniques are using to synthesized ca doped co-zn ferrite. however, we synthesis ca doped co-zn ferrite is limited through micro-emulsion technique. in this research, we try to synthesis ca doped co-zn ferrite by micro-emulsion technique and study the effect on it morphology, magnetic and electrical properties. https://en.wikipedia.org/wiki/scanning_electron_microscope journal of materials and physical sciences 1(1), 2020 14 figure 3: dried solution into oven at temperature 85oc 3. result and discussion of structural properties in our research experiment, we try to synthesize ca doped co-zn ferrite by microemulsion technique using cetyl-trimethl-ammonium bromide (ctab) as a template. after making solution of ca doped co-zn ferrite, samples are dry at 85oc in drying oven and annealed in furnace at 850oc for 5h. after xrd characterization, following pattern are obtained (gilani et al., 2017). the xrd pattern of ca doped co-zn ferrite co0.6-x-zn0.4 cax fe2o4 (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5) shows that samples are in the single phase and have spinel structure without any impurity. diffraction peaks (220), (311), (422) and (511) are clear verification of spinel ferrite (kumar, singh, mandal, & kotnala, 2015). the d spacing for each peak is record by automatic software (match; version: 3.4.2, build96), then lattice parameter (a) is calculate from following relation: a= dhkl (h2+k2+l2)1/2 (1) results show that lattice constant always depends on the concentration of ca after doping in co-zn ferrite. in co0.6-x-zn0.4 cax fe2o4, lattice constant increased from 8.41 to 8.53 at x=0.1-0.4 but decreased to8.42 at x=0.5. zeshan mehboob, muhammad shahzad shifa, humaira akhtar shahia, muhammad hashim 15 figure 4: xrd patterns for all samples figure 4 shows co0.6-x-zn0.4 cax fe2o4 xrd patterns. from graph, it is confirms the following peaks for samples in phase with some extra peaks; (220), (311), (422) and (511) and also confirms their cubic spinal structural formation. from experiment, we find alter plane distance d, lattice constant (a) unit (ao) and volume of the unit cell (ao)3 and particle size from full width half maxima (fwhd) method (arulmurugan et al., 2005; nazim et al., 2016; urcia-romero, perales-pérez, & gutiérrez, 2010). journal of materials and physical sciences 1(1), 2020 16 results shows that with the increase of the concentration of ca in co-zn ferrite, the lattice constant increase from 8.11-8.18 ao and particle size decreased from 34-14nm with increase of ca concentration. (a) (b) (c) (d) (e) (f) figure 5: ftir graphs for all samples from 450cm-1-4000cm-1 figure 5 shows ftir spectra for ca doped co-zn ferrite at room temperature in the range of 450-4000cm-1respectively. the obtained result confirms the cubic structure. results show two bands v1 and v2 that referred to the intrinsic vibration of tetra-hedral and octa-hedral complexes. the bond vibration between tetra-hedral metal ion (o-mtetra) and oxygen ion is assigned for v1. the bond vibration between octa-hedral ion (o-mocta) and oxygen is assigned for v2. co0.5-zn0.4 ca0.1 fe2o4 co0.3-zn0.4 ca0.3 fe2o4 zeshan mehboob, muhammad shahzad shifa, humaira akhtar shahia, muhammad hashim 17 co0.1-zn0.4 ca0.5 fe2o4 figure 6: sem spectra for ca doped co-zn ferrite the sem images clearly show the materials are small size in nano-region (sathishkumar, venkataraju, & sivakumar, 2011). sem results shows that the crystal is spinal ferrite. co0.6-zn0.4 fe2o4 co0.4-zn0.4 ca0.2 fe2o4 co0.2-zn0.4ca0.4 fe2o4 (a) (b) (c) figure 7: tga results for all samples from temperature to 1000oc figure 7 shows the tga results for co0.6-zn0.4 fe2o4, co0.4-zn0.4 ca0.2 fe2o4 and co0.1zn0.4 ca0.5 fe2o4 nano ferrites from room temperature to 1000oc. weight loss is gradually decreased from 117oc-231oc for co0.6-zn0.4 fe2o4 and a sharp weight loss is in the region of 233-346 oc and 669-732 oc. for co0.4-zn0.4 ca0.2 fe2o4, gradually weight loss region is between 117-212 oc and sharp weight loss region is 223-450 oc and 611-729 oc. for co0.1zn0.4 ca0.5 fe2o4, gradually weight loss region is between 107-233 oc and sharp weight loss region is 223-450 oc and 644-701 oc (arulmurugan et al., 2005; nazim et al., 2016). 4. conclusion in our research work, we investigated that ca doped co-zn ferrite (co0.6-xzn0.4caxfe2o4 where x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5) nanoscale particles were synthesized by micro-emulsion method where ctab was used as template. all samples were sintered at journal of materials and physical sciences 1(1), 2020 18 850oc. the following characterization were used to study the samples; xrd, ft-ir, sem and tga. xrd results showed that samples were in single phase ferrite. crystalline size was between the ranges of 34-14nm. average lattice constant were 8.11-8.18ao. ft-ir conform the results obtained by xrd. sem conform the morphology of the samples and its grain size. grain size decreased with increased of the concentration of ca in co0.6-x-zn0.caxfe2o4. tga results were found in agreement with previous literatures (nazim et al., 2016). reference arulmurugan, r., jeyadevan, b., vaidyanathan, g., & sendhilnathan, s. (2005). effect of zinc substitution on co–zn and mn–zn ferrite nanoparticles prepared by coprecipitation. journal of magnetism and magnetic materials, 288, 470-477. doi:https://doi.org/10.1016/j.jmmm.2004.09.138 gilani, z. a., anjum, m. n., shifa, s., khan, h. u. h., asghara, j., usmani, m., . . . warsi, m. (2017). morphological and magnetic behavior of neodymium doped lini0. 5fe2o4 nanocrystalline ferrites prepared via microemulsion technique. j. nanomater. biostruct, 12, 223-228. he, h. (2011). magnetic properties of co0. 5zn0. 5fe2o4 nanoparticles synthesized by a template-assisted hydrothermal method. journal of nanotechnology, 2011. kumar, s., singh, v., mandal, u. k., & kotnala, r. k. (2015). nanocrystalline co0.5zn0.5fe2o4 ferrite: synthesis, characterization and study of their magnetic behavior at different temperatures. inorganica chimica acta, 428, 21-26. doi:https://doi.org/10.1016/j.ica.2015.01.014 li, x., yang, w., bao, d., meng, x., & lou, b. (2013). influence of ca substitution on the microstructure and magnetic properties of srlaco ferrite. journal of magnetism and magnetic materials, 329, 1-5. doi:https://doi.org/10.1016/j.jmmm.2012.10.004 nazim, s., kousar, t., shahid, m., khan, m. a., nasar, g., sher, m., & warsi, m. f. (2016). new graphene-coxzn1−xfe2o4 nano-heterostructures: magnetically separable visible light photocatalytic materials. ceramics international, 42(6), 7647-7654. doi:https://doi.org/10.1016/j.ceramint.2016.01.177 raghasudha, m., ravinder, d., & veerasomaiah, p. (2013). effect of cr substitution on magnetic properties of mg nanoferrites synthesized by citrate-gel auto combustion method. journal of chemistry, 2013, 804042. doi:10.1155/2013/804042 sathishkumar, g., venkataraju, c., & sivakumar, k. (2011). effect of nickel on the structural and magnetic properties of nano structured coznfe2o4. journal of materials science: materials in electronics, 22(11), 1715. doi:10.1007/s10854-0110351-8 urcia-romero, s., perales-pérez, o., & gutiérrez, g. (2010). effect of dy-doping on the structural and magnetic properties of co–zn ferrite nanocrystals for magnetocaloric applications. journal of applied physics, 107(9), 09a508. doi:10.1063/1.3338847 zhang, c. f., zhong, x. c., yu, h. y., liu, z. w., & zeng, d. c. (2009). effects of cobalt doping on the microstructure and magnetic properties of mn–zn ferrites prepared by the co-precipitation method. physica b: condensed matter, 404(16), 2327-2331. doi:https://doi.org/10.1016/j.physb.2008.12.044 https://doi.org/10.1016/j.jmmm.2004.09.138 https://doi.org/10.1016/j.ica.2015.01.014 https://doi.org/10.1016/j.jmmm.2012.10.004 https://doi.org/10.1016/j.ceramint.2016.01.177 https://doi.org/10.1016/j.physb.2008.12.044 https://doi.org/10.52131/jmps.2020.0101.0003 19 journal of materials and physical sciences volume 1, number 1, 2020, pages 19 25 journal homepage: https://journals.internationalrasd.org/index.php/jmps structural and thermal behavior evaluation of ag-pva nanocomposites synthesized via chemical reduction technique gulfam nasar1*, hazrat amin2, fawad ahmad3, shahbaz nazir4 1 department of chemistry, balochistan university of information technology, engineering and management sciences, quetta 87300, pakistan 2 govt. superior science college, higher education department, khyber pakhtunkhwa, peshawar 25200, pakistan 3 department of chemistry, university of wah, quaid avenue, wah cantt 47040 pakistan 4 punjab higher education department, govt. graduate college ravi road shahdara lahore pakistan article info abstract article history: received: april 11, 2020 revised: june 07, 2020 accepted: june 28, 2020 available online: june 30, 2020 silver nanoparticles were prepared via process of chemical reduction using sodium borohydride as reductant. the prepared nanoparticles were then utilized for synthesizing various compositions of nanocomposites with polymeric matrix of poly (vinyl alcohol). for doing so, the nanoparticles were dispersed in the polymer solution by vigorous stirring. the solutions of the nanocomposites were cast in films. the nanocomposite films were used for various characterization techniques; out of which three are being reported in this communication; xrd, tga/dta and sem. the upshot of xrd proposes a semi-crystalline nature of synthesized nanocomposite. the crystalline character of the nanocomposite enhances with an increasing doping concentration of the prepared nanoparticles. thermal analysis suggests the degradation pattern of the polymer nanocomposite material and represents that thermal stability improves as the silver nanoparticles are added. the sem micrograph reveals a uniform surface with a well dispersed nanoparticle in the polymer matrix. keywords: poly (vinyl alcohol) silver nanoparticles nanocomposites scanning electron microscopy (sem) thermogravimetric analysis (tga/dta) x-ray diffraction (xrd) © 2020 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: gulfam.nasar@buitms.edu.pk 1. introduction nanocomposite materials have gathered attention of the research community over the past few years. the nanocomposites offer a variety of applications in various fields of technology (ismail, salleh, & ahmad, 2011) and daily life e.g. charge storing devices, conducting materials, (liu, xue, zhang, & zhai, 2014) magnetic (azhar khan et al., 2015) devices, biology(uppugalla, male, & srinivasan, 2014), superconductors (lebaron, wang, & pinnavaia, 1999) and super capacitors (burke, 2000) etc. the emergence of interest towards the conducting polymers and their interactions with inorganic nanoparticles has opened new horizons of research and technology to make a variety of conducting nanocomposites. these materials can be used to obtain maximum performance in their target devices(radja, djelad, morallon, & benyoucef, 2015). out of many reported methods of preparation of nanocomposites using the filler material and polymer matrix, three of the main methods comprise solution-intercalation, melt-compounding and in-situ polymerization. in this regard photopolymerization has been used extensively in order to prepare nanocomposites from the monomers and the filler material (decker, keller, zahouily, & benfarhi, 2005). in order to prepare a nanocomposite material it is very pertinent that the components of the nanocomposite should be compatibilized (larraza, peinado, abrusci, catalina, & corrales, 2011) so as to get the https://journals.internationalrasd.org/index.php/jmps mailto:gulfam.nasar@buitms.edu.pk gulfam nasar, hazrat amin, fawad ahmad, shahbaz nazir 20 maximum of the synergic effect of both the components of the resulting material (nasar, khan, & khalil, 2010). the properties of the nanocomposite actually depict the degree of compatibility of matrix and the filler material involved in the manufacture of nanocomposite. xrd has been one of the most prominent tools employed for investigating assembly structure of composite material. in the current study we have tried to find a relation between the concentration of nanoparticles with the structure and thermal properties of the nanocomposite. 2. experimental procedure 2.1. chemicals used in this study, the following substances were employed. silver nitrate, poly (vinyl alcohol) (pva approximately 125,000 g / mol), poly vinyl (pyrrolidone), sodium borohydride, de-ionized water as solvent. 2.2. synthesis of pva/ag polymer nanocomposites before using, the pva and other ingredients were vacuum dried. de-ionized water was used to make a stock solution of pva (5 percent w/w). in 100-gram milipore grade water, 0.45 gram of sodium borohydride was added and dissolved. in the same way, silver nitrate solution was prepared by dissolving 0.75-gram silver nitrate in 250 gram de-ionized water. an ice bath was used to chill a freshly made sodium borohydride solution. with constant vigorous stirring, solution of silver nitrate was added to solution of borohydride slowly by dripping via burrete. when a rich yellow tint appeared, the procedure was halted. poly (vinyl pyrollodone) solution (2 percent) was added to the reaction mixture at this point in order to stabilize the freshly prepared nanoparticles. in an airtight flask, the solution was kept. five fractions containing various percentages of silver nanoparticles were introduced to different beakers containing five solutions of pva from the mother solution. for 12 hours, each solution was magnetically stirred. 2.3. casting in petri dishes (diameter = 14 cm), five different solutions of different concentrations of prepared nanocomposites were put. for film formation, a series of petri dishes arranged on a flat platform at ambient temperature. the solvent evaporation technique produced smooth and homogeneous films. dried and finished films were carefully removed from petri dishes and were sized into suitable designs and dimensions for various characterization procedures. 2.4. characterization to characterize the produced polymer composites, the following characterization procedures were used. 2.4.1.xrd analysis the produced nanocomposite samples were characterized for x-ray diffraction using the "rigaku (japan) fx gieger series rad-b system." for this, a one-square-inch sample size was used. the cut sample was then fixed into a sample holding assembly with a 35 kv acceleration voltage. scanning angles ranged from 10 to 50 degrees, with a current of 20 ma used for x-ray diffraction. 2.4.2.thermal analysis the thermal behaviour of the produced nanocomposite material was evaluated using “diamond tg/dta machine manufactured by perkin elmer instruments, usa”. the machine's sample chamber was filled with 5-8 mg. the heating rate was kept uniformly at 5oc/ min using an automated furnace. for a few minutes, the temperature was kept 30°c while being exposed to air pressure and gases before releasing nitrogen gas to the sample journal of materials and physical sciences 1(1), 2020 21 room in a constant state. all other variables were kept constant while heating was initiated. from 30°c to 600°c, the heating was maintained at a constant rate. the mass loss was calculated as a function of temperature using various samples, thus tg/dta graphs were attained. 2.4.3.scanning electron microscopy morphological studies were carried out for silver-pva nanocomposite samples using a "jeol microscope sem sj-6490lvma made in germany." the result of the same study made a sense of how nanoparticles contained in the polymer matrix were distributed. the nanocomposite images were collected at voltages ranging from 5 kilo volt to 20 kilo volt. image resolutions ranging from 500 x to 100,000 x were employed. 3. results and discussion 3.1. x-ray analysis of pva /ag composite results of xrd pattern of the prepared nanocomposites are shown in figure 1. mass of the nanoparticles in the said samples ranged from 1 mg to 5 mg, containing a middle value of 3 mg. the sample's crystalline behaviour is depicted in the figure. the outcome is consistent with previous research (park et al., 2006). the nanocomposite samples exhibit a larger region from 2θ=5o to 11o, followed by a peak at 19.3o, 29.3o, followed by relatively lesser intensity peaks at 26.3o, 35.89o, 39.1o, 42.87o, 47.3o, and 48.3o. the findings support the hypothesis that adding silver nanoparticles improves the crystalline character of resultant material as compared to pure polymer. the peak intensity at 2θ =19.3o attributable to pva tends to diminish as a function of greater amount of ag nanoparticles, resulting in higher intensity of neighboring peaks. similar findings have been reported in previous investigations (kaczmarek & podgórski, 2007). figure 1: xrd results of ag-pva nanocomposites of a: 1mg ag np, b: 3mg ag np and c: 5mg ag np as evidenced by the other strong peak, a peak with lesser intensity suggests greater amorphous character. overall, as evidenced by the peaks in the picture, the introduction of silver nanoparticles improves crystalline character of prepared nanocomposite material. gulfam nasar, hazrat amin, fawad ahmad, shahbaz nazir 22 3.2. thermal analysis of pva /ag composite differential thermal gravimetric analysis and thermo gravimetric testing were performed on selected samples of the produced nanocomposites. the outcomes are shown in figure 2. the nanocomposite lost weight in three stages, according to the researchers. for three different samples, thermal degradation occurred at 417k, 428k, and 430k respectively. the first step entails each sample losing 12.5 percent, 14 percent, and 13 percent of its weight, respectively. evaporated water is responsible for this portion of the weight loss, resulting in a completely dried sample. chemical degradation occurs at 473k. for all three samples, this procedure resulted in a decrease in mass at the rate of 56.5, 55, and 52 % respectively. the next phase is combustion, which occurs after the introduction of oxygen gas in the sample chamber at 573 degrees fahrenheit. after this phase, increasing the temperature shows no discernible effect. figure 3 reveals thermal investigations showing that thermal stability is a function of doping of filler in the prepared material. figure 2: tga of ag-pva nanocomposites of a: 1mg ag np, b: 3mg ag np and c: 5mg ag np figure 3: dta of ag-pva nanocomposites of a: 1mg ag np, b: 3mg ag np and c: 5mg ag np 0 100 200 300 400 500 600 0 20 40 60 80 100 % w ei g h t temperature( 0 c) a b c 0 100 200 300 400 500 600 m ic ro vo lt s temperature o c a b c journal of materials and physical sciences 1(1), 2020 23 3.3. scanning electron microscopy the results of morphological study of the surface structure of silver nanoparticlesare shown in figure 4. this micrograph was magnified by a factor of 100,000. the size of the particles is indicated by markers, as seen in figure 4. the size of silver nanoparticles spans from 15nm to 40nm, as can be shown. similarly the results of the morphological study of the nanocomposite material is shown in figure 5. the sample thickness was between 100 and 200 m. the micrograph shows a smooth morphology of the sample film attributed to the greater degree of compatibility of the filler and the matrix, which results in a homogenous structure of the prepared material having evenly distributed filler particles in the polymer matrix bulk as well as on surface with a perfect morphology. evenly discrete ag nanoparticles imbedded in pva matrix are readily visible as black dots. figure 4: sem image of the silver nanoparticles figure 5: sem image of ag-pva nanocomposite gulfam nasar, hazrat amin, fawad ahmad, shahbaz nazir 24 4. conclusion the chemical reduction approach was used to successfully produce silver nanoparticles. using the physical dispersion approach, these nanoparticles were successfully integrated into the poly (vinyl alcohol), resulting in a polymer-silver nanocomposite. the nanocomposite material was developed into uniform and smooth films, which were then characterized structurally and thermally. the xrd results indicate that the generated samples have a semi-crystalline structure, with the crystalline character of the material increasing as 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(2014). design and synthesis of heteroatoms doped carbon/polyaniline hybrid material for high performance electrode in supercapacitor application. electrochimica acta, 146(0), 242-248. doi:http://dx.doi.org/10.1016/j.electacta.2014.09.047 http://dx.doi.org/10.1016/j.electacta.2014.09.047 https://doi.org/10.52131/jmps.2020.0102.0006 48 journal of materials and physical sciences volume 1, number 2, 2020, pages 48 57 journal homepage: https://journals.internationalrasd.org/index.php/jmps synthesis and characterization of rare earth (ce) substituted magnesium ferrite mgce0.1fe1.9o4 and banana peel bpmgce0.1fe1.9o4 atiq ur rehman1, mukhtar ahmad2* 1 department of physics, riphah international university, lahore 2 department of physics, comsats university islamabad, lahore campus, lahore article info abstract article history: received: august 13, 2020 revised: october 28, 2020 accepted: november 18, 2020 available online: december 31, 2020 in this study, a composite of cerium doped magnesium ferrite (mgcexfe2-xo4, x= 0.1) and banana peel powder was prepared by hydrothermal method. crystal structure and phase identification, chemical bonding, and magnetic properties were characterized by x-ray diffraction (xrd), fourier transform infrared (ftir) and vibrating sample magnetometry (vsm), respectively. xrd results reveal that the prepared ferrite exhibits single phase face centered cubic (fcc) structure having no impurity in the sample. addition of banana peel powder has no effect on the crystal structure. the values of structural parameters greatly match with the earlier reported values for the same structure. ftir results clearly indicate that the prepared ferrite is spinel and have well defined vibrational and stretching peaks due to different molecules present in the compound. coercivity values for both ferrite and composite materials are found to be a few hundred oersted which confirm the soft magnetic nature of this ferrite. the observed parameters show that the prepared composite may find technological application for microwave absorption and multi-layer chip inductors. keywords: hydrothermal method fourier transform infrared spinel ferrites fcc structure soft ferrites © 2020 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: ahmadmr25@yahoo.com 1. introduction nano sized spinel ferrites possess interesting electrical and magnetic features for various technological applications including high frequency devices, supercapacitors, photocatalytic and wastewater treatment (greenwood & earnshaw, 2012). the hydrothermal method will be used to prepare rare earth ce-substituted (mgcexfe2-xo4 , x= 0.1) monoferrite with enhanced magnetization and higher active functional sites for easy magnetic separation. substitution of ce may affect dc resistivity, ac conductivity and magnetic properties and the substituted material can be used at higher working frequencies where low eddy current losses are desirable. in addition, ce ions can be used to improve the remanence magnetization and decrease the dielectric loss, respectively but these ions cause reduction in the saturation magnetization, coercivity and permeability of the material and thus cannot be used for microwave devices. ferrites substituted with rare earth (ce) may alter the number of active sites through magnetic, electrical and physical properties can be enhanced (datta, deb, & tyagi, 1996; gaumat, rastogi, & misra, 1992; pickering, 1985). the doping with rare earth at both mg and fe site is good choice. the dissimilar ionic radius of (ce) compared to fe will introduce structural distortions, thus modifying the fe-o, mg-o bond lengths and fe-o-fe bond angles. (high cost) this modification will lead to the optimum magnetic and dielectric properties of the material. moreover, the charge compensation due to different valance states of fe compared to ce will create vacancies of oxygen and the fluctuation of the iron valency due to different valence states which will effectively improve the electrical properties. thus, increased electrical resistivity causes to https://journals.internationalrasd.org/index.php/jmps mailto:ahmadmr25@yahoo.com atiq ur rehman, mukhtar ahmad 49 reduce eddy currents which are beneficial for a material working at higher frequencies. hence, it is worth studying the structural, elastic and magnetic properties of rare earthsubstituted mgce0.1fe1.9o4 and banana peel bpmgce0.1fe1.9o4. different methods are used to difluoride water such as electrolysis, reverse permeation, ion exchange, chemical precipitation and adsorption (goraya, 2021). the method of removing fluoride depends on factors such as capital and operational cost. operating cost, environmental impact and fluorine removal efficiency method. for example, distillation has the ability to remove ions from water, but it is very expensive. this electro dialysis method uses ion exchange membranes and electric potential removal of different types of ions from aqueous solutions (rehman, yusoff, & alias, 2015). it has a cation and anion exchange membranes between cathode and anode. the cations migrate when they fall negative ions increase. these ions penetrate the membrane and are retained through oppositely charged electrodes (wang et al., 2013). the limitation of this method has low efficiency of trace removal concentrations of pollutants in aquatic media (chen et al., 2016). ion exchange process can also be used in which ions removed from an aqueous solution and are replaced by another type of ion. ion exchange confirms the passage of water by exchanging polymer ions, it is a water-insoluble substance that can exchange some of its ions with similarly charged ions in an aqueous media. many natural organic materials contain ions exchange properties or it can be added to them by chemical modification. this function has been used to produce ionic spare parts from natural materials. use nitric acid as an oxidant to modify wood, fiber, peat and carbon concentrated sulfuric acid is used to introduce sulfonic acid groups. muhammad abdur rehman. et al. (2015) prepared a series of doped and un-doped magnetic ferrites cucexfe2-xo4 (x=0.0--0.5) doped ferrite proved superior with respect to functional growth sites and adsorption of fluoride. fluoride adsorption capacity was adversely affected by the presence of associated anions such as hco3-1, so4-2, no3-1, cl-1and as. these anions compete for ferrite active sites during adsorption (rehman et al., 2015). jing wang at el. (2013) prepared ce-zro2 nanocages for fluoride removal from water and investigated their performance. the prepared adsorbent showed good adsorption capacity in 3-7 ph range. the optimal ph range was 3.4--4.5. at ph 4.0 the capacity was found to be as high as 175mg/g. simultaneous presence of chloride and arsenate in high concentration reduced fluoride adsorption. presence of sulphate had no effect but hco3reduced efficiency. electrostatic interaction and anion exchange were reported to pay key role in fluoride removal mechanism (wang et al., 2013). magnetic ferrite (mgfe2o4) is efficient for various applications of ferrites. doping with cerium (ce) enhances adsorption capacity of mgcexfe2-xo4 by increasing active functional sites and dispersion of particles. addition of banana peels powder further improves the adsorption ability of mgcexfe2-xo4. therefore, we have a plan to investigate the mgcexfe2xo4/banana peels composite ions different applications. 2. synthesis techniques 2.1. synthesis of magnetic ferrite by hydrothermal method 33.3ml aqueous solution of metal chlorides with concentration 1mol/l was prepared for each mgcl2, cecl3.8h2o and fecl3.6h2o. it was achieved by dissolving 3.7g of mgcl2, 1.3g of cecl3.8h2o and 17.12g of fecl3.6h2o in 33.3ml deionized water in separate beakers. each beaker, except for that containing fecl3.6h2o was covered with aluminum lid. each container was placed on hot magnetic plat (at 60 oc) for 30 minutes while stirring the solution during this interval. then the contents of all three containers were mixed. the sample so obtained was stirred for 2 hours on hot magnetic plate at 60 ℃. then the contents were left to cool to room temperature and then were transferred in teflon lined stainless steel autoclave. the autoclave with its contents was placed in a gradually heated oven (at 180 ℃) for 6 hours. then the oven was put off to cool the contents to room temperature. the sample was washed thrice by deionized water to eliminate chlorides. after that the contents were placed in a gradually heated dry oven at (60 ℃) for 24 hours. the final product was our required ferrite in powder form. journal of materials and physical sciences 1(2), 2020 50 flow chart below depicts the procedure for synthesizing magnesium ferrite is shown in figure 1. figure 1: flow chart of preparation procedure of magnesium ferrite 2.2. preparation of banana peel dust banana peels were collected and washed thoroughly, first with tap water and then with deionized water. then these peels were placed in a dry oven at 60oc for 12 hours. after that the peels were broken into small pieces and again were left for 24 hours in the oven at 60oc. finally, the dried peels were crushed in kitchen grinder. following flow chart summarizes the procedure for preparing banana peel powder. figure 2: flow chart of banana peel powder preparation procedure 3. results and discussion 3.1. x-ray diffraction (xrd) analysis xrd technique was applied to synthesized magnesium ferrite. sample material was heated at 180 ℃ for 12 hours. match software was used for phase identification and analyzing average crystalline size, crystal structure and lattice parameters. the index patterns (figure 3) matched with jcpds card number 00-017-0464 (icdd -01-073-1720). atiq ur rehman, mukhtar ahmad 51 this indicates that crystals are face centered cubic in structure having space group fd3m and space group number is 227. average crystalline size was determined using scherer’s equation. d=k λ/β cosθ (1) d being crystallite size, λ is wavelength of radiations emitted by copper source, β the full width at half maximum and θ the angle of diffraction. the value was found to be 15.76 nm for (mgcexfe2-xo4) ferrite. 10 20 30 40 50 60 70 80 in te n s it y ( a .u ) 2-theta (degree) mgfe 2 o 4 figure 3: xrd graph for magnesium ferrite table 1 lattice parameters for magnesium ferrite hkl 2 (degrees)  (degrees) a (å) 220 33 16.5 6.1 311 36 18 8.2 400 42 21 8.597 422 49 24.5 9.09 511 54 27 8.81 440 62 31 8.41 442 68 34 8.26 533 75 37.5 2.52 average value of a = 7.498 (å), volume (a3) = 421.5379 å3, x-ray density (dx = 8m/nav) = 6.3 g/cm3 journal of materials and physical sciences 1(2), 2020 52 10 20 30 40 50 60 70 80 in te n s it y ( a .u ) 2-theta (degree) banana powder figure 4: graph of xrd result for banana peel powder banana peel is amorphous material. it contains minerals, nutrients and fabrics. concentration of minerals is as under table 2. 10 20 30 40 50 60 70 80 in te n s it y ( a .u ) 2-theta (degree) (mgfe 2 o 4 + banana peels) figure 5: graph of xrd result for composite material atiq ur rehman, mukhtar ahmad 53 table 2 the concertation table of minerals minerals concentration (mg/g) k 78.10 mn 76.20 na 29.30 ca 19.20 fe 0.61 table 3 lattice parameters for composite material hkl 2 (degrees)  (degrees) a (å) 200 20 10 8.2 221 24 12 10.4 331 33 16.5 11.8 522 36 18 6.89 400 38 19 9.46 422 48 24 9.27 611 54 27 10.4 440 64 32 8.22 620 72 36 8.28 534 75 37.5 8.9 cell volume = 580.09 (å3), x-ray density = 2.8g/cm3, crystalline size =17.8nm 3.2. fourier transform infrared spectroscopy (ftir) graph of ftir for the prepared composite shows absorption band at around 535cm-1. these bands are the results of stretching vibrations of fe3+–o2 on tetrahedral and octahedral sites suggesting magnesium ferrites to be inverse spinel. symmetric vibration of no3 group caused band at 1384cm-1. bands at 3410 and 2922 cm-1 can be attributed to stretching o–h vibrations. absorption band at 1625 cm-1 is caused by the bending of water molecules. bands at 3573cm-1 and 632 cm-1 are distinguishing features of o–h stretching vibrations. at 3423 and 1639 cm-1stretching and bending of adsorbed molecules of water can be noted. the band occurring at 3446 cm−1 and those existing at 1638cm-1 and 1121 cm−1 are due to the symmetric stretching vibrations of o–h groups and hydrogen-bonded surface molecules respectively. this suggests the presence of absorbed or free water in the sample. from these vibrations it is concluded that the sample still retains hydroxyl groups. band at 1380 cm−1 is the characteristics of symmetric vibration of no3− group. sharp band at 997 cm−1 is the indication of mg-based ferrite. vibrations of metal oxide are generally below 1000cm1. so, the peaks at 997 and 710 cm−1 show the presence of fe-o bonding. existence of band around 475 cm−1 confirms the spinal structure of prepared material. on the spectrum obtained for pure magnesium ferrite, broad peeks occur at 592cm-1 and 631 cm-1. these peaks occur due to fe–o bond stretching vibrations which indicate that tetrahedral sites are occupied by feþ3 ions. splitting of n1 band at 570 cm-1, is associated with fe–o bond of fe3o4. a weak peak is formed at 434 cm-1which appears due to the presence of feþ3 –o2 bond at octahedral sites. existence of these peaks indicate spinel structure of fe3o4. existence of broad peak at 3446cm-1 and sharp peak at 1635 cm-1 is caused by stretching and bending of vibrations of hydroxyl group. occurrence of these peaks is clear indication of adsorption of water at the surface of fe3o4. peaks formed at 1242 cm-1, 1193 cm-1 and 1149 cm-1 occurred due to symmetrical stretching vibrations and ester bond. a broad band at 3442 cm-1 is attributed to hydroxyl stretching vibrations. peak at 590 cm-1 shows presence of ferric oxide particles. the peaks at 3446 cm-1 and 1635 cm-1 are the evidence of the existence of adsorbed water. 550 cm-1 band is the identification of cubic crystalline forms of cerium which shows that cerium ions occupy octahedral sites. interplanar distance increases when feþ2 ions are replaced by ceþ4 ions. the peak at 726 cm-1 is generated by the vibrations of ce–o ions. the spinel structure of the filler material is confirmed by these results. journal of materials and physical sciences 1(2), 2020 54 figure 6: ftir graph for composite material figure 7: ftir graph for banana powder atiq ur rehman, mukhtar ahmad 55 figure 8: ftir graph for magnesium ferrite 3.3. vibrating sample magnetometer (vsm) magnetic measurements were carried out by vibrating sample magnetometer. the magnetic properties of synthesized pure magnesium ferrite and its composite with banana peel powder were determined at room temperature for applied field range from -8000 to +8000 oe as shown in figure 9. the stoner-wolfforth model was used to calculate the magnetic saturation, the relation is as under: m (h) = ms (1-ha2sin𝜽/ 8h2) (2) where ms = magnetic saturation, ha = anisotropy field, 𝜽 = angle b/w m and h. the ms value obtained from m-h loop for pure ferrite was 47emu/g and for composite with banana peel powder was 42emu/g. the magnetic moment (nb) was calculated by using the formula: nb (µb)= m x ms/5585 (3) here m is the molecular weight of the sample and ms is the saturation magnetization. magnetic moment of magnesium ferrite is found to be 1.78 and that for composite material is 1.550. the remnant magnetization (mr) is the magnetization left behind after removing applied field. the value of remnant magnetization was determined from hysteresis loop. mr value for magnesium ferrite was 8 emu/g and for its composite with banana peel powder is 7.2 emu/g. coercivity is the strength of the field in reverse direction which reduces sample magnetization to zero. the coercivity of pure magnesium ferrite is 155 oe and that of composite material is 150 oe. the squareness, that is, the ratio mr and ms is an importantant application of ferromagnetic material. this value for magnesium ferrite and its composite with banana peel powder is 0.16 and 0.19 respectively. magnetic anisotropy k was calculated using the relation: journal of materials and physical sciences 1(2), 2020 56 hc = 0.96 x k / ms (4) table 4 magnetic properties of mgfe2o4 and mgfe2o4 + banana peel powder property mgfe2o4 mgfe2o4+ banana peel powder ms(emu/g) 48 emu/g 42 emu/g mr(emu/g) 8emu/g 7.2emu/g mr/ms 0.16 0.20 ub(nb) 1.718 1.50 k (magnetic anisotropy) 7750 6562.5 hc (oe) 155oe 150oe figure 9: magnetization variation at room temperature with applied magnetic field for mgfe2o4 and its composite with banana peel powder value of k for mgfe2o4 and prepared sample of the composite is found to be 7750 and 6562.5, respectively. thin hysteresis loop indicates low coercivity and retentivity of the sample and suggests that the material is soft ferrite. banana peel is non-magnetic in nature; hence its addition to magnesium ferrite reduced ms values of the composite. coercivity (hc) of the magnesium ferrite is slightly higher than that for the composite. it is because of the large particle size of magnesium ferrite due to addition of peels. in order to obtain better soft behavior banana peel powder is added which results in lowering magnetic saturation and coercivity. the hysteresis loop for the composite material is thinner as compared to that for pure magnesium ferrite. the obtained magnetic parameters may be suitable for adsorption of fluoride from water body. 4. conclusion in this work, cerium doped magnesium ferrite and its composite of with banana peel were successfully synthesized using hydrothermal method. xrd results revealed the crystal structure of magnesium ferrite to be face centered cubic having volume 587.43å3 and x-ray density 6.3g/cm3. the crystal structure for the composite remains unaltered because of the amorphous nature of banana peels powder. crystallite size for mgfe2o4 was determined as 15.76 nm. ftir clearly shows that sample material is spinel ferrite having well defined stretching and bending vibration modes. values of ms,nb, mr, hc, mr/ms and k for pure atiq ur rehman, mukhtar ahmad 57 mgfe2o4 are 48emu/g, 1.718, 8emu/g, 155oe, 0.16 and 7750, respectively. these values for the fabricated composite material in the same order are 42emu/g, 1.50, 8emu/g, 150oe, 0.19 and 6562.5, respectively. these results and the shape of hysteresis loops clearly indicate that prepared material is soft ferrite. ftir clearly shows that sample material is spinel ferrite having well defined stretching and bending vibration modes. the observed parameters of the materials suggest that they may find applications in different fields such as transformer cores, multilayer chip inductors (mlcis) and most importantly in treating the fluoride contaminated water body. references chen, l., zhang, k.-s., he, j.-y., xu, w.-h., huang, x.-j., & liu, j.-h. (2016). enhanced fluoride removal from water by sulfate-doped hydroxyapatite hierarchical hollow microspheres. chemical engineering journal, 285, 616-624. doi:https://doi.org/10.1016/j.cej.2015.10.036 datta, p. s., deb, d. l., & tyagi, s. k. (1996). stable isotope (18o) investigations on the processes controlling fluoride contamination of groundwater. journal of contaminant hydrology, 24(1), 85-96. doi:https://doi.org/10.1016/0169-7722(96)00004-6 gaumat, m., rastogi, r., & misra, m. (1992). fluoride level in shallow groundwater in central part of uttar pradesh. bhu-jal news, 7(2), 17-19. goraya, n. r. (2021). synthesis of magnesium ferrite (mgcexfe2-xo4)/banana peel composite for de-fluoridation of real water body. greenwood, n. n., & earnshaw, a. (2012). chemistry of the elements: elsevier. pickering, w. (1985). the mobility of soluble fluoride in soils. environmental pollution series b, chemical and physical, 9(4), 281-308. doi:10.1016/0143-148x(85)90004-7 rehman, m. a., yusoff, i., & alias, y. (2015). fluoride adsorption by doped and un-doped magnetic ferrites cucexfe2-xo4: preparation, characterization, optimization and modeling for effectual remediation technologies. journal of hazardous materials, 299, 316-324. doi:https://doi.org/10.1016/j.jhazmat.2015.06.030 wang, j., xu, w., chen, l., jia, y., wang, l., huang, x.-j., & liu, j. (2013). excellent fluoride removal performance by ceo2–zro2 nanocages in water environment. chemical engineering journal, 231, 198-205. doi:https://doi.org/10.1016/j.cej.2013.07.022 https://doi.org/10.1016/j.cej.2015.10.036 https://doi.org/10.1016/0169-7722(96)00004-6 https://doi.org/10.1016/j.jhazmat.2015.06.030 https://doi.org/10.1016/j.cej.2013.07.022 https://doi.org/10.52131/jmps.2022.0301.0023 22 journal of materials and physical sciences volume 3, number 1, 2022, pages 22 28 journal homepage: https://journals.internationalrasd.org/index.php/jmps theoretical investigation of ferromagnetism and optical properties of cucr2x4 (x = s, se) spinels via ab-initio calculations q. mahmood1*, jameelah alzahrani1, t. ghrib1 1 department of physics, college of science, imam abdulrahman bin faisal university, p.o. box 1982, 31441, city dammam, saudi arabia article info abstract article history: received: march 03, 2022 revised: april 28, 2022 accepted: june 29, 2022 available online: june 30, 2022 the spintronics technology improve the spin functionality which captivated the existence of ferromagnetism. the control of magnetic properties by electrons spin and transport effect have been illustrated in cucr2x4 (x = s, se) spinels dft through wien2k and boltztrap codes. the negative formation of energy established the thermodynamic stability of the examined spinels. the half metallic ferromagnetism in the analyzed spinel’s assures density of states. magnetic moment (integer value) and the insulating nature with down spin is the reaction of 100% spin polarization. the δ(𝑑)>(δ𝐶𝐹) and negative δ(𝑝𝑑) attainment of the condition have presented the prevailing part of electrons spin to create ferromagnetism. keywords: density functional theory electronic characteristics magnetic properties crystal field energy © 2022 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: qmmustafa@iau.edu.sa 1. introduction the half metallic ferromagnetism has been a theme of intense attention due to inherent technologically usage in significant spintronic, ferroelectric, and ferromagnetic applications displaying in spinels (lunkenheimer, fichtl, hemberger, tsurkan, & loidl, 2005; mahmood et al., 2020; c. sun et al., 2010). researchers have fascinated in view of the attention of cmr (colossal maneto-resistance) between studied spinels due to transition metal ferro-spinels among these spinels (baltzer, wojtowicz, robbins, & lopatin, 1966; von helmolt, wecker, holzapfel, schultz, & samwer, 1993). cdcr2s4 and cdcr2se4 are technically the two vital transition of temperatures at 84.5k and 129.5k separately in ferromagnetic semiconductors (hemberger et al., 2005). in these type of materials s ions (in cdcr2s4) or six se ions (in cdcr2se4) forms the surrounding and crystallize in cubic spinel structure. in ferro-magnets, electrostriction has been discovered for it (lunkenheimer et al., 2005; c. p. sun et al., 2010). by using electric field cmr may be stimulated in these spinels as it has been reported besides it (c. sun et al., 2010). magnetic properties of such materials has extended the significance by application view point in the study of field induced electrical characteristics (kim, myung, yoon, kang, & sun, 2004). cucr2s4 has been investigated by wustrow et al investigated to exploit cucr2s couple at high voltage which belongs to cu thiospinels family (wustrow et al., 2018). in this presumed research work cucr2s4 comprises of the synthesis, structural and electrochemical examinations.cucr2s4 testified studies displays that stable compound with normal distribution of cations indicates that compound is stable (zhang, stevanović, d’avezac, lany, & zunger, 2012). pyrochlore lattice created at tetrahedral positions by the combination of cr ions in which antiferromagnetic interaction among closest neighbors that restricts the spin alignment as well as magnetic prevention (anderson, 1956). though, the soc effect reduces the ferromagnetism by producing balance states and least free energy, but this energy simultaneously helps the magnetic ordering. the least energy creates net magnetic ordering in it. particularly magnetic frustrations due to cr bonded by tetragonal contraction which surprised by creating it valuable contender in spintronics and other electronic devices by zncr2o4 and cdcr2o4 (dutton, huang, tchernyshyov, broholm, & https://journals.internationalrasd.org/index.php/jmps mailto:qmmustafa@iau.edu.sa q. mahmood, jameelah alzahrani, t. ghrib 23 cava, 2011; kumar, fennie, & rabe, 2012; tran & blaha, 2009). the mgcr2o4 and zncr2o4 studied ensure their sensitivity to ferromagnetism. instead of limiting literature the ferromagnetic ordering and high magnetic moment had been explored in cucr2x4 (x = s, se). furthermore, the insulting band gaps 0.938 ev and 0.638 ev for cucr2s4 and cucr2se4 also reported which make them significant materials for transport applications (madsen & singh, 2006). the literature analysis about these materials show the experimental research work is very limiting on cucr2se4 but few theoretical reports exist on cucr2x4 (x=s, se) which support to analyze them for spintronic applications. therefore, in the view of above discussion, the theoretical studies of transport and magnetic behaviors of cucr2x4 (x=s, se) have been incorporated in this article. for this task, the dft based wien2k code, and boltztrap code has been practiced exploring the structures of studied spinels (perdew et al., 2008). these exact band gap structures are run for the transport analysis by boltztrap code (tran, blaha, & schwarz, 2007). the existence of structures of spinels reveals their diverse applications in the field of spintronic. therefore, the results are discussed step by step below for the complete of the studied spinels. 2. method of calculation the thiospinels cucr2x4 (x=s, se) magnetism and transport characteristics have been done by fp-l(apw+lo) method through the wien2k code. the structural analysis and ground state study has been done by pbe-gga (koller, tran, & blaha, 2011). the optimizations of studied structures done until the all the strain forces becomes zero. in addition, for true electronic structures and band gap analysis, the tb-mbj has been done through exchange and correlation configuration. the tb-mbj improve the band gaps this high precision and less time (blaha, schwarz, madsen, kvasnicka, & luitz, 2001; rashid et al., 2019; scheidemantel, ambrosch-draxl, thonhauser, badding, & sofo, 2003). by using tb-mbj exchange potential results achieved from thermoelectric as well as electronic band structures conveyed. the k-mesh of order 12 × 12 × 12 have been selected in first brillion zone. furthermore, the product rmt×kmax= 8, gmax = 16 and lmax are adjusted in the in put of the software. 3. analysis section 3.1. electronic characteristics the spinel's cucr2x4 (x=s, se) with cubic structure and and space group fd3m#227 are optimized to in ferromagnetic state and compared its energy released with nonmagnetic state. the energy is taken the default units (ry) in both the fm and nm states. the relative investigation depicts that the more energy released in fm state than nm states, which approve the fm state is much stable than the nm states. the thermodynamic stability of the deliberate spinel's, and also associated with the enthalpy formation which has been computed and reported in the table 1.the thermodynamic stability guarantees the negative establishment of energy that declines from -1.46 ev to 0.34 ev as s is changed with se. the stability, decreasing trend as we go down the group the exit of energy lessens by the substitution of s with se. when structures optimized the lattice constantsa0 (å) by murnaghan equation of states and shown in table 1. bulk modulus decreases by increasing the s/se size and distance among atoms whereas the lattice constant increase from cucr2s4 to cucr2se4. the computed magnetic and electronic and electronic characteristics are illustrated to see the effect of electrons spin. thorough explanation of band structures (bs) is essential to recognize the electronic behavior. hence, the examined compounds are plotted in fig.2. for the computation of band structures. at γsymmetry point direction the valence band maxima exist, and conduction band minima exists at χ direction having ef on vb in up spin (↑) which depict the indirect band gap. journal of materials and physical sciences 3(1), 2022 24 figure 1: optimized energy versus volume plots of (a) cucr2s4, and (b) cucr2se4 in fm and nm states figure 2: the band structures for spin up and spin down of (a, b) cucr2s4 and (c, d) cucr2se4 while in down spin (↓) medium, both vbm and cbm exist at the γ direction having fermi level inside them which persuades the insulting gap because of exchange mode. hence, the formation of ferromagnetic semiconductors results as the incorporation of up spin (↑) and down spin (↓) medium by insulting properties. q. mahmood, jameelah alzahrani, t. ghrib 25 table 1 the calculated lattice constant a0 (å), bulk modulus b0 (gpa), ground state energy difference (δe = enm-efm), enthalpy of formation ∆h(ev) for cucr2x4 (x = s, se, te). aref (tran & blaha, 2009), ref (mahmood, hassan, et al., 2019)b the density of states (dos) shows identical functioning and shown in figs.3 the 𝑆𝑃 = 𝑁↓−𝑁↑ 𝑁↓+𝑁↑ 𝑋100 is the equation computed for spin polarization in which n↑ showing the total density of states in the up-spin mode while n↓ is the total density of states in the down spin mode? densities of states exist at fermi level in up spin (↑) mode however energy gaps are forbidden inside the fermi level. consequently, sp has been found hundred percent (choi, shim, & min, 2006; walsh et al., 2007). the sp can be maintained by the integer value of total mm of the studied compounds is 100% as presented in table 2. partial density of states (pdos) cu, cr and s/se demonstrates further the exchange mechanism and ferromagnetism and are examined thoroughly as shown in fig.3. the hybridize in the energy interval -4.0 to -0.5 ev between 3d states of cr/cu and o-2p states exist near ef in up spinel mode. whereas in down spin mode the range is from -3.0 to -1.0 ev for cr-3d states, cu-3d and s-3p states. moreover, in the hybridization range for cr-3d states, cu-3d states and s-3p states in the conduction band in the range of 1.5 to 2.4 ev and 2 to 3.2 ev for spin up and down modes. consequently, ferromagnetic semiconducting nature, generated by the interaction inside the valence band and separating of states in the down spin mode. figure 3: the total and partial dos for spin up and spin down of (a, b) cucr2s4 and (c, d) cucr2se4 compound a0 (å) b0(gpa) ∆e (ev) ∆h(ev) cucr2s4 10.22 82.74 5.74 -1.46 exp. 10.24a, 10.1b cucr2se4 10.76 65.35 6.74 -0.84 exp. ---- journal of materials and physical sciences 3(1), 2022 26 table 2 the total and the local magnetic moments (in bohr magneton) calculated for mgcr2x4 (x = s, se, te) total (µb) int. ( µb) mg (µb) cr (µb) (xµb) cucr2s4 3.0000 0.43 0.006 3.02 -0.06 cucr2se4 3.0000 0.54 0.002 3.05 -0.09 3.2. magnetic properties the materials structures elaborated in this material generates crystal field and exchange energies by hybridization in distinct states. tetrahedral arrangement of s/se atoms effect the cu site with valency +2, whereas cr site having +3 valency is captured by the octahedron of s/se atoms. the repulsive effect of 3d-cr creates the octahedral of s/se which in the near octahedron is powerful and weaker as move away. the increasing energy eg of states as associated to t2g states that extend the octahedron medium of s/se atoms separate the 3dcr into high energy (eg) and low energy (t2g) (kumar et al., 2012; mahmood, rashid, et al., 2019) [30]. energies of the crystal field energies in both spin modes described by )( 2  −= ggcf et and )( 2  −= ggcf et are shown in table 3.furthermore the correlation of crystal energy with the exchange separating of 3d states of cr determined by the relation ))(  −= dd d ferromagnetism domination results in the larger value of exchange energy besides the crystal field energy. by the measurement of indirect exchange energy )( pd another kind of energy is produced by 3d states of cr and p states of s/se. lower energy support ferromagnetism when )( pd is negative. cucr2s4 to cucr2se4 the value of )( pd and )(d increases presented in table 3 where cf decreases that clearly indicates that later one is more promising for ferromagnetism. ferromagnetism can be elaborated by exchange constant that calculated by the relations = sxen c  0 and , 0 = sxen v  where )(  −= vvv eee and )(  −= ccc eee and the energies at valence band as well as on conduction bands, where x is the absorption of cr and s is mm of cr atom. in usual cases the 0 ( )n  retain positive values and )( 0 n negative. therefore, the similar effect of studied fm has been seen in table 3. table 3 the calculated values spin down gap (eg (ev)), crystal field energy (δecrystal), direct exchange δx(d) and indirect exchange δx(pd) and the exchange constants (noα and noβ) for cucr2x4 (x = s, se, te). compounds eg (δecrystal) δx(d) δx(pd) noα noβ cucr2s4 1.45 3.70 3.98 -0.20 0.33 -0.14 cucr2se4 0.85 2.94 4.10 -0.25 0.52 -0.16 zenger’s exchange model supports the attraction of down spin mode whose energy reduces and shows the magnetic impurity operated have negative value )( 0 n (hassan, arshad, & mahmood, 2017; kant, deisenhofer, tsurkan, & loidl, 2010; mahmood, yaseen, haq, laref, & nazir, 2019). therefore, the source of ferromagnetism confirm that this is due to exchange energies. the examined compounds of magnetic moments and partial mm are reported in table 2. the transporting of magnetic moment towards nonmagnetic sites indicates that the exchange interaction cr-3d states and s/se p states causes the decrease of magnetic moment of cr. because of unlike exchanges included in the structures may be due to transition of mm from magnetic to nonmagnetic sites. 4. conclusion in short, the present article, ensure the detailed analysis of electronic and magnetic characteristics of cucr2x4 (x=s, se) by wien2k code. the examined compounds are ferromagnetic semiconductors, that validates the electronic band structures and density of q. mahmood, jameelah alzahrani, t. ghrib 27 states. the optimization analysis confirms the more energy release in fm states than in nm states ensures the stability of fm states. the fm is elaborated in terms of electrons spin which show strong hybridization. the fm is favorable because δ(𝑑) has higher values as compared to (δ𝐶𝐹). the energy decreases in down spin mode have -ve value of pdexchange energy which is also the justification of fm and electrons spin. the p-d hybridization/exchange interaction is due to the growth of μcr and shifting of mm on nonmagnetic sits. therefore, the complete analysis of magnetic characteristics ensures importance of studied materials for spintronic applications. references anderson, p. w. 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(2012). prediction of a 2 b x 4 metal-chalcogenide compounds via first-principles thermodynamics. physical review b, 86(1), 014109. https://doi.org/10.52131/jmps.2021.0201.0012 12 journal of materials and physical sciences volume 2, number 1, 2021, pages 12 21 journal homepage: https://journals.internationalrasd.org/index.php/jmps investigation of structural, spectral, and dielectric properties of cdsubstituted nicopr nano ferrites alina manzoor1*, muhammad abubakar1, amir muhammad afzal2, muhammad imran arshad1, m. nasir rasul3 1 department of physics, government college university, faisalabad,38000, pakistan 2 department of physics, riphah international university, 13-km raiwind road, lahore-54000 pakistan 3 institute of physics, the islamia university of bahawalpur, bahawalpur-63100, pakistan article info abstract article history: received: february 24, 2021 revised: april 29, 2021 accepted: june 28, 2021 available online: june 30, 2021 the effect of cadmium ions on the structural, spectral, and dielectric properties of pr doped ni0.4co0.6-xcdxfe1.95pr0.05o4 ferrites synthesized by the self-ignited sol-gel process is investigated in the present work. the addition of cadmium ions in place of cobalt ions resulted in an increase in the lattice constant. x-ray diffraction experiment revealed the singlephase spinel structure. the obtained average crystallite size is ranging from 20 30 nm. by increasing the substitution of cadmium ions, the dielectric constant, dielectric loss (tan δ) and impedance are noted to increase. sem study found the spherical grain morphology with some degree of agglomeration. the existence of pores, the sintering process, and the magnetic activity of the particles may be responsible for nanosized particles with a homogeneous particle size distribution. raman spectra revealed a slight shifting in raman modes with cadmium addition which may be attributed to the strain produced due to the presence of larger cadmium ions at the fe3+ site. keywords: xrd raman spectra dielectric impedance sol-gel process © 2021 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: alinamanzoor@gmail.com 1. introduction in the field of nanotechnology, devices and systems are designed, characterized, and implemented by regulating the shape and size of the materials. these controlled-sized materials are immensely used for industrial and domestic applications such as imaging, mechanical industries, telecommunication, catalysis, medical and environmental applications. thus, nanotechnology advances the fundamental principles of nano-scale materials and their applications (devan, kolekar, & chougule, 2006). with the decrease of particle size, the surface area of nano-sized materials increases which steer the quantumsize effect (zhang et al., 2020). due to the growing surface area, that is the principal navigating force to reduce sintering-temperature of the particles, and this reduces the free energy during sintering (akhtar, nazir, tahir, qamar, & khan, 2020). the specific chemical and physical properties of nanoparticles make them highly appropriate for the design of new and improved materials and devices. spinel ferrites are commonly used to monitor the propagation direction, frequency, amplitude, and phase of microwave signals in microwave devices. to maximize the construction of these devices and to aid in the production of ferrite, a precision measurement of dielectric and magnetic properties at working frequencies and temperature ranges is needed to work out (lassoued & li, 2020). in view of applications, the ferrites have become more fascinating because of their high resistivity values (102 1010 ohm-cm) that are nearly 15 times higher in magnitude than iron (varma, bharadwaj, & babu, 2019). https://journals.internationalrasd.org/index.php/jmps mailto:alinamanzoor@gmail.com alina manzoor, muhammad abubakar, amir muhammad afzal, muhammad imran arshad, m. nasir rasul 13 their applicability at high frequency, good resistance to heat, and greater corrosion resistance are other reasons that make them most significant. ferrites are excellent soft magnetic materials for high-frequency applications due to low cost, high resistivity, and low eddy current losses that have been thoroughly tested for the application of multi-layer chip inductors (mlci) (junaid et al., 2020). the incorporation of rare earth (re) ions in the lattice of spine ferrites leads to the re-fe linkage (4f-3d coupling), the reason behind the changes in the curie temperature and magnetization of ferrites (elayakumar et al., 2019). moreover, the substitution of transition elements into a spinel structure drastically affects the structural, optical, magnetic, and dielectric properties (pan, sun, han, zhang, & zhao, 2019). there are different methods to fabricate the nanocrystalline ferrites like sol-gel auto combustion or controlled combustion method, co-precipitation method, solid state reaction, and hydro-thermal methods etc. (akhtar, babar, qamar, ur rehman, & khan, 2019; el nahrawy, soliman, sakr, & el attar, 2018; huq, saha, ahmed, & mahmood, 2013; jalilvand & faghihi-sani, 2013). among these, sol-gel is the most suitable method due using inexpensive precursors, good morphology, easy of handling, controlled size of particles, controlled composition, and homogeneity along with other advantages such as costeffective method, highly reactive powder, low external energy consumption, and no need of special equipment. 2. experimental single phase cd-substituted ni0.4co0.6xcdxfe1.95pr0.05o4 (x=0-0.6) nano-ferrites were synthesized via sol-gel self-ignition technique. the balanced stoichiometric amounts of all salts were taken. citric acid with 1:1 m ratio was added into the nitrate solution as an oxidizing agent. the solution was stirred for 15-20 minutes to achieve a homogeneous solution and after that small amount of ammonia solution was added to attain ph 7 of the solution. the solution was constantly stirred with heating on at 250 oc. the solution was converted into thick gel within 1 hour and after some time the auto combustion took place, and fluffy dark grey ferrite ash was collected. after fine grinding of grey ferrite powder, sintering was carried out at 900 oc. the final fine-grinded sintered samples were characterized through different techniques and their various properties were investigated in detail. xrd experiment was done to analyze the structural properties of material including crystalline size, lattice constant, cell volume, and x-ray density etc. the dielectric properties were analyzed through lcr technique. in order to explore the material’s morphology, chemical composition, and crystalline structure, scanning electron spectroscopy (sem) was used. for the imaging of samples, secondary electrons and back-scattered main electrons are used. intraand inter-molecular vibrational information is provided by raman spectroscopy which also provided the additional understanding of reactions that are useful for material identification. 3. results and discussion 3.1. xrd analysis the x-ray diffraction patterns of all samples of cd-substituted ni0.4co0.6 xcdxfe1.95pr0.05o4 (x=0-0.6) are shown in figure 1. all necessary diffraction peaks can be seen from these xrd patterns that correspond to different planes; specified as (220), (311), (400), and (511). it is determined from these miller indices that the fabricated materials have a face centered cubic structure belonging to space group fd3m (valenzuela, 2012). the most intense diffraction peak (311) is found at 35.6 ̊ which considered as the characteristics peak of the spinel matrix. the recorded patterns are well matched with an icdd card reference number 00-010-0325. it is observed that the lattice constant is changed enormously by changing the composition of the samples in figure 2. the value of lattice constant first increases for x=0.15 and after that it decreases for x up to 0.6. this decreasing effect is attributed to the smaller ionic radii of cadmium ions than that of the cobalt ions. the decrease in the lattice constant is primarily due to the contraction of the spinel lattice since the lattice starts to journal of materials and physical sciences 2(1), 2021 14 contract when smaller size cd ions tried to replace the larger sized co ions (modak, ammar, mazaleyrat, das, & chakrabarti, 2009). 20 25 30 35 40 45 50 55 60 x = 0.60 x = 0.45 x = 0.30 x = 0.15 in te n s it y ( a .u ) 2 theta (degree) ni 0.4 co 0.6-x cd x fe 1.95 pr 0.05 o 4 x = 0.0 (220) (311) (400) (511) figure 1: combine xrd patterns of ni0.4co0.6-xcdxfe1.95pr0.05o4 ferrites 0.0 0.1 0.2 0.3 0.4 0.5 0.6 8.15 8.20 8.25 8.30 8.35 8.40 8.45 8.50 l a tt ic e c o n s ta n t concentration lattice constant å figure 2: graph between concentration and lattice constant the crystallite size (d) from each peak is calculated and then an average value of d is taken for each sample. the average value of crystallite size is ranging from 20-30 nm. a nonlinear variation in d is observed as a function of cd concentration. figure 3 represents the variation of crystallite size as a function of cd concentration. it is observed that from the concentration x = 0 to x = 0.15 the crystallite size is drastically reduced and after that it increases. alina manzoor, muhammad abubakar, amir muhammad afzal, muhammad imran arshad, m. nasir rasul 15 0.0 0.1 0.2 0.3 0.4 0.5 0.6 20 22 24 26 28 30 32 c ry s ta l s iz e ( n m ) concentration crystal size figure 3: graph between concentration and average crystallite size the x-ray density is calculated using the following relation. ρx= 8m/na3 (1) here, m is the molecular weight of the composition, n is the avogadro number, and a is the lattice constant. the value of x-ray density is ranging from 5.41 to 6.16 g/cm3. it is observed that with increasing cd substitution, the x-ray density is also increased. this increase in the xray density is due to the fact that the x-ray density is directly dependent on the molecular weight as well as on the lattice parameter (gupta & coble, 1968). as we have noticed that the lattice constant is decreased with the concentration while the atomic mass of cd (112.4 amu) is greater than that of co (58.93 amu). so, it is expected to increase the x-ray density. figure 4: graph between concentration and x-ray density journal of materials and physical sciences 2(1), 2021 16 3.2. sem study scanning electron micrographic (sem) images of representative ferrites samples doped with cd and rear earth praseodymium showed the surface morphology (figures 5a5e). samples are sintered at 900 oc and clusters of fine agglomerated spherical particles of uneven size are found almost homogeneously and uniformly distributed. the agglomeration is observed to reduce by increasing the cd substitution. the replacement of co by cd leads to enhance the crystallinity of the materials. the agglomeration indicates the porous nature, particles of nanometer sizes, and a homogenous particle size distribution that can be responsible for the magnetic behavior of the particles. analysis of the sem images for cobalt ferrites doped with cd and pr showed that the samples are composed of smaller grains. these results are in line with the calculated scherrer crystallite dimension, as discussed above, using the xrd data for cadmium doped cobalt ferrites. figure 5a: sem image of ni0.4co0.6fe1.95pr0.05o4 ferrite figure 5b: sem image of ni0.4co0.45cd0.15fe1.95pr0.05o4 ferrite alina manzoor, muhammad abubakar, amir muhammad afzal, muhammad imran arshad, m. nasir rasul 17 figure 5c: sem image of ni0.4co0.30cd0.30fe1.95pr0.05o4 ferrite figure 5d: sem image of ni0.4co0.15cd0.45fe1.95pr0.05o4 ferrite figure 5e: sem image of ni0.4cd0.60fe1.95pr0.05o4 ferrite journal of materials and physical sciences 2(1), 2021 18 3.3. raman spectroscopy the raman spectra of nicofe2pro4 nano particles substituted by cd2+ are shown in the figure 6. the cd2+ ions have greater ionic radius to occupy the tetrahedral (a) site due to which the structural disorder of the sublattice of oxygen has increased. all 6 raman active modes assigned as 2a1g (596 613 cm-1, 672 688 cm-1), eg (292 305 cm-1), 3t2g (538 574 cm-1, 454 467 cm-1, 200 250 cm-1) can be seen in the spectra. a 1g active mode, usually referred to as the shoulder a1g (2), is a function of spinal ferrite reverse and combined. the vibration models of over 600 cm-1 conduct to stretch symmetrically the metal oxygen bond of the tetrahedral sites and to bend oxygen at octahedral positions in modes under 600 cm-1; both symmetrically and unsymmetrically. a slight shifting activity is found in raman modes with cadmium substitution that can be attributed to the strain caused by the inclusion of the broader cadmium ions at the fe3+ site. the tetrahedral site is symmetrically bent with fe ion in relation to an oxygen atom by the fe-o mode (haque, huq, & hakim, 2008; rahman & ahmed, 2005). 0 200 400 600 800 1000 1200 1400 1600 1800 in te n s it y raman shift (cm -1 ) x = 0.60 x = 0.45 x = 0.30 x = 0.15 x = 0 a1g a1g eg t2g t2g t2g figure 6: raman scattering of ni0.4co0.6-xcdxfe1.95pr0.05o4 ferrites 3.4. dielectric study the room-temperature dielectric measurements are taken for a frequency range of 1 khz to 107 hz. the figure 7 has shown the variation in dielectric constant (έ) as a function of frequency (f) of the ac field applied. it shows the conductive behavior of un-doped and cd doped cobalt ferrites. at lower frequencies, the value of dielectric constant is observed to be high which further decreases with increasing the frequency of applied field. this is a typical behavior of ferrites, already investigated and reported by various researchers (akhtar et al., 2020; caltun, spinu, & stancu, 2001). the contribution to conduction phenomenon in ferrites comes from four major processes; polarization contributions at lower frequencies, i.e., dipolar and space charge, electrical, ionic, and some of the polarization contributions at higher frequencies, allowing the dielectric constant (έ) to decrease. the space-charge polarization model holds two parts: the grains (more conductive layer) and grain boundaries (less conductive and more resistive). the accumulation of space charge carriers in a dielectric medium is preferred to move through a resistive part (grain boundaries) of the sample. so, a finite time is required by the charge carriers to position their axes in the direction of alternating electric field. thus, by increasing the frequency, the charge carrier remained incapable to sustain with the field reversals and consequently dielectric constant starts to decrease (nam, jung, shin, & oh, 1995; pardavi-horvath, 2000). alina manzoor, muhammad abubakar, amir muhammad afzal, muhammad imran arshad, m. nasir rasul 19 1000 10000 100000 1000000 1e7 0 5 10 15 20 25 x=0.00 x=0.15 x=0.30 x=0.45 x=0.60 d ie le c tr ic c o n s ta n t frequency (hz) figure 7: graph between frequency and dielectric constant the overall value of dielectric constant is observed to decrease with an increase in cd concentration. in addition, in nanosized ferrites, the number of grain boundaries are larger which causes high dielectric constant at lower frequencies, whereas low-dielectric grains at high frequencies have more contribution (byun, byeon, hong, & kim, 1999). the variation of loss tangent loss as a function of applied field frequency for all samples is represented in figure 8. it can be seen that the loss tangent is increases as the concentration of cd ions increases while it increases with increasing the applied field frequency. 1000 10000 100000 1000000 1e7 0 5 10 15 20 25 x=0.0 x=0.15 x=0.30 x=0.45 x=0.60 l o s s t a n g e n t frequency (hz)  figure 8: graph between frequency and loss tangent journal of materials and physical sciences 2(1), 2021 20 the variation in impedance as a function of applied field frequency for all samples is represented in figure 9. the value of the impedance decreases as the applied field frequency increases, and it becomes almost constant at a point and seems to be independent of the frequency. by increasing the concentration of cd ions, the value of impedance is also increased. for x > 0.45, there is a sudden increase in the impedance value. 1000 10000 100000 1000000 1e7 -1x10 7 0 1x10 7 2x10 7 3x10 7 4x10 7 5x10 7 6x10 7 7x10 7 8x10 7 9x10 7 1x10 8 1x10 8 im p e d e n c e ( o h m ) frequency (hz) x=0.00 x=0.15 x=0.30 x=0.45 x=0.60 figure 9: graph between frequency and impedance 4. conclusion cd-substituted ni0.4co0.6-xcdxfe1.95pr0.05o4 (x=0-0.6) nano-ferrites synthesized via sol-gel method are investigated for various properties. xrd results confirmed the development of fcc spinel structure with crystallite sizes ranging from 20 to 30 nm. the incorporation of cd at co positions leads to an increase in lattice constant from 8.194 å to 8.457 å and a decrease in x-ray density. dielectric constant observed to decrease while impedance of materials noted to increase with increase in cd substitution. sem analysis confirmed the spherical morphology of the constituted grains with some degree of agglomeration. a slight shifting in raman modes has observed due to the presence of greater ionic radius of cd at the fe3+ sites. due to the fe-o mode, the perfectly straight bending of the oxygen ions with respect to the fe ions at the tetrahedral site is detected. references akhtar, m. n., babar, m., qamar, s., ur rehman, z., & khan, m. a. (2019). structural rietveld refinement and magnetic features of prosademium (pr) doped cu nanocrystalline spinel ferrites. ceramics international, 45(8), 10187-10195. doi:10.1016/j.ceramint.2019.02.069 akhtar, m. n., nazir, m. s., tahir, z., qamar, s., & khan, m. a. (2020). impact of co doping on physical, structural, microstructural and magnetic features of mgzn nanoferrites for high frequency applications. ceramics international, 46(2), 17501759. doi:10.1016/j.ceramint.2019.09.149 byun, t. y., byeon, s. c., hong, k. s., & kim, c. k. (1999). factors affecting initial permeability of co-substituted ni-zn-cu ferrites. ieee transactions on magnetics, 35(5), 3445-3447. doi:10.1109/20.800552 caltun, o. f., spinu, l., & stancu, a. (2001). magnetic properties of high frequency ni-zn ferrites doped with cuo. ieee transactions on magnetics, 37(4), 2353-2355. doi:10.1109/20.951170 alina manzoor, muhammad abubakar, amir muhammad afzal, muhammad imran arshad, m. nasir rasul 21 devan, r., kolekar, y., & chougule, b. (2006). effect of cobalt substitution on the properties of nickel–copper ferrite. journal of physics: condensed matter, 18(43), 9809. el nahrawy, a., soliman, a., sakr, e., & el attar, h. (2018). sodium-cobalt ferrite nanostructure study: sol-gel synthesis, characterization, and magnetic properties. journal of ovonic research, 14(3). elayakumar, k., manikandan, a., dinesh, a., thanrasu, k., raja, k. k., kumar, r. t., . . . baykal, a. (2019). enhanced magnetic property and antibacterial biomedical activity of ce3+ doped cufe2o4 spinel nanoparticles synthesized by sol-gel method. journal of magnetism and magnetic materials, 478, 140-147. doi:10.1016/j.jmmm.2019.01.108 gupta, t., & coble, r. (1968). sintering of zno: i, densification and grain growth. journal of the american ceramic society, 51(9), 521-525. doi:10.1111/j.11512916.1968.tb15679.x haque, m. m., huq, m., & hakim, m. (2008). influence of cuo and sintering temperature on the microstructure and magnetic properties of mg–cu–zn ferrites. journal of magnetism and magnetic materials, 320(21), 2792-2799. doi:10.1016/j.jmmm.2008.06.017 huq, m., saha, d., ahmed, r., & mahmood, z. (2013). ni-cu-zn ferrite research: a brief review. journal of scientific research, 5(2), 215-234. doi:10.3329/jsr.v5i2.12434 jalilvand, g., & faghihi-sani, m.-a. (2013). fe doped ni–co spinel protective coating on ferritic stainless steel for sofc interconnect application. international journal of hydrogen energy, 38(27), 12007-12014. doi:10.1016/j.ijhydene.2013.06.105 junaid, m., khan, m. a., abubshait, s. a., akhtar, m. n., kattan, n. a., laref, a., & javed, h. m. a. (2020). structural, spectral, dielectric and magnetic properties of indium substituted copper spinel ferrites synthesized via sol gel technique. ceramics international, 46(17), 27410-27418. doi:10.1016/j.ceramint.2020.07.227 lassoued, a., & li, j. (2020). magnetic and photocatalytic properties of ni–co ferrites. solid state sciences, 104, 106199. doi:10.1016/j.solidstatesciences.2020.106199 modak, s., ammar, m., mazaleyrat, f., das, s., & chakrabarti, p. (2009). xrd, hrtem and magnetic properties of mixed spinel nanocrystalline ni–zn–cu-ferrite. journal of alloys and compounds, 473(1-2), 15-19. doi:10.1016/j.jallcom.2008.06.020 nam, j., jung, h., shin, j., & oh, j. (1995). the effect of cu substitution on the electrical and magnetic properties of nizn ferrites. ieee transactions on magnetics, 31(6), 3985-3987. doi:10.1109/20.489838 pan, x., sun, a., han, y., zhang, w., & zhao, x. (2019). structural and magnetic properties of bi 3+ ion doped ni–cu–co nano ferrites prepared by sol–gel auto combustion method. journal of materials science: materials in electronics, 30(5), 4644-4657. doi:10.1007/s10854-019-00757-8 pardavi-horvath, m. (2000). microwave applications of soft ferrites. journal of magnetism and magnetic materials, 215, 171-183. doi:10.1016/s0304-8853(00)00106-2 rahman, i., & ahmed, t. (2005). a study on cu substituted chemically processed ni–zn–cu ferrites. journal of magnetism and magnetic materials, 290, 1576-1579. doi:10.1016/j.jmmm.2004.11.250 valenzuela, r. (2012). novel applications of ferrites. physics research international, 2012. varma, m. c., bharadwaj, s., & babu, k. v. (2019). observation of anomalous site occupancy in ni-co-cu-cr ferrite system synthesized by sol-gel method. physica b: condensed matter, 556, 175-182. doi:10.1016/j.physb.2018.12.002 zhang, w., sun, a., zhao, x., pan, x., han, y., suo, n., . . . zuo, z. (2020). structural and magnetic properties of ni–cu–co ferrites prepared from sol-gel auto combustion method with different complexing agents. journal of alloys and compounds, 816, 152501. doi:10.1016/j.jallcom.2019.152501 https://doi.org/10.52131/jmps.2022.0301.0025 38 journal of materials and physical sciences volume 3, number 1, 2022, pages 38 47 journal homepage: https://journals.internationalrasd.org/index.php/jmps dosimetric comparison of intensity modulated radiation therapy (imrt) and rapid arc in cervix carcinoma farrukh huma1, khalid iqbal2, g. murtaza1*, nawaz muhammad1, ghulam farid3 1 centre for advanced studies in physics, gc university, lahore 2 department of clinical and radiation oncology, shaukat khanum memorial cancer hospital and research centre lahore 3 department of applied physics, university of barcelona, c/martí i franquès, 1, 08028 barcelona, catalunya, spain article info abstract article history: received: april 08, 2022 revised: june 18, 2022 accepted: june 29, 2022 available online: june 30, 2022 in this study, the comparison of dosimetric parameters for imrt and ra while treating the patients suffering from cervical carcinoma are analyzed. a total number of 20 patients were selected, out of which, 10 were treated with imrt and the other 10 with ra. as per radiation therapy oncology group (rtog), oars were also marked on ct images and oncologist did the contouring for planning target volume (ptv), clinical target volume (ctv), and gross target volume (gtv). the dosimetric parameters include verity of index and coverage which were calculated for the plans’ calculation and oars doses. two samples of paired t-tests have been performed to find the difference of dosimetry for ra and imrt plans. in the ra and imrt planning, 0.96 is the conformity index mean values. the results shows that the mean value for paddick conformity index was 0.93 while new conformity index value was 1.06. keywords: imrt ra cervical carcinoma rtog © 2022 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: gmrai@gcu.edu.pk 1. introduction around the globe, cervix carcinoma is the fourth most common gynaecological threat. due to this kind of carcinoma illness, developing nations are generally affected. the globocan 2013 report agreed that almost 70% of worldwide burden cascade is in developing nations. for the administration of cervix carcinoma, external radiotherapy is acknowledged as a standard of care (torre, siegel, ward, & jemal, 2016). the purpose of radiotherapy for cervix carcinoma is to attain an ideal adjust among most extreme measurements to the tumor and to reduce the chance of muddling the organs at risk (oars) (parkin, bray, ferlay, & pisani, 2001). basically, cervical cancer begins in women’s cervix, which is the lower contract portion of the uterus. the uterus holds the developing baby amid pregnancy. the cervix interfaces the lower portion of the uterus to the vagina and with the vagina shapes the birth canal. there are three types of treatment options namely; surgery, radiation therapy, and chemotherapy. radiotherapy accepts fundamental analytics for the administration of 50% of cancer patients and almost 40% of cured claim their malignancy required radiotherapy. for a portion of patients, there could a chance to utilize radiation treatment instead of surgery, pointing organ assurance (adegoke, kulasingam, & virnig, 2012; barton & delaney, 2010). to treat the cervix cancer, a customary procedure of box strategy or high energy photon (2-dimensional) with ap/pa fields have been reported (gupta et al., 2009). it has been observed that the use of customary method delivered superfluous dosages to adjacent basic organs, subsequently driving to treatment related complications which were an enormous https://journals.internationalrasd.org/index.php/jmps mailto:gmrai@gcu.edu.pk farrukh huma, khalid iqbal, g. murtaza, nawaz muhammad, ghulam farid 39 issue, especially considering the high rate of remedy versus survival of illness. the most widely utilized strategy of treatment planning is 3-dimensional conformal radiotherapy (3-d crt), where high rates of side impacts have been observed when combined with chemotherapy (peters iii et al., 2000; samper-ternent, zhang, kuo, hatch, & freeman, 2011). imrt can reduce the radiation dose to oars, and supply predominant coverage to the planning target volume (ptv) (guy et al., 2016). in 2015, guy et al. reported that in terms of quality indices, especially oars when compared with 3d-crt, the intensity modulation techniques have numerous preferences (guy et al., 2016). furthermore, the progressed frame of imrt is ra that delivers a precise dose with a gantry rotation of 360o in a single or multi-arc treatment. over a long period of time for the treatment of cancer, imrt has been replaced by ra. when compared with imrt, ra can reduce the number of monitor units which are required to provide medicine (fenkell et al., 2008). rapid arc is a volumetric arc therapy (vmat) modality that allows rapid delivery of highly conformal dose distributions. in 2010, benthuysen et al. shared that for treating capacity, ra is more promising. it was observed that for advisor moment and monitor units, ra is much proficient as compared to imrt (van benthuysen, hales, & podgorsak, 2011). similarly, in 2017, yadav et al., concluded that ra permits far better correspondence, the high dose volume to planning target volume (ptv) when compared with 3d-crt. it may offer assistance to reduce the chance of inferior cancer (yadav et al., 2017). in this study, we present a systematical comparison of dosimetric parameters for imrt and ra of the patients with cervical carcinoma. 2. materials and method 2.1. treatment planning and selection of patients through obstetrics stage ib-iva and federation of gynecology, 20 number of patients (aging between 23 to 76 years) were confirmed suffering from cervix carcinoma. after institutional review board approval, these 20 patients were selected for localized cervical cancer therapy treatment. ten patients were originally treated with imrt while the others with ra technique. in 28 fractions, the recommended dose was 50.4 gy (1.8 gy each day). the important aim was to provide 95% of the recommended dose to the 95% of the planning target volume (ptv) in any case for all the plans and then to decrease the oar (bladder, rectum, and small bowl) dosage. during optimization, the physicist and the oncologist amend precedence for better results. both plans were optimized for 6 mev photon energy. as per radiation therapy oncology group (rtog), oars were also marked on ct images and oncologist did the contouring for planning target volume (ptv), clinical target volume (ctv), and gross target volume (gtv). for all treatment plans, delivery of isodose and optimization, the eclipse radiation treatment planning system (ertps), (eclipse aria 11, varian associates, palo alto, ca) with pencil beam and helios contrary planning software has been used (iqbal, isa, buzdar, gifford, & afzal, 2013). for delivering treatment, varian dhx (varian medical system, palo alto, ca) with 120 leaf millennium mlc has been used. table 1 patient’s characteristics n = 20 patient’s age median (year) 56 range (year) 32-76 stage iia 4 iiia 2 iva 3 ib 3 iib 4 iiib 4 journal of materials and physical sciences 3(1), 2022 40 2.2. quality parameters to assess various dosimetric parameters of oars and ptv, eclipse tps created a dose volume histogram. the analyzed dosimetric parameters included the followings. i. conformity index (ci) the conformity index is defined as the ratio of ref. isodose volume to the target volume (shaw et al., 1993). 𝐶𝐼 = 𝑅𝑒𝑓.𝑖𝑠𝑜𝑑𝑜𝑠𝑒.𝑣𝑜𝑙𝑢𝑚𝑒 𝑇𝑎𝑟𝑔𝑒𝑡 𝑣𝑜𝑙𝑢𝑚𝑒 (1) (the 95% of isodose volume was taken as reference volume of the ptv according to icru reports.) ii. new conformity index (nci) 𝑁𝐶𝐼 = (𝑇𝑉×𝑃𝐼𝑉) (𝑇𝑉𝑃𝐼𝑉)2 (2) where, tvpiv = volume of piv tv = total volume of the target (nakamura et al., 2001) iii. paddick conformity index (pci) 𝑃𝐶𝐼 = (𝑇𝑉𝑃𝐼𝑉)2 𝑇𝑉×𝑃𝐼𝑉 (3) where, tv = total volume of the target (paddick, 2000) iv. homogeneity index (hi) homogeneity index is defined as the ratio of difference dose delivered to 1% of the ptv and dose delivered to 99% of the ptv to the prescribed dose (kataria, sharma, subramani, karrthick, & bisht, 2012). 𝐻𝐼 = 𝐷1%−𝐷99% 𝑃𝑒𝑟𝑠𝑐𝑟𝑖𝑝𝑡𝑖𝑜𝑛𝐷𝑜𝑠𝑒 (4) where, d1% = dose delivered to 1% of the ptv d99% = dose delivered to 99% of the ptv v. radical dose homogeneity index (rdhi) if one take the ratio of the minimum dose to the maximum dose delivered to the target volume then the results will be radical dose homogeneity index (oliver, chen, wong, van dyk, & perera, 2007). 𝑟𝐷𝐻𝐼 = 𝐷𝑚𝑖𝑛/𝐷𝑚𝑎𝑥 (5) where, dmin = minimum dose dmax = maximum dose vi. moderate dose homogeneity index (mdhi) the mdhi is the ratio between two quantities; one is dose reaching 95% of the target and other is dose reaching 5% of the target volume (oliver et al., 2007). 𝑀𝐷𝐻𝐼 = 𝐷95% 𝐷5% (6) farrukh huma, khalid iqbal, g. murtaza, nawaz muhammad, ghulam farid 41 where, d95% = dose delivered to 95% of the ptv d5% = dose delivered to the 5% of the ptv vii. uniformity index (ui) the uniformity index which is the ratio of d5% to the d95% (sheng, molloy, larner, & read, 2007). 𝑈𝐼 = 𝐷5% 𝐷95% (7) where, d5% = dose given to the 5% of the ptv d95% = dose given to 95% of the ptv viii. gradient index (gi) the gradient index is defined as the ratio of half prescription isodose volume to the prescription isodose volume (paddick & lippitz, 2006). 𝐺𝐼 = 1 2 𝑃𝐼𝑉 𝑃𝐼𝑉 (8) where, piv = prescribed isodose volume. ix. coverage coverage index is the ratio between the minimum dose delivered to the prescription dose delivered to the target volume (shaw et al., 1993). 𝐶𝑜𝑣𝑒𝑟𝑎𝑔𝑒 = 𝐷𝑚𝑖𝑛 𝑃𝑟𝑒𝑠𝑐𝑟𝑖𝑏𝑒𝑑 𝐷𝑜𝑠𝑒 (9) where, dmin = minimum dose reaching the target 3. statistical analyses in statistical analyses, two samples paired t-test has been performed to find the difference of dosimetry between ra and imrt plans for cervix carcinoma. the results were analyzed by taking the assistance of statistical package of social sciences software (spss, version 20), in which the p < 0.05 was considered to get statistically significant and accurate results. 4. results 4.1. organs at risk (oars) rectum, bladder, and small bowel were marked as oars and reported for dose. table 2 presents the calculated results of both techniques imrt and ra. the results revealed that by using the ra technique, the oars dose decreases comparing to imrt except for the dose to the small bowel. technically, it is more convenient for the radiation therapy department to reduce the time and number of monitor units, where ra technique is found more promising. journal of materials and physical sciences 3(1), 2022 42 table 2 dose comparison of imrt and ra to oars imrt rapid arc rectum bladder small bowel rectum bladder small bowel dmean 115.12 125.91 43.82 110.31 123.20 63.22 d100% 2.60 8.68 0.67 2.42 4.53 1.83 d70% 19.71 23.76 8.55 18.06 23.08 12.83 d50% 36.48 36.25 18.00 33.77 38.05 22.30 d30% 48.34 47.01 27.21 46.09 47.52 32.74 d10% 49.88 50.98 40.79 49.74 50.01 46.62 4.2. comparative analysis of imrt and ra since the ci is used to measure how well the dose distribution covers the size and shape of the target. under the calculation of both techniques, we calculated the mean value of ci up to 0.96, as presented in table 3. similarly, in 2000, paddick proposed a ci, considering the position of the prescription volume with respect to the target volume to get perfect conformity score (nakamura et al., 2001). therefore, by using the formula of paddick ci, our calculated mean value is 0.93 for both techniques. furthermore, nakamura et al., proposed a new conformity index considering the location of prescription volume (nakamura et al., 2001), and by using the formula our mean calculated values of new conformity index is 1.06 for both techniques by using the equation 2. t-test conducted for the comparative analysis of both techniques showed that the results are insignificant which means that implementation of both the techniques gave the same favorable results in terms of conformity as shown in table 3 the homogeneity index (hi) is an objective tool to examine the uniformity of dose delivery in the target volume which is an important quality indicator for plans. for homogeneity of dose, two indices are used. the first one is the radical dose homogeneity index (rdhi) which is defined as the minimum dose divided by maximum dose with calculated mean values of 0.68 and 0.66 for imrt and ra techniques respectively. the second is a moderate dose homogeneity index (mdhi), which is less affected by steep dose gradients near field borders or to small hot spots (oliver et al., 2007). the calculated mean values are given in table 3 for both techniques and their comparison has also been presented in fig.1 (i-ix). the statistical analyses showed that the results are significant which means that there is a slight difference between imrt and rapid arc planning treatment. figure 1 (a-c): shows the comparative analyses of ci, pci, nci of imrt and ra (c) (b) (a ) farrukh huma, khalid iqbal, g. murtaza, nawaz muhammad, ghulam farid 43 to assess the uniformity of all the plans, a ui was used. the mean calculated values are 1.11 and 1.09 for imrt and ra techniques respectively statistical analysis shows that a significant result that means the value of ui of ra is slightly better than that of imrt. whereas, for both techniques, gi has 1.03 mean value. statistically, the results are insignificant which shows that there is no difference between imrt and ra treatment planning. for imrt the coverage, which is defined as, the dmin divided by the prescribed dose has a value of 0.81 and for ra is 0.83 as mean value. statistically, the results are insignificant. figure 2 (d-f): shows the comparative analyses of hi, mdhi, rdhi of imrt and ra. table 3 comparative analysis of imrt and rapid arc imrt (mean±s.d) rapid arc (mean±s.d) ci 0.96±0.022 0.96±0.018 new ci 1.06±0.025 1.06±0.020 paddick ci 0.93±0.022 0.93±0.018 hi 0.15±0.019 0.14±0.018 rdhi 0.68±0.059 0.66±0.058 mdhi 0.90±0.012 0.91±0.009 ui 1.11±0.015 1.09±0.010 gi 1.03±0.024 1.03±0.020 coverage 0.81±0.058 0.83±0.057 (d) (e) (f) journal of materials and physical sciences 3(1), 2022 44 5. discussion this study performs a dosimetric comparison of imrt and ra techniques. the ra was not superior to imrt in sparing of oars or the coverage of ptv. when compared with imrt, the ra procedure can reduce the number of monitor units which are required for treatment. in early radiotherapy treatments to examine the dose delivered to the tumor and oars, the dose volume histogram (dvh) tools are commonly used. but the disadvantages of dvh methodology are; a) it does not offer 3-d information, b) it also does not show, where inside the structure, the dose must be delivered, c) as the time passes and treatment progresses, dvh loses its precision if there is variation e.g. the tumor shrinks, the patients lose weight etc. to evaluate the quality of the treatment plan there is a need for parameters and tools. in the current study, the quality of treatment plan and oars sparing can be evaluated by comparing hi, ci, ui, gi and coverage. figure 3 (g): shows the comparative analyses of ui of imrt and ra it is normally accepted that conformity of a radio surgical plan is important for effective treatment as it represents the measure of how well the distribution of radiation follows the radio surgical target. radiation therapy oncology group (rtog) criteria define that for a perfectly conformal plan the value will be unity. if the index value is between 0.9 and 1, this would mean that the target volume is partially irradiated (considered to be a minor violation) (shaw et al., 1993). it can be noticed that there is a minor deviation from the protocol for the value of conformity index of both techniques. but nevertheless, be acceptable. farrukh huma, khalid iqbal, g. murtaza, nawaz muhammad, ghulam farid 45 figure 4 (h): shows the gi comparison of imrt and ra the ci described by shaw et al., has a fundamental flaw, as the ratio does not consider the location of piv relative to tv and plan would receive a perfect score whether piv outlines the exact periphery of tv or missed tv altogether (paddick, 2000). paddick and nakamura introduced new formulae for ci considering the position of the prescription volume with respect to the target volume. new ci values of both techniques are resulted to be in protocol defined by rtog. whereas, pci values resulted in acceptable minor deviations from the defined protocol for imrt and ra techniques. homogeneity is a tool to examine the uniformity of dose delivered to the target volume. for the homogeneous plan, the value of the homogeneity index will be close to zero (kataria et al., 2012). the ptv has a more homogeneous dose if the value of the homogeneity index is smaller. for the homogeneity of dose, two indices are used. first one is rdhi and the second is mdhi and the values are shown in table.3. figure 5 (i): shows the coverage comparison of imrt and ra journal of materials and physical sciences 3(1), 2022 46 ui was chosen due to the proximity of the target volume and oar’s which frequently lie alongside so that there are no hotspots that could expand in the adjacent regions. the lesser the values the better the uniformity of the dose (sheng et al., 2007). the value of ui of ra is slightly better than that of imrt. the gi is an influential tool that can be used to objectively measure the dose falling off the target. a promising gi reflects a steeper dose gradient and consequently, a lower applied radiation to the healthy tissues and organs. a gi ˂ 3 normally reflects a reasonably selected prescription isodose (paddick & lippitz, 2006). the values given in table 3 give reasonable results. according to rtog radiosurgery guidelines, the ideal value for coverage index is 0.9 and if coverage is less than 0.9 then it is considered as a minor deviation while a value less than 0.8 means a major acceptable deviation (shaw et al., 1993). the value of coverage in table 3 shows that there is a minor deviation but considerable to be acceptable. 6. conclusions an intensity modulated radiation therapy helps; dose intensification, improve target coverage, and reduction in the radiation dose to oars. whereas, rapid arc (ra) radiotherapy delivers a precise dose with a rotation of 360o in a single or multi-arc treatment of gantry for the patients with cervical carcinoma. the vital distinction between imrt and ra is the capability to adjust the beam control. the plans of ra are much dependent on the optimization method, and the dosimetrist has less choice to alter the dose division before arc has been considered. for monitor units and radio therapist time, the ra is much beneficial than the imrt. references adegoke, o., kulasingam, s., & virnig, b. (2012). cervical cancer trends in the united states: a 35-year population-based analysis. journal of women's health, 21(10), 1031-1037. barton, m., & delaney, g. (2010). the optimal provision of cancer treatment services. cancer control, 169. fenkell, l., kaminsky, i., breen, s., huang, s., van prooijen, m., & ringash, j. (2008). dosimetric comparison of imrt vs. 3d conformal radiotherapy in the treatment of cancer of the cervical esophagus. radiotherapy and oncology, 89(3), 287-291. gupta, d., shukla, p., bisht, s. s., aggarwal, a., dhawan, a., pant, m. c., . . . gupta, s. (2009). comparitive study of efficacy, tolerability of four field box technique vs. two field anterior posterior technique in locally advanced carcinoma cervix: a prospective analysis. cancer biology & therapy, 8(9), 759-764. guy, j.-b., falk, a. t., auberdiac, p., cartier, l., vallard, a., ollier, e., . . . magné, n. (2016). dosimetric study of volumetric arc modulation with rapidarc and intensitymodulated radiotherapy in patients with cervical cancer and comparison with 3dimensional conformal technique for definitive radiotherapy in patients with cervical cancer. medical dosimetry, 41(1), 9-14. iqbal, k., isa, m., buzdar, s. a., gifford, k. a., & afzal, m. (2013). treatment planning evaluation of sliding window and multiple static segments technique in intensity modulated radiotherapy. reports of practical oncology & radiotherapy, 18(2), 101106. kataria, t., sharma, k., subramani, v., karrthick, k., & bisht, s. s. (2012). homogeneity index: an objective tool for assessment of conformal radiation treatments. journal of medical physics/association of medical physicists of india, 37(4), 207. nakamura, j. l., verhey, l. j., smith, v., petti, p. l., lamborn, k. r., larson, d. a., . . . sneed, p. k. (2001). dose conformity of gamma knife radiosurgery and risk factors for complications. international journal of radiation oncology* biology* physics, 51(5), 1313-1319. oliver, m., chen, j., wong, e., van dyk, j., & perera, f. (2007). a treatment planning study comparing whole breast radiation therapy against conformal, imrt and tomotherapy farrukh huma, khalid iqbal, g. murtaza, nawaz muhammad, ghulam farid 47 for accelerated partial breast irradiation. radiotherapy and oncology, 82(3), 317323. paddick, i. (2000). a simple scoring ratio to index the conformity of radiosurgical treatment plans. journal of neurosurgery, 93(supplement_3), 219-222. paddick, i., & lippitz, b. (2006). a simple dose gradient measurement tool to complement the conformity index. journal of neurosurgery, 105(supplement), 194-201. parkin, d. m., bray, f., ferlay, j., & pisani, p. (2001). estimating the world cancer burden: globocan 2000. international journal of cancer, 94(2), 153-156. peters iii, w. a., liu, p., barrett, r. j., stock, r. j., monk, b. j., berek, j. s., . . . alberts, d. s. (2000). concurrent chemotherapy and pelvic radiation therapy compared with pelvic radiation therapy alone as adjuvant therapy after radical surgery in high-risk early-stage cancer of the cervix. obstetrical & gynecological survey, 55(8), 491492. samper-ternent, r., zhang, d., kuo, y.-f., hatch, s., & freeman, j. (2011). late gi and bladder toxicities after radiation for uterine cancer. gynecologic oncology, 120(2), 198-204. shaw, e., kline, r., gillin, m., souhami, l., hirschfeld, a., dinapoli, r., & martin, l. (1993). radiation therapy oncology group: radiosurgery quality assurance guidelines. international journal of radiation oncology* biology* physics, 27(5), 1231-1239. sheng, k., molloy, j. a., larner, j. m., & read, p. w. (2007). a dosimetric comparison of non-coplanar imrt versus helical tomotherapy for nasal cavity and paranasal sinus cancer. radiotherapy and oncology, 82(2), 174-178. torre, l. a., siegel, r. l., ward, e. m., & jemal, a. (2016). global cancer incidence and mortality rates and trends—an updateglobal cancer rates and trends—an update. cancer epidemiology, biomarkers & prevention, 25(1), 16-27. van benthuysen, l., hales, l., & podgorsak, m. b. (2011). volumetric modulated arc therapy vs. imrt for the treatment of distal esophageal cancer. medical dosimetry, 36(4), 404-409. yadav, g., bhushan, m., dewan, a., saxena, u., kumar, l., chauhan, d., . . . suhail, m. (2017). dosimetric influence of photon beam energy and number of arcs on volumetric modulated arc therapy in carcinoma cervix: a planning study. reports of practical oncology and radiotherapy, 22(1), 1-9. https://doi.org/10.52131/jmps.2022.0302.0028 71 journal of materials and physical sciences volume 3, number 2, 2022, pages 71 80 journal homepage: https://journals.internationalrasd.org/index.php/jmps removal of fluoride ions (f-1) from contaminated drinking water using mnfe2o4 /banana peels composite synthesized through chemical co-precipitation method muhammad sajid1, muhammad aamir1, muhammad jamil1, mukhtar ahmad2, shahzada qamar hussain3* 1 institute of chemical sciences, bahauddin zakariya university multan, pakistan 2 department of physics, comsats university islamabad (cui) lahore campus, lahore 54000 pakistan 3 institute of frontier materials, deakin university waurn ponds campus geelong, australia article info abstract article history: received: september 20, 2022 revised: october 18, 2022 accepted: december 29, 2022 available online: december 31, 2022 fluoride (f) contaminated water is of immense health risk. skeletal as well as dental fluorosis is due to the excessive fluoride (> 1.5 mg/l) concentration in drinking water. in the present work, mnfe2o4 /banana peels composite a unique adsorbent has been explored for the elimination of fluoride from aqueous system. these nanocomposites were characterized by xrd and ftir. retentivity and coercivity value of nanocomposite is determined by hysteresis loop. the optimized conditions for the removal of 86% fluoride from field water sample was achieved at ph 8 and in 175 min. from the experimental results, it may be inferred that mnfe2o4 /banana peels composite is an adequate adsorbent for the removal of fluoride from water. keywords: fluoride removal mnfe2o4/banana peels composite co-precipitation method m-h loops adsorption study © 2022 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: qamar1980@hotmail.com 1. introduction asian countries mainly depends upon the ground water for their water source (kazi, brahman, baig, & afridi, 2018; raj & shaji, 2017). the fluoride content enters into this ground water contain fluoride contents due to the natural sources like leaching of fluoride bearing rocks and minerals (viswanathan & meenakshi, 2010).fluoride due to its ubiquitous property is added to the environment anthropogenically varies its contents in lithosphere from 100 to 1500 g/ton (maheshwari, 2006). its dual influences i.e. lower and higher absorption by human being make it of prime importance. fluoride’s specific amount is not only beneficial for human in bone forming, prevention of tooth decay but on the other hand its higher concentration causes fluorosis, brattling of bones, curvature of bones, dwarfishness, mental derangements, cancer, etc. and in extreme cases even death (viswanathan & meenakshi, 2008). it is approximated about 450 million people of 30 countries using water for drinking of more than 1.0 mg/l fluoride contents which is not according to the standards of world health organization who i.e. slightly above or below 1 mg/l. in lower water intake regions, up to 1.5 mg/l fluoride level is acceptable (chen et al., 2016). there are various methods which are difficult in operation, highly expensive and time consuming for the removal of fluorides from water such as chemical precipitation, adsorption technique through batch and column process, ion exchange, nanofiltration, electrodialysis, membrane separation, electrocolactose of plants (dongare et al., 2017) agulation, and reverse osmosis (aldaco, irabien, & luis, 2005), (turner, binning, & stipp, 2005), (cai et al., 2015), (tor, danaoglu, arslan, & cengeloglu, 2009), (onyango, kojima, aoyi, bernardo, & matsuda, 2004), (tahaikt et al., 2007), (lahnid et al., 2008), (behbahani, moghaddam, & arami, 2011), (schneiter & middlebrooks, 1983), (dash, sahu, sahu, & patel, 2015). in this work we use the manganese ferrite (mnfe2o4) /banana peels https://journals.internationalrasd.org/index.php/jmps mailto:qamar1980@hotmail.com https://en.wikipedia.org/wiki/laccase journal of materials and physical sciences 3(2), 2022 72 composite for the removal of fluoride. bananas are internationally known as eatable fruits with yearly cultivated up to one hundred and sixty five million tons in year 2011 (van thuan, quynh, nguyen, & bach, 2017). more often, skin of banana includes 6-9% protein and 20-30% fibers. there are 30% and 15 % more free sugar and starch in ripe banana peels than green banana peels. the assistances of banana coverings were recognized for water cleansing to reduce ethyl alcohol, cellulose, (deshmukh et al. 2017; kumar et al. 2011). but the use of banana peels through batch adsorption is a time consuming and costly process because all operating variables remains constant by changing one variable at a time. the present work is aimed at facile synthesizing an efficient and economical composite of manganese ferrite (mnfe2o4) /banana peels for the removal of fluoride contents. 2. experimental procedure 2.1. chemicals and reagents manganese(ii) chloride tetra hydrate (mncl2. 4h2o, purity ≥ 99%), ferric chloride hexahydrate (fecl3. 6h2o, purity =97%), ferric sulphate heptahydrate (feso4.7h2o, purity ≥ 99%), sodium hydroxide (naoh, purity =97%), acetic acid (ch3cooh, purity ≥99.7%), trisodium citrate dihydrate (na3c6h5o7.2h2o, purity =99.9%), were purchased from merck (germany). ammonia solution (nh3, purity ≥ 99.98%), potassium hydroxide (koh, purity ≥ 85%), sodium fluoride (naf, purity ≥99), sodium chloride (nacl, purity ≥99%) were obtained from sigma-aldrich (germany). 2.2. preparation of magnetic mnfe2o4 particles the magnetic nanoparticles were prepared through the chemical co-precipitation method by dissolving 0.1m solutions 4.95g mncl2 .4h2o, 6.758g fecl3.6h2o, and 0.2m solution of 13.901g feso4.7h2o in 250 ml of deionized water under a nitrogen gas flow with constant stirring at 80℃. the precipitating reagent ammonia solution was continuously added until ph reached 10 ~ 11. the precipitates are formed when ph is maintained. these precipitates were separated by using centrifugation machine. these precipitates were centrifuged, washed two to three times with deionized water. then these are dried into the electrical oven for 24h at 60oc. solid material was then grinded with pestle mortar into a fine powder form of mnfe2o4. the fine powder of mnfe2o4 were annealed by heating in an electrical furnace at 650oc for 240min at the rate of 6oc per min. 2.3. synthesis of banana peels banana peels are collected from banana taking from fruit store. banana peels are washed two or three times to remove impurities by using simple tap water. then banana peels are dried for two days under sunlight. furthermore, these are dried in an oven at the temperature of 100oc for 36h. banana peels were grinded to form a fine powder with the help of simple grinder to form fine powder. 2.4. preparation of mnfe2o4 /banana peels composite mnfe2o4 /banana peels composite was prepared by physically mixing the fine powders 1g of mnfe2o4 and 1g of fine powder of banana peels and then grinding in pestle mortar at room temperature for 30℃. 2.5. adsorption experiments the adsorption experiment was carried out by controlling variables such as contact time (min), concentration (ppm) and ph. batch absorption experiments are performed in 15 ml of centrifuge tubes containing 10mg of mnfe2o4, 5ml deionized water, 2ml buffer solution and 3ml of water sample containing fluorides, 10 mg mnfe2o4, contact time was (5-240 min) and ph was adjusted (3-11) by adding 0.1m hcl and 0.1m naoh. then flasks were shaken at 150rpm in a shaker for 30min. than check it the concentration of fluoride absorbed from fluoride selective electrode by manganese ferrite nanoparticles. the adsorption capacity (mg/g) of the experimental adsorbent was calculated by using by eq. qe = (ci cf)x v/m, where c is concentration in (mg/l), qe is maximum adsorbed quantity at equilibrium, m is mass of adsorbent in (g) and v is volume of solution. https://en.wikipedia.org/wiki/tonne https://en.wikipedia.org/wiki/ethanol muhammad ahsan shafique, z. zaheer, s. sharif, h. taskeen, s. a. shah, athar naeem akhtar, g. murtaza 73 2.6. instrumentation the adsorbent characterization and fluoride ion concentration from aqueous solution was determined by using scanning electron microscope (sem), x-ray diffraction analysis (xrd), fourier transform infrared spectroscopy (ftir), ion selective electrode and hysteresis loop for the softness of material and fluoride sensor for adsorption tests. 3. results and discussion 3.1. xrd analysis the crystallinity and purity of as synthesized magnetic manganese ferrite composite were evaluated by powder xrd. all diffraction peaks of xrd pattern is indexed to face centered cubic structure (fig. 1). the sharpness of diffraction peaks is confirming the crystallinity of our synthesized material without any impurities. the x-ray pattern of as prepared manganese ferrite composite depicts the peaks at (111), (220), (311), (222), (400), (422), (511), (440) which are exact corresponding peaks of magnetic manganese ferrite, as confirmed by literature. these peaks are clearly confirming the structure of our as prepared manganese ferrite formation. all lattice parameter values such as, cell unit volume ‘a’ and xray density of sample was calculated by using this formula )( 3 222 2 2 2 lkh a sin ++=   (1) where λ is the wavelength, h,k,l are the miller indices and a is the lattice constant. i.e. a= 8.25 å v=a3 (2) dx = 8 m/na v (3) here m is molar mass, na is avogadro number, v is unit cell volume and 8 is number of molecules per unit cell. 10 20 30 40 50 60 70 80 220 111 in te n s it y ( a .u ) 2-theta (degree) 311 222 400 422 511 440 figure 1: xrd patterns for single phase mnfe2o4 ferrite synthesized by coprecipitation method journal of materials and physical sciences 3(2), 2022 74 the arrangement/geometry of atoms and unit cell size is measured by angular positions and relative intensities of diffracting peaks. 3.2. ftir analysis ftir spectrum of both simple mnfe2o4 were taken which reveals the similarity of spectrum of both mnfe2o4 and our as prepared materials, which confirms that our prepared nanocomposite is formed properly as confirmed by its representing characteristics peaks. ftir spectrum of simple manganese ferrite is taken and its characterization peaks are observed at 3377 cm-1 , 1980 cm-1, 1378 cm-1 due to mn-o-fe stretching, 661cm-1 due to fe-o and mn-o bonds (fig. 2). 4000 3500 3000 2500 2000 1500 1000 500 -0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 a b s o rb a n c e wave number (cm -1 ) mnfe 2 o 4 661 1378 3377 1980 figure 2: ftir spectrum of simple manganese ferrite ftir spectrum of as prepared manganese ferrite composite is shown in fig. 3. the spectrum shows four characteristic absorption bands which clearly indicate the formation of manganese ferrite. the peak at 660 and 66 cm-1 are an evidence for the presence of fe-o and mn-o bonds. the absorption band at 1378 cm-1 represents the mn-o-fe stretching whereas the peak at 1980 cm-1 is an indication of double bond character of metal-oxygen bond which may be attributed to fe=o double bond in the manganese ferrite. the broad absorption band at 3377 cm-1 may be attributed to o-h stretching mode of certain water moieties associated with the manganese ferrite. the stretching vibrations values given below in spectrum clearly depicts the synthesis of as prepared manganese ferrite with banana peels for the removal of fluoride ions from real water samples. table 1 representing functional groups stretching values sr. no. functional group absorption frequency 1 o-h stretching 3377 cm-1 2 mn-o-fe stretching 1378 cm-1 3 fe=o bond 1980 cm-1 4 fe-o 661 cm-1 muhammad ahsan shafique, z. zaheer, s. sharif, h. taskeen, s. a. shah, athar naeem akhtar, g. murtaza 75 figure 3: ftir spectrum of mnfe2o4 composite spectrum of our prepared manganese ferrite composite given below, whose similarity with that of simple manganese ferrite spectrum shows that our prepared mnfe2o4 composite accurately had synthesized. 3.3. magnetic measurements magnetic measurements were carried out of our as prepared material with vibrating sample magnetometer and its hysteresis loop was obtained. these measurements were carried out for investigating the magnetic properties of that as prepared material. the hysteresis loop is exhibiting the soft magnetic nature of our material, as very small area occupied by closed curve is basically related to soft magnetic materials properties (fig. 4). these properties are dependent upon sintering temperature, metal ions in ferrite structure and preparation methods. -8000 -6000 -4000 -2000 0 2000 4000 6000 8000 -30 -20 -10 0 10 20 30 m a g n e ti z a ti o n ( e m u /g ) magnetic field (oe) ms = 30.28 emu/g mr = 6.70 emu/g hc = 286 oe figure 4: hysteresis loop of single phase mnfe2o4 ferrite synthesized by coprecipitation method journal of materials and physical sciences 3(2), 2022 76 magnetic moment value of the sample was calculated by magnetization saturation data by given formula (raghuvanshi, satalkar, tapkir, ghodke, & kane, 2014). the calculated data is in full agreement to the saturation magnetization as both the parameters are directly related to each other. nb (µb) = m ×ms / 5585 (4) where nb is magnetization moment, m is the molecular weight of sample, ms is saturation magnetization and hc is coercivity of manganese ferrite. 3.4. adsorption study for exploring the adsorption performance and for ensuring the reliability, accuracy and reproducibility of our material, adsorption experiments were carried out. adsorption removal studies for removing fluoride by both simple manganese ferrite and our magnetic manganese ferrite composite were investigated and compared the capabilities of our materials. 3.4.1.factors affecting adsorption the following two parameters i.e., time and ph were carried out for adsorption studies. 3.4.1.1. effect of contact time the data obtained from different contact time experiments by both materials i.e., mn2feo4 and mn2feo4/banana peels were plotted in fig. 5. from fig, it can be clearly observed that adsorption removal efficiency increased with contact time till 175 min, then equilibrium constant value was achieved. this was probably due to the abundant adsorption sites of our composite material at initial states (wang et al., 2022), as the interaction sites becomes occupied with passage of time, adsorption of fluoride becomes lower by adsorbent (wang et al., 2022). when the equilibrium is achieved, all sites become fully saturated. the optimum time for equilibrium is 175 min. as it is much more efficient in adsorption removal of fluoride ion as compared to simple manganese ferrite. the fluoride specific amount of uptake (qt), was determined by given formula i.e. qt = v (co – ct) / w (5) and the percentage removal efficiency of fluoride was calculated by % adsorption = 100 × (co – ct) / co (6) where co (mg/ l) is initial concentration, ct (mg/l) is concentration at time t. v is volume (l) of solution and w (g) is mass of adsorbent. after treatment with manganese ferrite for 175 min, total amount of adsorbate after time t (qt), onto adsorbent is maximum in case of our composite i.e., 8.9 value is being calculated. as qt is total amount of fluoride ions uptake after time t. the results obtained by this study in table 2 as given below. table 2 effect of contact time on removal of fluoride mnfe2o4 time (min) 5 10 15 30 60 175 180 240 qe (mg/g) 2.9 3.9 4.1 8.3 8.6 8.7 5.7 4.9 mnfe2o4/banana peels qe (mg/g) 3.4 4.2 5.9 8.6 8.7 8.9 6.1 5.2 muhammad ahsan shafique, z. zaheer, s. sharif, h. taskeen, s. a. shah, athar naeem akhtar, g. murtaza 77 0 50 100 150 200 250 0 2 4 6 8 10 q t (m g /g ) time (min) mnfe 2 o 4 mnfe 2 o 4 /banana peels figure 5: effect of contact time on fluoride removal 3.4.1.2. effect of ph on adsorption capacity (qe) effect of ph on adsorption of fluoride ions on both mnfe2o4 and mnfe2o4 composite was investigated by keeping different ph of same solutions. it reveals the dependence of ph on adsorption capacity of our as prepared material. the adsorption is high at low ph values and low at high ph. this high uptake at low ph was ascribed to high hydrogen ions concentration at lower ph which causes the increase in positive charges at the sorbent surfaces leading to increase amount of fluoride removal. similar results were observed by sahira et al in 2012, while they were removing the same fluoride ions from water by using zirconyl impregnated activated carbon which were prepared by lapsi seed stone. they also noted the same thing that ph had great influence on surface charge of adsorbents as it increased the interaction of fluoride ions with adsorbent (joshi, adhikari, & pradhananga, 2012). at higher ph (> 8), due to presence of higher concentration of hydroxide ions, they hindered the diffusion of fluoride ions which leads to low uptake of the fluoride ions. that hindrance is caused due to repulsive forces occurring between the negative charges of fluoride ions and hydroxide ions. 𝑞𝑒 = 𝐶𝑖− 𝐶𝑓 𝑚 ∗ 𝑉 (7) where c is concentration, qe is maximum adsorbed quantity at equilibrium, m is mass of adsorbent and v is volume of solution. batch experiments results confirmed our biomaterial is given better results at ph 8, i.e.8.9 than that of simple ferrites at the same ph as can be seen by fig. 6. at room temperature (initial concentration ci = 10 mg/l, shaking time = 2h, t = 25 oc, ph = 7 ± 0.1, m = 10 mg and v = 10 ml). journal of materials and physical sciences 3(2), 2022 78 table 4 effect of ph on adsorption removal mnfe2o4 ph 3 4 5 6 7 8 9 10 11 qe (mg/g) 2.9 3.9 4.1 8.3 8.6 8.7 5.7 4.9 3.8 mnfe2o4/banana peels qe (mg/g) 3.4 4.2 5.9 8.6 8.7 8.9 6.1 5.2 3.9 2 3 4 5 6 7 8 9 10 11 12 2 3 4 5 6 7 8 9 mnfe 2 o 4 q e ( m g /g ) ph mnfe 2 o 4 /banana peels figure 6: effect of ph on adsorption removal 3.4.2.real time application it is important to determine the adsorption mechanism which is essential for determining its residence time. the mechanism of adsorption removal from aqueous system by porous adsorbents require four basic steps i.e. 1. migration of ions from aqueous system to boundary layer or film surrounding adsorbents. 2. diffusion of ions to exterior layer of adsorbents known as external diffusion. 3. transport of ions from exterior to interior surface through pore diffusion mechanism. 4. uptake of ions by available sites. the slowest step defines the uptake rate and rate determining step. here in given fig. 7, value of c determines the boundary layer thickness of adsorbent. it provides the understanding of ions either those had been got adsorbed or remained in solution. higher value of c exhibits higher adsorption. table 5 real water sample analysis at room temperature (initial concentration ci = 10 mg/l, t = 25 oc, ph = 7 ± 0.1, m = 10 mg and v = 10 ml) time (min) 5 10 15 30 60 120 180 240 ct (mg/l) 10 9.4 8.1 6.3 4.2 2.1 1.2 0.9 muhammad ahsan shafique, z. zaheer, s. sharif, h. taskeen, s. a. shah, athar naeem akhtar, g. murtaza 79 0 40 80 120 160 200 240 0 2 4 6 8 10 c t (m g /l ) time (min) who limit (1.5 mg/l) mnfe 2 o 4 + banana peels figure 7: effect of time on adsorption tendency of adsorbent conclusion the magnetic material was successfully synthesized and that was confirmed by ftir studies which indicated the existence of the anchored functional groups.it was found to be effective removal up to 86 %. the optimum contact time and ph were found to be 175 min and 8 respectively. fluoride ions cause oxidant effect which is responsible for several diseases like thyroid problems, neurological problems cardiovascular problems reproductive issues and bone cancer. manganese ferrite/banana peel composite is very good fluoride ion adsorber. from our research it is identified that maximum amount of fluoride ions is adsorbed easily by our material. this material had potential application for fluoride removal and is biodegradable, economic and environmentally friendly. it can be beneficial at industrial scale if prepared at bulk scale. references aldaco, r., irabien, a., & luis, p. 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(2022). application of carbon dots and their composite materials for the detection and removal of radioactive ions: a review. chemosphere, 287, 132313. https://doi.org/10.52131/jmps.2023.0401.0031 1 journal of materials and physical sciences volume 4, number 1, 2023, pages 01 08 journal homepage: https://journals.internationalrasd.org/index.php/jmps exploring the potential of zinc ferrite nanocomposite as an anode material in lithium-ion batteries: integration with fish scalederived carbon support for enhanced performance suqqyana fazal1, fawad ahmad1*, khizar hussain shah2, shabnam shahida3, tauqeer ahmad4, gulfam nasar5* 1 department of chemistry, university of wah, quaid avenue, wah cantt., (47010), punjab, pakistan 2 department of chemistry, comsats university islamabad, islamabad campus, islamabad 45000, pakistan 3 department of chemistry, university of poonch, rawalakot, azad kashmir 12350, pakistan 4 department of chemistry, university of mianwali, mianwali 42200, pakistan 5 department of chemistry, faculty of basic sciences, balochistan university of information technology, engineering and management sciences, quetta (87100), pakistan article info abstract article history: received: january 24, 2023 revised: march 04, 2023 accepted: march 28, 2023 available online: june 26, 2023 for lithium-ion batteries, excellent anode materials are recognized as ternary zinc-based oxides. due to metal oxides' poor cycling stability, rapid capacity deterioration, and poor rate performance, their use as battery anodes reduces their applicability. however, by reducing the material's particle size and loading it on activated and non-activated carbon, the electrochemical performance gets improved. znfe2o4 is prepared hydrothermally and analyzed by an x-ray diffractometer to determine the znfe2o4 pure phase. sem data shows that the particle's diameters ranged from 20 to 140 nm. its 1015 mah/g capacity after 100 cycles and maintenance cycle stability compared to other anode materials proves it’s an excellent anodic material for lithium-ion batteries. keywords: lithium-ion batteries zinc ferrite electrochemical analysis xrd sem © 2023 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding authors’ email: fawad.ahmad@uow.edu.pk, gulfam.nasar@buitms.edu.pk 1. introduction due to their extended cycle life and high energy density, lithium-ion batteries (also called lib) are viewed as viable new power sources for portable electronic gadgets as well as for electric hybrid cars. the dendritic lithium development on the surface of the anode at high charging current would be one of the significant safety concerns in libs for hybrid electric vehicles since the traditional carbonous material approaches nearly zero v versus li/li+ towards the conclusion of li insertion (cheng, shapter, li, & gao, 2021). the lithium battery cannot function without the anode. the anode material currently has greater opportunities for advancement than the cathode material. graphite, the primary anode material currently in use, has an inadequate specific capacity and cannot satisfy consumer demand for high-performance lithium batteries (divakaran et al., 2021). transition metal oxide electrodes, such as zno, mno, fe2o3, and nio, have outstanding cycle performance, flexible operating voltage, and high theoretical specific capacities (500–1000 mahg-1) (athika et al., 2019; orisekeh et al., 2021). tmo anode materials provide better stability and specific capacity when compared to commercially available graphite anodes since they can prevent lithium dendrites (zhang et al., 2021). it costs less to produce alloy anode materials than metals. however, numerous issues still need to be resolved, such as electrolyte decomposition (tsai, kuo, liu, lee, & yew, 2021). due to the synergistic properties of iron along with the other transition metal presence, spinel mixed transition metal oxides based on iron (mfe2o4, where m = zn, cu, mn, co, etc.) are being suggested as natural alternative anode materials for high-performance lithium-ion batteries (trandafir et al., 2023; ul ain, fazal, & ahmad, 2023). zinc ferrite (zfo), in contrast to other oxides employed, has a lithium insertion process, including alloying and conversion events https://journals.internationalrasd.org/index.php/jmps mailto:fawad.ahmad@uow.edu.pk mailto:gulfam.nasar@buitms.edu.pk journal of materials and physical sciences 4(1), 2023 2 (appiah‐ntiamoah, baye, & kim, 2020). zfo is very interesting because of its low cost, abundant supply of eco-friendly zn and fe elements, large surface-to-volume ratio, relatively short path for li-ion diffusion, the low working voltage of about 1.5 v for lithium extraction, and, most importantly, high theoretical specific capacity (1072 ma h g-1) (jiang et al., 2018; nivetha & grace, 2019). however, znfe2o4 suffers from the same issue as other anode materials in that it is susceptible to significant volume expansion during the insertion and removal of lithium ions (bini, ambrosetti, & spada, 2021; spada et al., 2023). volume change results in cracking, crushing, and even separating some active ingredients from the collector, which affects the battery's ability to cycle and charge quickly and how much capacity it can hold (li et al., 2019). the iron-based anode material's particle size is decreased to the nanoscale level to alleviate this issue and provide stable battery operation. as a result, physical stress may be decreased, nanomaterials' lithium-ion battery reaction times can be sped up, the ion diffusion channel can be condensed, and the specific surface area can be raised to ensure that the electrode material makes complete contact with the electrolyte (lv, wang, zhang, shi, & shi, 2022). due to carbon's porous structure, its presence can offset some of the adverse effects of zfo's volume alterations (ghule, shaikh, & mane, 2020). as a result of their chemical composition, fish scales are one of the most promising carbon sources (zingare, dhoble, & deshmukh, 2022). these are a cheap and convenient source of carbon-free biomass because of easily accessible. in this research, fish scale-derived carbon (fsc) is added as an amorphous skeleton, and by using a hydrothermal process, the heterostructure of zinc ferrite is anchored to the rhc matrix. one of them, a matrix of carbon made of biomass, is anticipated to reduce the volume that expands nanoparticles of oxide during charge and discharge while also enhancing the conductivity of the active material. a sample of zinc iron oxide is made without using the carbon nanocomposites method and then heated in an argon environment. following that, measurements using cyclic voltammetry, lsv, eis, and x-ray diffraction are made to connect the identified structural, morphological, and electrochemical features. 2. materials and synthesis zinc nitrate hexahydrate, iron nitrate hexahydrate, hydrochloric acid, sodium hydroxide. ammonia water, urea, ethanol, and fish scales were used for the synthesis. 40 mmol urea was dispersed into a solution of 100ml distilled water and 100ml ethanol. the solution was marked as solution a, and solution a was fully stirred. 4mmol zinc nitrate hexahydrate and 4mmol iron nitrate hexahydrate were dispersed in a solution of 50ml distilled water and 50ml ethanol. the solution was stirred for 30 minutes and named solution b. solution b was slowly dripped into solution a, then 15ml of ammonia water and 20ml distilled water were added to it. the mixed solution was stirred for half an hour. after stirring for half an hour, the solution was transferred to a 500 ml china dish, maintained at 130 °c for 12 h. the obtained solution was washed three times with distilled water and ethanol until neutrality was achieved. 2.1. preparation of activated carbon labeo rohita (rohu) fish scales were taken from the market. tap water was used for washing, and hot and cold distilled water was used to remove dirt and impurities. then, they were shelter dried thoroughly for three days. using a mixer grinder, they were broken into tiny pieces. the percentage of crushed material that passed through a 600 m sieve but was kept on a 125 m screen was collected. it was then converted to charcoal in a muffle furnace at 600ºc. this material was then chemically activated by acid/base treatment. acid activation was performed using 10g of fish scale powder combined with 150 ml 0.1m hcl solution for 2.5 hours at room temperature on a 100rpm heating plate. base activation was also performed as same using 0.1m naoh. it was then vacuum filtered, obtained semislurry, and rinsed with distilled water until it reached ph=7. after that, the sample was oven-dried at 60º celsius. the prepared activated carbon material was cooled and stored in a desiccator. suqqyana fazal, fawad ahmad, khizar hussain shah, shabnam shahida, tauqeer ahmad, gulfam nasar 3 2.2. preparation of znfe2o4/ac zinc ferrite nanocomposite and activated carbon from fish scales were combined in a 3:7 ratio, dissolved in 30 ml of distilled water, and agitated for 30 minutes. the prepared sample was moved into a 50 ml china dish and treated there for 24 hours at 200 °c before being twice washed using ethanol and distilled water. the dried prepared material was placed at 60 °c in the oven. this item was identified as znfe2o4/ac. 2.3. preparation of znfe2o4/nac zinc ferrite nanocomposite and non-activated carbon from fish scales were combined in a 3:7 ratio, dissolved in 30 ml of distilled water, and agitated for 30 minutes. the prepared sample was moved into a 50 ml china dish and treated there for 24 hours at 200 °c before being twice washed using ethanol and distilled water. the dried prepared material was placed at 60 °c in the oven. this item was identified as znfe2o4/nac. 3. results and discussion 3.1. xrd analysis the xrd method was used to conduct a crystallographic examination of the synthesized material. the xrd graphs for the zinc ferrite nanocomposites and zfo/c samples are shown in the figure. the absence of specular diffractions denotes crystallographic purity (kiruthika, lakshmi, diana, helen, & selvin, 2022). it confirmed that the synthesized substance is pure because no impurity peaks were seen. the xrd peaks corroborated the formation of zfo (220), (311), (400), (422), (333), (440), at 30.01, 35.43,42.98, 53.21 56.81, and 62.16 described in the literature as shown in fig 1(a) (parvathi & ramesan, 2023). the data determined the crystallite size to be 22.49 nm. the intense diffraction peaks are the key evidence for the current sample's excellent crystallinity. figure 1: (a) xrd of zfo and zfo/ac (b) tga of zfo (c) tga of zfo/ac furthermore, all the peaks appearing in the xrd pattern are attributed to zinc iron oxide. no additional intermediate states, such as zno and fe2o3, are detected, indicating journal of materials and physical sciences 4(1), 2023 4 the complete chemical reaction. an expert high score has been used, and the position and relative strength of the diffraction peaks agree well with the conventional zinc iron oxide diffraction data (jcpds221012), as shown in the image. the formation of the zfo/c nanocomposite is made apparent by sharp peaks given by the sample zfo/c than by pure zinc ferrite nanocomposite (baynosa et al., 2020). according to zfo's tga data, zinc ferrite degrades in a single step between 200 and 500◦c, losing 5.8% of its zinc content as coordinated metal connections break (karthikeyan, sirajudheen, nikitha, & meenakshi, 2020). on the other hand, zfo/c degrades in three steps and becomes steady above 320◦c. 3.2. sem analysis high-resolution sem examination was used to evaluate the surface shape and grain size of the synthesized zfo/c nanocomposite. the granules in the figure are evenly dispersed shown in fig 2(c). agglomeration might arise as a result of magnetic interaction between nanoparticles. aggregation of smaller grains is also conceivable, giving birth to grain boundary regions that may be seen distinctly at the outer edges of some of the grains. the maximum and minimum particle sizes calculated through nano measure are 141.56nm and 15.69nm under a 500nm scanning lens. the average number of particles present is 76.18nm. the maximum and minimum particle sizes calculated through nano measure are 0.34um and 0.07um under a 1um scanning lens. the average number of particles present is 0.19um. the average particle shape is irregular, but the size is uniform, as shown in fig 2(a). a b c d figure 2: (a)(b) sem and distribution plot at 1µm scanning lens (c)(d) sem and distribution plot at 500nm scanning lens suqqyana fazal, fawad ahmad, khizar hussain shah, shabnam shahida, tauqeer ahmad, gulfam nasar 5 3.3. electrochemical studies to evaluate the electrochemical characteristics of zinc ferrite nanocomposite and its sample with non-activated carbon support and activated carbon support, each sample was independently coated on the glassy carbon electrode (working electrode). the broad minor tumid at about 1.1 v creates a solid-electrolyte interface (sei) as an outcome of the electrolyte decomposition. a 0 1 2 -3.5x10 -5 -3.0x10 -5 -2.5x10 -5 -2.0x10 -5 -1.5x10 -5 -1.0x10 -5 -5.0x10 -6 0.0 5.0x10 -6 1.0x10 -5 1.5x10 -5 2.0x10 -5 c u rr e n t (a ) pottential applied vs rhe 10mv/s 50mv/s 150mv/s 200mv/s 300mv/s b 1.0 1.5 2.0 0.0 5.0x10 -6 1.0x10 -5 c u rr e n t (a ) applied pottential vs rhe c 0 50 100 150 200 250 300 200 400 600 800 1000 1200 s p e c if ic c a p a c it y scan rate d figure 3: (a) cv of zfo (b) lsv of zfo (c) sr vs. specific capacity (d) eis of zfo, zfo/nac, and zfo/ac the most pronounced strong reduction peak at 0.9 v is caused by the irreversible reduction of zn2+ and fe3+ from the lixznfe2o4 crystals to metal zn and fe and the alloying process of zn to lizn. the anodic curves, however, continue to have the same general shape. as there is no loss of li+ from the lizn alloy, no mild oxidation peak is shown between 0.14 and 0.26 v (xu et al., 2021). the noticeable oxidation peak is then found at 1.20-1.98 v, caused by the reversible conversion of zn and fe metals to zno and fe2o3 (wei et al., 2019). an outline of all potential anode reactions from equations (1-5). journal of materials and physical sciences 4(1), 2023 6 znfe2o4 + xli+ + xe→ lixznfe2o4 (1) lixznfe2o4 + (nx)li+ + (nx)e → zn + 2fe + 4li2o (2) zn + li+ + e↔ lizn (3) zno + 2li+ + 2e ↔ zn + li2o (4) fe2o3 + 6li+ + 6e ↔ 2fe + 3li2o (5) from lsv, 0.98v was determined as the onset potential fig 2(b). the electrochemical events of reduction, oxidation, lithiation, delithiation, and sei production for zfo/c are identical to those in zinc ferrite nanocomposite (bao et al., 2021). the greater surface area of cv in fig 4(a)(b) demonstrates the difference in improved electrocatalytic activity attributed to the existence of porous carbon (lee, ahn, & lee, 2022). a 0 1 2 -2.0x10 -5 -1.0x10 -5 0.0 1.0x10 -5 2.0x10 -5 c u rr e n t (a ) applied pottential vs rhe 200 scan rate 50 scan rate b 0 1 2 -6.0x10 -5 -4.0x10 -5 -2.0x10 -5 0.0 2.0x10 -5 4.0x10 -5 c u rr e n t (a ) applied pottential vs rhe 50 scan rate 200 scan rate figure 4: (a) cv of zfo/nac (b) cv of zfo/ac the calculated values of specific capacity given above show that due to the greater surface activity of activated carbon zfo/ac has the highest specific capacity (he, wang, tang, zhang, & wang, 2022). greater charge storing capacity tends to have greater columbic efficiency of zfo/ac (liu et al., 2022). table 1 specific capacity at 50mv/s, current density, ecsa, and columbic efficiency of prepared materials material specific capacity at 50mv/s current density (μacm-2) ecsa columbic efficiency zinc ferrite 748.8mah/g 398.69 3.14e-02 74% zinc ferrite/nac 882mah/g 296.09 3.32e-02 89% zinc ferrite/ac 1115.6mah/g 619.84 7.70e-02 98% eis was used to verify the developed material's conductivity further. figure 2(d) displays the nyquist plots as obtained, which are divided into linear and several semicircle sections. the inclined straight line is in the low-frequency band, while the semicircular region belongs in the higher frequency range. the intersection point, which is present at higher frequencies, provides information about "rs," which stands for the material resistance that electrodes have by nature and the conflict that results from the contact of the working electrode with the collector. diffusion resistance is provided by the straight line in the second section of the nyquist plot. of the linear line's more vertical nature, this resistance decreases (zhao et al., 2022). compared with zfo/nac and zfo/ac materials, bare zfo has displayed a larger semicircle, suggesting that it offers strong solution resistance. rise in the fictional portion of the plot demonstrated that the produced material performed well in terms of conductivity. the rise in the fictitious portion of the curve is more pronounced for zfo/ac nanocomposite, showing that the electrode's material is more conducting than electrodes built of zfo and zfo/nac. after the first ten cycles, there is a noticeable decline in specific capacity and colombic efficiency, but stability is maintained for the following 100 cycles shown in fig 5. suqqyana fazal, fawad ahmad, khizar hussain shah, shabnam shahida, tauqeer ahmad, gulfam nasar 7 0 20 40 60 80 100 1000 1020 1040 1060 1080 1100 1120 1140 specific capacity ce cycles s pe ci fic c ap ac ity (m a hg -1 ) 74 75 76 77 78 79 80 c ol ou m bi c ef fe ci en cy figure 5: cyclability of zfo conclusion the hydrothermal synthesis approach was used to create the znfe2o4 nanocomposites, which were also supported by carbon from fish scales. the current investigation results are completely coordinated with the standard chemically routed znfe2o4/c samples. the xrd results show a crystalline structure with no traces of impurities, and the crystallite size is 23 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(2022). highly stable fish-scale derived lamellar carbon for high performance supercapacitor application. diamond and related materials, 124, 108925. https://doi.org/10.52131/jmps.2020.0102.0008 78 journal of materials and physical sciences volume 1, number 2, 2020, pages 78 86 journal homepage: https://journals.internationalrasd.org/index.php/jmps comparison of thermoelectric properties of zno and znsno thin films grown on si substrate by thermal evaporation u. rehman1, k. mahmood1*, a. ali1, s. ikram1 1 department of physics, government college university faisalabad article info abstract article history: received: october 13, 2020 revised: november 08, 2020 accepted: december 06, 2020 available online: december 31, 2020 in this manuscript, we compared the thermoelectric properties of zno and znsno thin films grown on silicon (100) substrate. we have evaporated zn and sn+zn metal powders were evaporated in vacuum tube furnace alternatively, under same experimental conditions for the growth of zno and zto respectively. after the deposition, these grown films were cut into pieces and post growth annealed at different annealing temperatures from 600oc to 800oc in the air using programmable muffle furnace. seebeck and hall data suggested that zto sample shows highest value of seebeck coefficient, electrical conductivity and power factor as compared to the zno samples. it is also observed that the value of seebeck coefficient showing an increasing trend for both of the samples as we increase the post growth annealing temperature. the higher thermoelectric properties for zto are due the presence of sn atoms in zno structure. tin dopants may generate secondary phases and/or enhanced the carrier mobility which might be the reason that zto has improved thermo-electric properties as compared to zno. xrd and raman measurements were used to confirm the formation of zto. xrd data verified the hexagonal structure of zno but a slight red shift is observed for the case of zto samples. to further justify our argument, we have also performed raman spectroscopy measurements which confirmed the presence of sn elements in zto. keywords: zno zto seebeck coefficient power factor post growth annealing © 2020 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: khalid_mahmood856@yahoo.com 1. introduction high temperature thermoelectric materials are getting much interest, especially for the utilization of waste heat from thermal power plants, factories and radioisotope thermoelectric materials for space applications (kristiansen, barragán, & kjelstrup, 2019; mirhosseini, rezania, & rosendahl, 2019; yuan et al., 2019). however, the real-time applications of many of the thermoelectric materials are limited because of their phase transition at elevated temperatures (ng et al., 2019). oxide based thermoelectric materials are getting much interest because they are chemically stable at high temperature (manickam & biswas, 2019). zno with a wide band gap (3.3 ev) and n-type conductivity is widely used in many electronic applications such as: optical devices, piezoelectric devices, transparent electrode layer for solar applications, integrated circuits and gas sensors (abed, ali, addad, & elhouichet, 2019; arrabito, errico, zhang, han, & falconi, 2018; kumar, jeong, & lee, 2019; novak et al., 2019; r et al., 2018). beside this, such a wide band gap of zno is beneficial for preventing thermal excitation of the carriers. due to its unique properties, zno is getting popular for thermoelectric applications, but lower electrical conductivity value limited its applications (zahra, mahmood, et al., https://journals.internationalrasd.org/index.php/jmps mailto:khalid_mahmood856@yahoo.com u. rehman, k. mahmood, a. ali, s. ikram 79 2019). the incorporation of some impurity atom is an easy way to engineer the properties of any material. in addition, insertion of several kinds of donor impurities has been reported so far such as: al, ga, cu, ni, ge, in, sn, mn and many others to improve the thermoelectric properties of zno (aboud, shaban, & revaprasadu, 2019; ardyanian, moeini, & azimi juybari, 2014; jayathilake, sagu, & wijayantha, 2019; paul, khranovskyy, yakimova, & eklund, 2019; teehan, efstathiadis, & haldar, 2011; zahra, jacob, et al., 2019). the performance of thermoelectric material can be expressed by seebeck coefficient ( )vs t =  , power factor ( 2 *p s = ) and dimensionless figure of merit (zt) which is given by 2 ( )s tzt =  (ali et al., 2019; ashfaq et al., 2019; jacob et al., 2019; mahmood, abbasi, zahra, & rehman, 2018). where s, σ and k are seebeck coefficient, electrical conductivity and thermal conductivity respectively. tin is supposed to be a donor impurity to improve the electrical and thermoelectric performance of zno (zhang et al., 2019). in addition, both zn and sn have almost equal atomic radii make it easy to replace zn with sn atom without any degradation in crystal quality. ajili et al. studied the doping effect of sn on zno and found that 0.6% sn doping significantly enhance the hall mobility 9.22 cm2/vs and resistivity value upto 8.32×10-2ωcm (ajili, castagné, & turki, 2013). recently, rehman et al. has reported the direct growth of znsno (zto) nanowire by thermal evaporation and found that the value of seebeck coefficient and electrical conductivity was increasing from 220 to 498 µv/oc and 89 to 283 (s/cm) by increasing the post annealing temperature (rehman et al., 2019). in this research work, we make a comparison of the thermoelectric properties of zno an zto thin films grown on silicon substrates by thermal evaporation technique and studied the effect of incorporation of sn and post growth annealing effect on zno. xrd measurements were performed to understand the structural properties which confirm the formation of hexagonal structure. while the seebeck coefficient and electrical conductivity are found to be increasing with the addition of sn and post growth annealing temperature. 2. experimental detail in this research work zno and zto thin films were deposited by thermal evaporation technique by using horizontal glass tube furnace. initially for zno film, 99% pure zinc powder (0.1g) and for zto; zinc and tin metal powder (10:1) were evaporated on the single crystal silicon substrate. the detail of experimental work is reported elsewhere (rehman et al., 2019). after the deposition, samples were cut into rectangular pieces and post growth annealed at different annealing temperatures from 600oc to 800oc at atmospheric pressure in programmable muffle furnace. finally, samples were characterized by different tools. structural characterization of the grown thin film was performed by x-ray diffraction (bruker d8 advanced) with cukα source having wavelength 0.154nm. raman spectroscopy was carried out using mn stex-pr1100 to study the vibrational and rotational modes of the grown film. the surface morphology of the prepared samples was characterized by emcraft scanning electron microscope (cube-series). the seebeck coefficient was measured by the homemade seebeck system. the thickness of as grown sample was calculated by thickness meter (filmtronics) and it was found to be 0.5μm. the detail of the equipment with model number and specifications were already reported in our previous work (ali et al., 2019). 3. result and discussion figure 1 (a, b) depicts the effect of post growth annealing and measurement temperature on the seebeck coefficientof zno and zto thin films grown on silicon (100) substrate. the values of seebeck coefficient for all samples have negative values, showing the n-type behavior for both thin films. the data evident that the value of seebeck coefficient has shown an increasing trend with annealing temperature for both samples. this behavior of seebeck coefficient is due to the fact that oxygen atoms diffused to interstitial sites by getting thermal energy due to high annealing temperature which resulted in the increase of seebeck coefficient. it is accepted fact that annealing temperature filled the oxygen vacancies for example reported by asghar et al (asghar, mahmood, & hasan, 2012). even further annealing causes diffusion of oxygen atoms to journal of materials and physical sciences 1(2), 2020 80 interstitials sites. therefore, for the verification of oxygen vacancies we have performed pl measurements on representative sample shown in figure 2. the graph showed a defect emission peaks. it is believed that defect emission at 2.3 ev is related to the transition from oxygen vacancy to valance band. the graph showed that defect emission decreases as the annealing temperature increases from 600 to 800 0c because number of oxygen vacancies were filled by incoming oxygen atoms during annealing process. here we claimed that the addition of donor impurity increases the value of seebeck coefficient in zno metrics. on the other hand, high temperature annealing also causes intrinsic impurity defects and shift scattering mechanism from lattice to impurity scattering mechanism. hence, carriers are more mobile at high measurement temperature and easily move from hot to cold end so this kind of enhancement in seebeck coefficient is expected. in recent the same kind of behavior was already reported by our group (jacob et al., 2019). figure 1: seebeck coefficient of post annealed(a) zno and(b) zto thin films at different temperatures ranges from 600-800oc for 60 min at different measurement temperature figure 2: room temperature pl spectra of zno thin films annealed at various temperatures u. rehman, k. mahmood, a. ali, s. ikram 81 figure 3 (a, b) represents the effect of annealing temperature on electrical conductivity of the zno and zto thin films grown on si substrate. it is clearly seen that electrical conductivity shows an increasing trend with the annealing temperature. furthermore, zto samples show slightly higher electrical conductivity as compared to zno. it can be explained as; zno exhibits high electrical conductivity due to the presence of oxygen vacancies acting like a donor state, while the addition of donor impurity can further assist to improve the electrical conductivity. here in this case addition of sn4+ atom behaves as a doubly ionized donor state so this increase in electrical conductivity is expected (ruzgar & caglar, 2019). figure 3: electrical conductivity of post annealed(a) zno and (b) zto thin films at different temperatures ranges from 600-800oc for 60 min at different measurement temperature the effect of annealing temperature on power factor of zno and zto samples annealed at different annealing temperature is shown in figure 4 (a, b). as electrical conductivity and seebeck coefficient increased with annealing temperature so increase in power factor for both samples is understandable. as the xrd and raman data (explained later) have confirmed the presence of sn atoms into the zno sample. these sn atoms act like donor defects in the zno crystal, therefore enhanced the carrier concentration. this enhancement in carrier concentration resulted in the enhancement of seebeck coefficient and power factor. figure 4: power factor of post annealed (a) zno and (b) zto thin films at different temperatures ranges from 600-800oc for 60 min at different measurement temperature figure 5 (a, b) demonstrated the xrd pattern of zno and zto samples at different post growth annealing temperatures. the xrd pattern of post growth annealed samples shows five diffraction peaks. the peak at 31.94o, 34.63o, 36.41o, 47.71o and 56.86o are journal of materials and physical sciences 1(2), 2020 82 related to (100), (002), (101), (102) & (110) which are belongs to wurtzite hexagonal zno phase (ullah, amin badshah, raza, altaf, & hussain, 2011). while in the case of zto, the diffraction pattern shows the same trend as that of zno. no other secondary phases related to sno and sno2 are observed with the addition of the impurity atoms in zno crystal. only a slight shift toward the higher angle is observed for zto sample as compare to the pure zno sample. this behavior is attributed as: when larger radii atom (zn=74 pm) is replaced with the smaller radii atom (sn=70 pm) this red shift is expected (ajili et al., 2013). to strengthen our argument and to verify the presence of sn, we perform raman spectroscopy measurements (latterly discussed). in fig. 4 (a) the plane along (101) shows the maximum intensity for zno while in case of zto the preferred peak along (002) is observed fig. 5 (b). this means these planes are sensitive to the oxygen which is already reported in literature (chahmat et al., 2014). it is clearly seen that crystallinity of the film is decreased as the post growth annealing temperature is increased. this could be explained as more and more oxygen atoms trying to occupy the interstitial sites causing degradation in crystallinity of the film. figure 5: xrd pattern of post annealed (a) zno and (b) zto thin films at different temperatures ranges from 600-800oc for 60 min. figure 6 (a, b) shows the raman spectra of zno and zto thin films to understand the behavior of vibrational and rotational modes by varying the post growth annealing temperature from 600oc to 800oc. for both spectrums two major peaks at 437 cm-1 and 521cm-1 are present, which are related to the eg mode of zno and translational optical phonon mode of single crystal silicon respectively (montenegro et al., 2013; sahu, 2013). we have also observed a small peak at 302cm-1 related to double acoustic phonon mode of si and a peak at 458cm-1 is related to δ mode si-o (ferreira, santos, bonacin, passos, & pocrifka, 2015; tyschenko, volodin, & popov, 2019).the peaks appear at 379 cm-1 and574 cm-1 are assigned as a1(to),a1(lo) modes while the peaks at 410 cm-1,and 585 cm-1are related to e1 (to) and e1 (lo) modes of pure zno (cuscó et al., 2007). on the other hand, a large hump around 328cm-1is related to 2 2 high low e e− non-polar modes of zno. the presence of 2 2 high low e e− mode is occurred due to vibration of zinc sublattice and the motion of oxygen atoms (horzum et al., 2019). furthermore, a very small distortion at 614cm-1 is present, which is attributed to combined optical and acoustic mode of zno. but in case of zto samples fig. 6 (b) the peaks around 235 cm-1, 478 cm-1 and 546 cm-1 appears, which can be assigned to eu (1)to,eg and a2u to mode of sno2while the peak at 662 cm-1 is related to asymmetric vibration of sn-o-sn (mereu, le donne, trabattoni, acciarri, & binetti, 2015). the presence of sn elements in raman spectra further clarified our argument of the formation of zto. u. rehman, k. mahmood, a. ali, s. ikram 83 figure 6: raman spectrum of post annealed (a) zno and (b) zto thin films at different temperatures ranges from 600-800oc for 60 min. figure 7 depicts the sem images of as grown and annealed zto samples grown by thermal evaporation. sem image of as grown sample demonstrated the nano-structure morphology of sample but such nanostructures were disappeared when sample annealed at different temperatures. the disappearance of such structures is due to the incorporation of metallic ions into the grown films due to oxidation. figure 7: (a) (b) (c) (d) sem images of as grown and annealed zto samples journal of materials and physical sciences 1(2), 2020 84 4. conclusion in this research work, we have compared the post growth annealing effect on the thermoelectric properties of zno and zto thin films grown on si substrate and explore its potential for thermoelectric power generation applications. xrd data confirm the formation of hexagonal structure for both samples while the raman spectroscopy measurements verified the presence of sn elements in the zto samples. the temperature dependent seebeck and hall measurements were performed to understand the behavior of seebeck coefficient with post growth annealing and measurement temperature. it is found that the zto sample shows better thermoelectric properties as compared to zno sample. references abed, c., ali, m. b., addad, a., & elhouichet, h. 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august 20, 2021 revised: october 18, 2021 accepted: december 29, 2021 available online: december 31, 2021 the spinel oxides are one of the prime candidates for their use in thermoelectric and optoelectronic applications. this particular article mainly deals with the thermodynamic and mechanical stabilities of spinel sulfides confirmed by formation energy and born-mechanical stability criteria. the ductile behavior is achieved through poisson’s and pugh's ratios. the indirect band gaps of 1.9 ev, 1.7 ev and direct band gap of 1.3 ev for znin2s4, cdin2s4 and hgin2s4 spinel sulfides, respectively, are estimated by employing modified beckejohnson (mbj) potential in the wien2k computational program. the calculated optical characteristics such as dielectric coefficient, refractive index, absorption, reflection, energy loss coefficient and other related parametric quantities are explored to observe optoelectronic applications from uv to visible energy range as we move from zn to hg. moreover, the ratios of thermal conductivity to electrical conductivity, seebeck coefficient along with the figure of merits (zt) are discussed to acknowledge the thermoelectric behavior of all three materials. the high values of zt 0.84/0.74/0.79 are observed for zn/cd/hgin2s4 spinel sulfides which ensure their prospective use in thermal energy conversion devices, especially in thermoelectric generators. keywords: density functional theory electrical conductivity direct band gap semiconductor optoelectronic thermal electric efficiency © 2021 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: qmmustafa@iau.edu.sa 1. introduction the chemical formula of spinals is ab2x4 (where a and b are most likely divalent and trivalent metallic cations, respectively), and x is an anion that forms tetrahedrons and octahedrons around a and b ions, respectively (bragg, 1915; nishikawa, 1915). the large variety of verified synthesis techniques for the fabrication of spinels made it feasible to tune their surface features and lattice parameters (cheng et al., 2011; radaelli et al., 2002), consequently, fluctuating valence states of individual atoms and their relevant compositions have demonstrated robust impact upon physical characteristics of material (cho, lee, lee, hong, & cho, 2011; kaczmarczyk et al., 2016; marco et al., 2001; sonoyama, kawamura, yamada, & kanno, 2006; zhao, yan, chen, & chen, 2017). in spite of the fact that transparent conducting materials (tcm) have been proved to be valuable for diverse commercial optical applications (brunin, ricci, ha, rignanese, & hautier, 2019), but still, traditional transparent conducting oxides (tcos) shows complex characteristics because of the microstructures’ complexity (ginley & bright, 2000). that’s why a large part of material research community is still bus to find more efficient methods and advanced transparent conducting materials for their limitless applications in commercial optoelectronic devices. in recent years, spinels ab2x4 have attracted many researchers to study the physical properties (kefeni & mamba, 2020; narang & pubby, 2021; singh yadav et al., 2020; tsurkan, krug von nidda, deisenhofer, lunkenheimer, & loidl, 2021). https://journals.internationalrasd.org/index.php/jmps mailto:qmmustafa@iau.edu.sa journal of materials and physical sciences 2(2), 2021 70 a plethora of research reports is present related to the investigation of the physical properties of ab2s4. in 1969, znin2s4 was synthesized by range et al. the stability of cubic znin2s4 spinal was ensured, even after a period of one year, no transformation from cubic to any other phase was admitted by znin2s4 at room temperature and atmospheric pressure even after a period of one year (sriram et al., 1998). the reflectivity spectra of ab2s4 (a=zn, cd and b=in, ga) were studied for a wide energy range of 1-8ev under the action of unpolarized light at room temperature (turowski, kisiel, & giriat, 1984). s. k. batabyal et al. used the one-pot method to synthesize in2s3, znin2s4, and cdin2s4. afterward, they used x-ray powder diffraction (xrpd), transmission and scanning electron microscopies (tem & sem), selected area electron diffraction (saed) patterns, and energydispersive x-ray analysis (edx) for the characterization purposes of nano-crystals (batabyal, lu, & vittal, 2016). the effect of change in temperature on the electronic and optical properties of hgin2s4, has been calculated for the temperature interval of 10-300 k (syrbu, tiron, & zalamai, 2019). the ab-initio calculations of structural parameters, electronic properties, and transport properties were conducted by employing gga along with soc (spin-orbital coupling) for hgin2s4 and znin2s4 by using fp-lapw+lo method (kotbi, hartiti, fadili, ridah, & thevenin, 2019). the photoluminescence of mgin2s4 and hgin2s4 have revealed that donor-acceptor transmissions are dominant in the strong emission bands, which can also be observed in other members of this family (fortin, fafard, anedda, ledda, & charlebois, 1991). the known physical characteristics highlighted that xin2s4 (x=zn, cd, and hg) can be used in various devices for commercial as well as domestic use such as; light-emitting diodes (led), solar cells, photocatalysis, photosensors, charge storage devices, thermoelectricity, photoconductors (chen et al., 2016; ling et al., 2017; wang et al., 2021; zhang et al., 2022). although, multiple reports are accessible related to the study of znin2s4, cdin2s4 and hgin2s4 by varying x = zn, cd, hg. but, as per our best knowledge, no comprehensive report is present related to the physical properties, especially the thermodynamic and detailed optical response of xin2s4 (x = zn, cd, hg). in this report, we present optoelectronic and thermoelectric properties of xin2s4 (x = zn, cd, hg) by using mbj potential with the help of density functional theory-based calculations. 2. method of calculations this work includes in-depth study of band structure, optical properties, and thermoelectric performances of xin2s4 (x = zn, cd, hg) spinel sulfides that have been studied by using wien2k computational code (peter blaha, schwarz, madsen, kvasnicka, & luitz, 2001). in order to accurately calculate the hamiltonian, wien2k is built on fp-lapw method (p blaha & schwarz, 1987) supported by various potentials and approximations. the kohn-sham scheme along with pbe-gga approximation was utilized to compute structural parameters of ground state, which was initially followed by the murnaghan equation of state. since pbe-gga accurately estimates the ground-state parameters but underestimates electronic band structures. the electronic band structures are calculated by using mbj potential (koller, tran, & blaha, 2011; tran & blaha, 2009) to establish exact exchange and correlation with the help of following mathematical equation: 𝑉𝑥,𝜎 mbj(𝑟) = cv𝑥,𝜎 br (𝑟) + (3𝑐 − 2) 1 𝜋 √5 12 √2𝑡𝜎(𝑟) 𝜌𝜎(𝑟) (1) where 𝜌𝜎(𝑟) is density of states, 𝑉𝑥,𝜎 br(𝑟) is becke-roussel (br) potential, and c is charge convergence. the calculations for optical and thermoelectric characteristics of xin2s4 (x = zn, cd, hg) were followed by the electronic structures calculated with the help of mbj potential. kramer kroning relation (wooten, 2013) is used to extract the optical properties in wien2k code. while the thermoelectric properties are predicted by mean of transport coefficient in boltztrap code (madsen & singh, 2006; scheidemantel, ambrosch-draxl, thonhauser, badding, & sofo, 2003). the transport distribution functions were used to obtain the seebeck coefficient and thermoelectric conductivity as: 𝜎αβ(𝛼,𝜇) = 1 𝛺 ∫𝜎αβ ( )[− 𝜕𝑓0(𝑇,𝜀,𝜇) 𝜕𝜀 ]𝑑 (2) jameelah alzahrani, samah al-qaisi, q. mahmood, t. ghrib 71 𝑆αβ(𝑇,𝜇) = 1 et𝛺𝜎αβ(𝑇,𝜇) ∫𝜎αβ ( )( − 𝜇)[− 𝜕𝑓0(𝑇,𝜀,𝜇) 𝜕𝜀 ]𝑑 (3) where μ, ω, and ƒ0 shows the chemical potential, unit cell volume, and fermi-dirac distribution function respectively. in terms of boltztrap code, the relaxation time is 10−14 s. the rigid band approximation is used for evaluating the properties relative to the fermi energy (ryu & oh, 2016). moreover, the product of muffin-tin radius (rmt) and reciprocal lattice wave vector is 8. the maximum angular momentum ɩmax is 10. gmax is set to 16 (ry)1/2. the k-point grid is set to 10×10×10 along with 1000 k-points, after analyzing various k-mesh orders. 35 monk horst-pack k-points have been engaged for the charge/energy convergence test fixed at 0.00001 ry, after which all three cases have shown constant energy that shows fully converged structure. 3. results and discussion 3.1. thermodynamic and mechanical stability spinel sulfides xin2s4 (x = zn, cd, hg) are optimized in cubic phase by using pbegga approximation and plotted in fig.2. the atomic coordinates of x, in and s are (1/8, 1/8, 1/8), (1/2, 1/2, 1/2) and (1/4, 1/4, 1/4) accompanied by 227-fd3m space group. the inter-atomic strain forces are condensed up to 0.0001 gpa to achieve more stabilized structures. the lattice constants and bulk modulus are evaluated by applying murnaghan equation of state, summarized in table 1. computed lattice parameters improve from znin2s4 to hgin2s4, as well as, decay in bulk modulus have been witnessed due to varying ionic size from zn to hg. by using the following expression thermodynamic stability is ensured by analyzing enthalpy of formation (mahmood et al., 2019): 𝛥𝐻𝑓 = 𝐸𝑇𝑜𝑡𝑎𝑙(𝑋𝑙𝐼𝑛𝑚𝑆𝑛) − 𝑙𝐸𝑋 − 𝑚𝐸𝐼𝑛 − 𝑛𝐸𝑆 (4) here, 𝐸𝑇𝑜𝑡𝑎𝑙(𝑋𝑙𝐼𝑛𝑚𝑆𝑛) expresses spinel’s total energy. the bulk form energies for x (zn, cd, hg), in and s are denoted by 𝐸𝑋, 𝐸𝐼𝑛 and 𝐸𝑆, respectively. in all three cases the value of enthalpy is negative which divulge thermodynamically stable of considered spinal sulfides in cubic phases. noticeable improvements have been witnessed in the enthalpy of formation by replacement of x-cations from zn to hg, which portray higher stability due to tetrahedral and octahedral positions that turn out to be welcoming to the cations. figure 1: computed (a) crystal structure, (b) bond lengths, and (c) polyhedral of xin2s4 (x = zn, cd, hg) journal of materials and physical sciences 2(2), 2021 72 figure 2: optimized energy versus volume plots (a) znin2s4, (b) cdin2s4, and (c) hgin2s4 3.2. electronic properties in order to understand the electronic behavior of considered materials, the electronic band gap have been calculated by applying two well-known approximations (pbe-gga functional and mbj potential). the problem with pbe-gga approximation is that it underestimates the electronic band structure which can be resolved by using mbj potential which improves electronic band gap as compared to the computed band gap with the help of pbegga. the indirect bandgap of 1.9ev, 1.7ev and direct bandgap of 1.3ev have been visualized for znin2s4, cdin2s4 and hgin2s4, respectively as shown in fig.3. the decrease in bandgap with the increase in atomic radii has been observed, which ensures that electronic band gap of spinel sulfides is tunable within ultraviolet and visible energy range, which further points out to the prospect of altering the optical characteristics for range of optoelectronic devices. figure 3: the band structures of (a) znin2s4, (b) cdin2s4, and (c) hgin2s4 jameelah alzahrani, samah al-qaisi, q. mahmood, t. ghrib 73 3.3. optical properties optical features are elaborated through interaction of light with matter, during which electrons absorb light and display interand intra-band electronic transitions. for optical applications purposes, the inter-band transitions are relatively more appropriate as compared to the intra-band transitions which occur within bands. moreover, band gap of any compound has its own importance in optical behavior of any material due to the energy region having higher rate of absorption and exposure of the absorption edge (fox, 2002; khan, kashyap, solanki, nautiyal, & auluck, 1993; ramay, hassan, mahmood, & mahmood, 2017; rashid et al., 2019; zerarga, bouhemadou, khenata, & bin-omran, 2011). several optical constraints calculated for all three materials are shown in fig. 4(a-h). the complex dielectric constant ε(ω) = re ε(ω) +im ε(ω) is calculated to examine light polarization, absorption, and dispersion of incident light. the real part (re ε(ω)) and imaginary (im ε(ω)) parts are linked together via kramer-krong relation (horsley, artoni, & la rocca, 2015): 1(𝜔) = 1 + 2 𝜋 𝑃 ∫ 𝜔′𝜀2(𝜔 ′) 𝜔′ 2 −𝜔2 𝑑𝜔′ ∞ 0 (5) 2(𝜔) = 𝑒2ℎ′ 𝜋𝑚2𝜔2 ∑ ∫ |𝑀𝑐𝑣(𝑘)| 2𝛿[𝜔𝑐𝑣(𝑘) − 𝜔]𝑑 3𝑘 ∞ 𝐵𝑍𝑣,𝑐 (6) here p is the principal integral. the plots for re ε(ω) are given in fig. 4a. the static value of re ε(ω) and calculated band gaps are in agreement with the penn's model; re ε(0) ≈1+ (ħωp/eg)2, where ħ is the planck constant and ωp is the frequency of incident photons (penn, 1962; yazdanbakhsh, khosravi, goharshadi, & youssefi, 2010). the maximum values of re ε(ω) are achieved at 4.0 ev, 3.8 ev and 3.6 ev, which have shown huge variation with more increase in energy. the small humps in the energy range 5-6 ev are result of electronic transitions from occupied to unoccupied states. these values agree with stated band structures displayed in fig. 3. the imaginary dielectric coefficient is shown in fig. 4b which describes the optical absorption of the considered materials. the absorption edge after which the absorption of incident photons starts to increase can be approximated with the help of the band gap. the energy of absorption edge for examined im ε(ω) graph agrees with relevant band gap as shown in fig. 3. the intense peaks appeared at 4.3 ev, 4.1 ev, and 3.9 ev, for znin2s4, cdin2s4 and hgin2s4, respectively. therefore, maximum absorption is witnessed in uv region, that ensures their possible applicability in sterilization of surgical equipment and optoelectronics devices especially made to be used in ultraviolet region. the refractive index n (ω), extinction coefficient k (ω) and re ε(ω) are interrelated with each other, as stated in the equation: 𝑛2 − 𝑘2 = re (𝜔). the dimensionless n (ω) determine variation in the speed of light in particular material as compared to speed of light in the air and spreads wavelengths of incident light into its constituent colors, like re ε(ω). the refractive index of transparent medium is somewhere in between 1 to 3 for visible light. thus, the refractive indexes of these three spinels are suitable for numerous optoelectronic applications. the sharp peaks of refractive indices appear at 4.0 ev, 3.8 ev, and 3.6 ev, for znin2s4, cdin2s4, and hgin2s4, respectively, as displayed in fig. 4c. the displayed refractive index n (0) at zero frequency and re ε (0) at zero frequency agrees according to the equation stated earlier, which verifies the accuracy of the computed results. the extinction coefficient and refractive index are related to the imaginary part of the dielectric coefficient by the expression; 2nk (ω) = im ε (0) and demonstrate similarity in the behavior of extinction coefficient and im ε(ω), as illustrated in fig. 4d. the absorption coefficient is calculated to visualize the absorptive nature of considered materials under the influence of incident photons passing through the particular materials is plotted in fig. 4e. from energy value 0 ev to 1.9 ev, 1.7 ev, and 1.3 ev, for znin2s4, cdin2s4, and hgin2s4, respectively, negligible absorption can be seen from fig. 4e, which signify the threshold limit and is comparable to the band gaps observed from the measured band structures. the intensified rate of absorption of light occurs in uv-region as manifested earlier from im ε(ω) and k (ω). journal of materials and physical sciences 2(2), 2021 74 figure 4: computed (a) ε1 (ω), (b) ε2 (ω), (c) n(ω), (d) k (ω), (e) α (ω), (f) σ(ω), (g) r (ω), and (h) l (ω) for xin2s4 (x = zn, cd, and hg) where lines of black, red and green color plots the information of znin2s4, cdin2s4 and hgin2s4, respectively under the influence of light, the electrons in the valence band jumps to conduction band and generates photocurrent after sufficient energy which is required to cross the band gap energy, for that reason, optical conductivity σ (ω) of material increases with increase in the energy of incident light after the defined band gap. the computed σ (ω) are plotted in fig. 4f, which confirms the parallel trends as seen from the absorption coefficient. the irregular behavior of the calculated reflectivity r (ω) for xin2s4 (x=zn, cd, and hg) is exposed in fig. 4g. it shows high value but less than 0.4 in the energy range 3.5 ev to 4.5 ev. the energy loss l (ω) is illustrated in fig. 4h, from which it is crystal clear that the energy loss in the visible region is very small, leading to the fact that these materials can be used for potential uses in optical device fabrication applicable in visible energy region. jameelah alzahrani, samah al-qaisi, q. mahmood, t. ghrib 75 4. conclusion this manuscript contains the detailed 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(2017). spinels: controlled preparation, oxygen reduction/evolution reaction application, and beyond. chemical reviews, 117(15), 10121-10211. doi:10.1021/acs.chemrev.7b00051 https://doi.org/10.1016/j.jmst.2020.09.045 https://doi.org/10.1016/j.jhazmat.2010.08.092 https://doi.org/10.1016/j.solidstatesciences.2011.06.016 https://doi.org/10.1016/j.gee.2020.12.015 https://doi.org/10.52131/jmps.2022.0301.0024 29 journal of materials and physical sciences volume 3, number 1, 2022, pages 29 37 journal homepage: https://journals.internationalrasd.org/index.php/jmps investigation of morphological, elemental, structural, and optical properties of fe-doped tio2 nanoparticles muhammad irfan ahmad1, hafiz muhammad asif javed1*, asad ali1, zaheer ul hassan1, m. afzaal2, muhammad arif3, shahid hussain4 1 nanomaterials and solar energy research laboratory, department of physics, university of agriculture faisalabad, 38000, faisalabad, pakistan 2 department of physics, riphah international university faisalabad campus, pakistan 3 nfc institute of engineering and fertilizer research, faisalabad, pakistan 4 school of materials science and engineering, jiangsu university, 212013, zhenjiang, china article info abstract article history: received: march 24, 2022 revised: may 29, 2022 accepted: june 29, 2022 available online: june 30, 2022 in this research, fe-doped tio2 nanoparticles were synthesized by sol-gel technique followed by annealing at 450 oc in a vacuum. the effects of fe-doping on the morphological, elemental, structural and optical properties of tio2 nanoparticles have been investigated. xrd analysis was performed to examine the structural properties of synthesized pure tio2 nanoparticles and fe-doped tio2 nanoparticles. surface analysis was done using scanning electron microscopy. optical properties were determined using uv/vis spectroscopy. morphological analysis revealed that tio2 nanoparticles have a spherical shape. edx analysis confirmed the elemental composition of fe-doped tio2 nanoparticles. xrd patterns showed that diffraction peaks can be attributed to tio2 with the anatase phase. keywords: tio2 nanoparticles fe-doped tio2 nanoparticles morphological analysis elemental analysis structural analysis uv/vis spectra analysis © 2022 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: m.asif.javed@uaf.edu.pk 1. introduction nanoparticles are tiny objects that play a vital role in many applications due to their characteristics and functionality. nanoparticles should have been considered substances with a certain degree of physical state in addition to solid, liquid, and gaseous plasma states due to their unique nature(larumbe, monge, & gómez-polo, 2015). the synthesis of tio2 nanoparticles can be done in various ways, but the sol-gel approach is very convenient. it is a more widespread and general approach for synthesising tio2 nanoparticles(yu et al., 2006). when the interactions connecting two particles are sufficiently repulsive, and the su faces supporting forces prevent agglomeration and coagulation, the solution becomes stable. when another addition removes the charge on the particle, the system collapses (flocculation), resulting in gel formation(valero-romero et al., 2019). this procedure involves passing the system through a colloidal form of a liquid sol, which is then transformed into a sol-gel phase. sol is commonly made with an organic metal complex such as a metal alkoxide/inorganic metal salt(z. li, shen, he, & zu, 2008). there are two types of sol-gel techniques; the first is an aqueous technique that results in an inorganic metal salt. while the other is an alcohol-based process with metal alkoxide as the first precursor. titanium oxide (tio2) is a naturally occurring mineral(sood, umar, mehta, & kansal, 2015). titanium oxide is a semiconductor material having band energy equal to or higher than bandgap energy and photocatalytic activity when exposed to sunshine. titanium dioxide is not found in pure form in the earth but comes from white oxen or limonite ore. titanium dioxide crystallizes after passing through the amorphous state(kim, hong, kim, song, & lee, 2004). titanium dioxide crystallizes after passing https://journals.internationalrasd.org/index.php/jmps mailto:m.asif.javed@uaf.edu.pk journal of materials and physical sciences 3(1), 2022 30 through the amorphous state. titanium dioxide is non-poisonous and an incomplete acidic oxide that is synthetically stable. titanium dioxide is non-poisonous and has a stable synthetic structure. at room temperature, there was no response to various compounds(nasralla et al., 2013). titanium dioxide is a fragmentary acidic oxide. the crystalline arrangement of the titanium nanoparticles largely depends on the preparation procedure. the size of titanium dioxide nanoparticles is lowered, and the number of positioned atoms increases, improving catalytic activity even more. plastics, coatings, uvresistant materials, links, and chemical fibers all contain these nanoparticles. 2. experimental section 2.1. synthesis of fe-doped tio2 nanoparticles tio2 photocatalysts were prepared using a modified sol-gel technique. solution a was created by pouring 20 ml of ttip into 80 ml of 100% ethanol. in addition, 2 ml distilled water and 2 ml h2so4 were blended in 20 ml 100% ethanol to make solution b. solution b was added dropwise to solution a while vigorously stirred. the gel was created by stirring the solution at room temperature(ali et al., 2017). the gel was aged at 80℃ for 24 hours at room temperature, dried in an oven, and ground to powder. the calcination is carried furnace at 400℃. for an indication of the nanoparticles, the fto substrates have been first cleaned completely with the help of ethanol and then dried earlier before deposition(dholam, patel, adami, & miotello, 2009). these substrates were dunked in the viscous pure “tio2-sol” of identified consistency after drying at the room-temperature. following such a strategy, nanoparticles have been kept by antecedent-sol of the various viscosities to contemplating the connection between the consistency of forerunner sol and the thickness of a film. a thin film of titanium (tio2) framed upon the fto substrate was firstly dried in the air at room-temperature took after drying at the temperature of 80˚c for 3 hours in the oven(einert, hartmann, smarsly, & brezesinski, 2021). the film framed is additionally warmed at the temperature of 400˚c for only 1 hour in the furnace in the presence of air. this technique makes the thin film on substrates look like a glass plate. a thin film of titanium dioxide was shaped onto the fto substrate(zheng et al., 2022). also, after warming treatment, these were used for the photocatalytic response. even though we have arranged films on different types of substrates such as treated steel, aluminium, or clay plates, the films kept on the glass substrates have been contemplated specifically for the auxiliary and photocatalytic conduct for accommodation(kanjana, maiaugree, poolcharuansin, & laokul, 2021). hina powder was mixed with ethanol and stirred on the stirrer for one hour without providing heat to obtain the hina powder solution. for this purpose, the weight of hina powder was 5gm, and ethanol was 100ml(kanjana et al., 2021). fto was cleaned with ethanol and, using a voltmeter, checked its conducting side. by using tapes, fto was fixed on the table. a paste of tio2 was deposited on its conducting side, which was dried for 1 hour and dipped into the hina powder solution for some time, so that layer of dye (hina powder) is deposited onto the photo anode for light harvesting(na et al., 2021). a photoanode of tio2 was prepared. we cleaned fto with ethanol and checked its conducting side using a voltmeter. the fto was fixed on the table by using tapes. a paste of the composite of fe doped tio2 was deposited on its conducting side, which was dried for 1 hour(baruah et al., 2021). 2.2. characterizations tio2 nanoparticles have been prepared by the method of sol-gel. the precursor used in this method was titanium tetra-isopropoxide (ttip). starting precursor for this method was titanium tetra-isopropoxide (ttip). water and ethanol acted as a solvent in this method, and h2so4 was used as an acidic catalyst, making the reaction much faster than without a catalyst. the prepared titanium dioxide nanoparticles sample was examined using different techniques. the diffraction method characterizes the nanostructure of synthetic titania nanoparticles. for this purpose, the technique which was used named as powder xrd method. to determine the structure of crystalline solids, this diffraction method xrd is widely used(zheng et al., 2022). this method can quickly obtain diffraction data, and this powder method can be applied to all crystalline materials. each product has unique diffraction data, and powder can be used to easily identify any substance. samples were characterized by x-ray diffraction (xrd). the crystal size was determined by a formula m. irfan ahmad, hafiz m. asif javed, asad ali, zaheer ul hassan, m. afzaal, m. arif, shahid hussain 31 known as scherer’s formula. reduced temperature and crystalline size decrease. sem observed images of prepared samples, and edx determined elemental composition and ratio. 3. results and discussion 3.1. morphological analysis sem analysis of the prepared sample of fe-doped tio2 nanoparticles samples. a scanning electron microscope (sem) is an electron microscope that makes images of a sample by scanning the surface with a focused beam of electrons. and the process of making the sample images is discussed as the electrons interact with atoms in the sample, producing various signals containing information about the surface topography and composition of the sample. the electron beam is scanned in a raster scan pattern. the beam's position is combined with the detected signal to produce an image. sem can achieve resolution better than 1 nanometer. samples are observed in high vacuum in conventional sem, in low vacuum or wet conditions in variable pressure or environmental sem, and at a wide range of cryogenic or elevated temperatures with specialized instruments. the most common mode of sem is detecting secondary electrons emitted by atoms when an electron beam strikes them and excites them. a special detector detects secondary electrons emitted by the electron beam from the sample atoms. the sem micrographs of the fe-doped tio2 nanoparticles were formed at 400°c for 4h(sukhadeve et al., 2022). in general, all the fe-doped tio2 nanoparticles show nano size and have a spherical shape in powder particles. the pure tio2 particles range from 1−3μm, and doped particles show about 200 to 500mm in size. a close considers these powders. micrographs reveal that the degree of assembling initially decreased with the doping of fe into tio2. after that, it gradually increased with the further increase of fe content in tio2 (xia et al., 2022). sem revealed the external morphology, chemical composition, crystalline structure, and orientation of materials making up the sample. the morphology of the fe-doped tio2 nanoparticles is shown in the figures. it presents clear evidence that uniform-sized particles are spherical in shape. the sem of the iron-doped tio2 samples reveals that the crystals are nanometer-sized. therefore, the growth of nanophase crystalline tio2 particles was accelerated at higher calcined temperatures(begna, gurmesa, zhang, & geffe, 2022). all samples show uniform morphology in the form of tio2 nanoclusters. it has been observed that the tio2 nanoparticles annealed at 400ºc almost reveal that the primary particles are quite uniform in size, quite clean, and roughly spherical. the agglomerates are fused to form comparatively smaller irregular grains giving rise to highly porous materials which enhance the photovoltaic performance(song et al., 2022). the fe-doped tio2 nanoparticles have a larger grain size. it exhibits lesser receptivity and higher transparency, which are important for tco applications. figure 1 shows the sem images of fe-doped tio2 nanoparticles at different magnification widths and views fields 5.49mm, 171µm, 5.46mm, 65µm, 5.47mm, 33.3µm, 5.47mm, 16.5µm, 5.49mm, 3.29µm and 5.48mm, 1.67µm respectively(zhao, ren, huang, chen, & bian, 2022). in picture e, at the magnification of 1µm, the radius of doped nanoparticles at different points is given at c1 70.38nm, c2 66.15nm, and c3 74.91nm. in the last picture, the magnification of the 500nm radius of doped nanoparticles is like at c1 28.52nm, c2 24.79nm, and c3 28.84nm. 3.2. elemental analysis to find out the elemental composition of prepared samples, edx is used to analyze the samples. for the elemental analysis or chemical characterization of samples. an analytical technique is called energy-dispersive x-ray spectroscopy, energy dispersive x-ray analysis (edxa), or energy dispersive x-ray microanalysis (edxma) is useful for characterization. the mechanism of this technique is an interaction of x-ray excitation with a sample. a high-energy beam of charged particles such as electrons or protons, or a beam of x-rays, is focused on the samples to stimulate the emission of characteristic x-rays from journal of materials and physical sciences 3(1), 2022 32 samples. an atom within the sample, when at rest, contains ground state electrons in discrete energy levels or electron shells bound to the nucleus(wang et al., 2022). the incident beam will create the electron-hole pair by exciting an electron from an inner shell. when an electron-hole pair is created, the outer higher-energy shell fills this hole; when an electron of a higher energy level fills this hole, it will release the energy to come down, which will be in the form of an x-ray. this energy released by the electrons and the number of x-rays emitted from a sample will be measured by an instrument called an energydispersive spectrometer (jia et al., 2022). figure 1: sem images of fe-doped tio2 nanoparticles with different magnification eds allows the elemental composition of the samples to be measured as the energies of the x-rays are characteristics of the difference in energy between the two shells and the atomic structure of the emitting element. after that, the weight percentage of the elements present in the samples can observe. this percentage will be determined by the m. irfan ahmad, hafiz m. asif javed, asad ali, zaheer ul hassan, m. afzaal, m. arif, shahid hussain 33 technique named energy dispersive x-ray spectrometer. using this technique, we will know the weight percentage of major and minor elements present in the samples. in the energy dispersive x-ray spectrometer, an accelerating voltage is 20kev(dharmale, chaudhury, & pandey, 2022). the edx analysis of fe-doped tio2 nanoparticles calcined at 400˚c is shown below. the atomic and the weight percentage of minor and major elements are shown in the tables below. from the given tables, we can say that elements are present in the samples, such as ti, o & doped element, which is iron in this case present the samples. doped tio2 shows the sample's chemical composition of ti, o, and fe in fe. there are some minor impurity peaks in the pure sample, which were observed in the edx spectra. it confirms that the prepared samples have some impurities like oxygen and sulphur. in figure 4.3, there are two different pictures. one is an sem image at 20µm, and the other shows elemental composition in the sample. from this, it can see. there are various elements like oxygen, sulphur, and ti. ti is the element present in a small amount in the sample, as shown in spectrum 1. there are some other elements present in the sample which show small peaks in spectrum 1. at 0kv and 4kv, peaks show ti present in a small amount. shows the elemental composition with weight and atomic percentage. from the table, we can say that in the sample, there is ti which has a 58.11 weight percentage, oxygen has 37.18, and sulphur has 4.71 %(w. li et al., 2022). from this, we can see. there are different elements like oxygen, sulphur, and ti. the most amount of fe is present in spectrum 2. from the figure given below, we can say that there are elements such as ti, s, o, and fe in the spectrum. at 6.5kev, there is fe present in a small amount. it shows that this sample contains the doped element in most amounts. from the given table, we can say that there is a much more weight percentage of fe than other elements. from the table, fe has 77.13, oxygen 12.19, and ti has 4.31 weight %(yuzer et al., 2022). figure 2: edx of fe-doped tio2 nanoparticles 3.3. structural analysis in this experiment, the physical grinding method is used to get the nanoparticle size of tio2 powder. the tio2 quantity in powder form is obtained at 8gm. after that, quantity in the mortar and grind, powder form with the help of pestle for 15 minutes to prepare nanoparticles. we turn off fan to avoid impurities like air or dust. after we got nanoparticles size powder, we put this with the help of a spatula into china dishes and then put these china dishes into the furnace just for calcination. after that, we send our sample to islamabad for xrd analysis. the xrd spectra or technique gives information about the structure, crystallite size, and lattice planes or strain. the broad peaks indicate either particles of a very small crystalline size or semi-crystalline particles. the average crystalline size (the symbol used for crystalline size is d) of titanium dioxide and fe-doped titanium dioxide nanoparticles was calculated using debye scherer’s formula. for example, d =, where β is the full width at the half-maximum intensity (fwhm), θ is the diffraction angle, and λ is the wavelength of the x-rays, which is 0.1549 nm or 1.549å(yuzer et al., 2022). journal of materials and physical sciences 3(1), 2022 34 the calculated crystallite average radius for titanium dioxide and fe-doped titanium dioxide was 22 nm and 28 nm, respectively. at some points of the sample where fe is in very small content(bhatti, parikh, & shah, 2022), the xrd observed no crystalline phase. these results show that the doping of fe possesses uniform distribution and forms a stable solid solution within titanium dioxide. the diffraction pattern confirmed that the materials prepared in the lab are in the form of small particles because the peaks are broad. the xrd patterns of fe-doped tio2 samples are shown in the figure. from the figures given below, it is clear that up to some peaks of the samples of doped tio2 nanoparticles show no structural difference in x-ray spectra. xrd peaks of all the samples where fe content is very low except where fe content is most tio2 corresponding to the anatase phase. the intensity of the main anatase peak (101) at 2θ = 25.27 decreased considerably compared to the pure sample. the peaks at 2θ, i.e., 25.24, 39.11, 47.93, and 54.34 degrees related to lattice planes (101), (200), (111), (210), and (002), which are compatible with rutile phase (jcpds 21-1276)(abraham & devi, 2022). from this, we can see clearly that up to the small content of fe, the tio2 powders exhibit an anatase phase, and a clear phase transformation from the anatase to rutile occurs as doping of fe increases. these graphs were made in the software named origin 8 pros. in the graphs of doped tio2 nanoparticles, we took on x-axis 2 theta in degree. on y-axis, we took intensity in a.u. on x-axis, we start from 20 degrees and end at 60 degrees by a difference of 10 degrees. from the first graph below, the first peak is shown (101), which is the main peak. and in the second graph, we also took on x-axis 2 theta in degree, and on y-axis, we took intensity in a.u. on x-axis, we start from 20 degrees and end at 60 degrees by a difference of 10 degrees. this first peak is also (101), which is the main peak but shows a difference compared to the peak of pure because it is a wide and small peak. the figure shows the xrd spectra of fe doped tio2 nanoparticles, respectively. 20 30 40 50 60 in te n si ty / a .u . 2 theta / degree fe / tio2( 1 0 1 ) (2 0 0 ) (1 1 1 ) (2 1 0 ) (0 0 2 ) figure 3: xrd spectra of fe-doped tio2 nanoparticles 3.4. uv/vis spectra analysis to observe the prepared samples technique is used named uv-visible spectroscopy. this technique measured the scattering and absorption of light. the light passes through a sample as the sample is in the form of nanoparticles. and these particles have unique optical properties like size, concentration, shape, agglomeration state, and reflective index. therefore, uv-visible is a valuable tool for characterizing, identifying, and studying nanoparticles. for studying uv-visible spectral, the prepared sample of doped tio2 nanoparticles lambda 35 model uv-visible spectrometer ranged from 300 to 900nm. absorption spectroscopy was used to find and explore prepared nanoparticles' optical properties, a powerful non-destructive technique. the uv-visible spectral studies of the fedoped tio2 nanoparticle are shown below. the doped tio2 nanoparticles were calcined at 500ºc(zhang, zhang, zhong, & ding, 2022). the visible light strongly exhibits photon absorption and produces high photocatalytic activity. these results concluded that the fedoped tio2 nanoparticles exhibit higher absorption than the pure sample. the absorption spectrum of fe-doped tio2 shows broader absorption in the entire visible region. it is a good condition for solar cell applications. the energy gaps of doped tio2 show high m. irfan ahmad, hafiz m. asif javed, asad ali, zaheer ul hassan, m. afzaal, m. arif, shahid hussain 35 absorption occurs mostly invisible region for doped tio2 nanoparticles. fe doped tio2 samples' absorption spectra exhibit strong and broad absorption. it is an excellent understanding of the band gap of the anatase phase. the lowest bandgap value of doped tio2 nanoparticles exhibits the rutile phase, and the size of the particle becomes bigger(sakfali, ben chaabene, akkari, & zina, 2022). we prepared the fe-doped tio2 nanoparticles sample in the lab and then observed their uv-visible spectrum. these are the uv-visible spectrum of prepared nanoparticles, which are given below in the form of a graph. 400 500 600 700 800 0.0 0.5 1.0 1.5 2.0 2.5 a b so r p ti o n / a .u . wavelength (nm) fe-tio2 figure 4: uv/vis spectrum of fe-doped tio2 nanoparticles acknowledgments this work was supported by the higher education commission (hec) of pakistan under grant # 9371/punjab/ nrpu/r&d/hec/2017. references abraham, c., & devi, l. g. 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(2022). construction of fe-doped tio2− x ultrathin nanosheets with rich oxygen vacancies for highly efficient oxidation of h2s. chemical engineering journal, 430, 132917. https://doi.org/10.52131/jmps.2021.0201.00015 45 journal of materials and physical sciences volume 2, number 1, 2021, pages 45 53 journal homepage: https://journals.internationalrasd.org/index.php/jmps characterization of zr-al substituted m-type barium hexaferrite synthesized by co-precipitation method humaira akhtar shahia1, muhammad shahzad shifa2*, zeshan mehboob1, muhammad hashim2, faseeh ur raheem2 1 department of physics, govt college university faisalabad, allama iqbal road, faisalabad, pakistan 2 institute of physics, the islamia university of bahawalpur, bahawalpur, pakistan article info abstract article history: received: april 19, 2020 revised: may 27, 2020 accepted: june 28, 2020 available online: june 30, 2020 structural properties of zr-al substituted m-type of barium hexaferrites, having compositions ba1-xzr0.5xal0.3fe11.7o19, (x= 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) are studied, which were synthesized by using co-precipitation method. these prepared samples are characterized by x-ray diffraction (xrd) to confirm hexaferrites structure. fourier transform infrared spectroscopy is used to make tetrahedral (higher frequency band) and octahedral (lower frequency band) clusters of metal oxides in hexaferrites and confirmed the formation of hexaferrites structure. (fesem) field emission scanning electron microscopy was used to give micrographs to show that grains are platelet like shaped, which agrees very well with hexaferrites structure. the particle morphology is observed to be porous and non-uniform. the grain size is decreased initially, and then increased with zirconium additions. scherer’s formula is applied to calculate particle size, which is observed to change in the range of 18.86 nm9.43 nm. the grains are bounded together due to interfacial surface tension forces. the optical properties are also studied by uv vis spectrometer to find the energy band gap, in the range of 2.09ev 5.15ev and absorbance peak having the range 237.9nm 252.13nm. this change in energy band gap and absorbance peak is due to the change in the grain size on the zirconium substitution. keywords: zr-al ferrite m-type barium ferrites co-precipitation method xrd ftir fesem uv-vis spectrometer © 2021 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: shahzad.shifa@gmail.com 1. introduction nano particles are being widely used in modern technology of our daily used appliances. nano particles are actually atoms/molecules bonded together having radius less than 100 nm. nano particles, called ferrites are ceramic compounds made up of oxides having iron as main component. ferrites may be soft or hard magnetic materials. they are extremely magnetic in nature. ferrites are classified into spinel ferrites, garnets, ortho ferrites and hexaferrites. among these ferrites, only hexagonal ferrites are hard ferrites and others are soft ferrites. we used hard ferrites in our research. hexagonal ferrites (mefe12o19) can be further divided into m-type (bafe12 o19) ,y-type (ba2me2fe12o22), w-type (bame2fe16o27), x-type (ba2me2fe28o46), z-type (ba3me2fe24o41) and u-type (ba4me2fe36o60) by (özgür, alivov, & morkoç, 2009; smit & wijn, 1959). m-type barium hexaferrites (bafe12o19) are the most important series of the hard ferrites which has a wide range of applications, such as in permanent magnets (litsardakis, manolakis, serletis, & efthimiadis, 2008), loud speakers, id cards etc. https://journals.internationalrasd.org/index.php/jmps mailto:shahzad.shifa@gmail.com journal of materials and physical sciences 2(1), 2021 46 these applications are due to their large coercivity (livingston, 1981), high saturation and magnetization and easier synthesis etc. these mtype barium hexaferrites are also used in magnetic recording applications due to their low manufacturing cost for industrial production and chemical stability (ahmed, okasha, & kershi, 2008; yamamoto, nagakura, & terada, 1990). they are widely used in magnetic sensors electrodes, entertainment applications, photo-catalytic activity, hyperthermia applications, pollution control and drug delivery applications (arruebo, fernández-pacheco, ibarra, & santamaría, 2007) etc. the improvement in structural and magnetic properties of these hard ferrites, e.g. corcivity, remanence, crystallite size etc. depend upon their method of synthesis and substitution of divalent or trivalent cations, particularly ba+2/fe+3 ions. (bsoul & mahmood, 2009; lee et al., 2010; sözeri, 2009). the large anisotropy is also reduced by substitution of fe+3 and/or ba+2 by other metal cations to make them most stable for magneto optical recording media due to their microwave absorption properties. the m-type hexaferrites consists of a unit cell with the lattice parameter a=5.88 å and c= 23.2 å. our research belongs to m-type barium hexaferrites (bafe12 o19) which depends upon the magnetic character (fe+3 ion) having magnetic moment 5 µb. each unit cell consists of 64 ions: 38 ions of oxygen, 24 ions fe (iron) and one me ion (me= ba2+, pb2+, sr2+ and la2+). ferric ions lie at 5 sites named as 2a, 2b, 4f1, 4f2 and 12k. here 2a, 4f2 and 12k are octahedral, 4f1 is tetrahedral and 2b with 5 surrounding oxygen atoms form trigonal bi pyramid. the oxygen atoms lie at 4e, 4f, 6h and 12k sites to form closed packed lattice. the me ions occupy the 2d sites. out of 12 fe+3 ions in a formula unit, 6 fe+3 lie at 12k sites and have spin up. 2, 2 ions lie at 4f1 and 4f2 sites with spin down while 1, 1 ion lies at 2a and 2b sites with spin up. so, out of 8 fe+3 ions, having spin up (parallel to c-axis), 4 fe+3 ions are cancelled out by fe+3 ions with spin down. the remaining 4 fe+3 ions, each with 5 unpaired electrons, give rise to 20µb magnetic moment per formula unit. the most commonly used and effectively methods to prepare these m-type barium hexaferrites are high energy ball milling method (ketov, yagodkin, lebed, chernopyatova, & khlopkov, 2006), sol-gel method (abbas et al., 2015), co-precipitation technique (jotania & patel, 2012), hydro thermal (ataie, harris, & ponton, 1995), and chemical mixing (dushaq et al., 2013) etc. among all these methods, co-precipitation technique is the simplest, most effective, cheap, direct and controllable method to prepare hexaferrites. our present research is about to characterize zr-al substituted m-type barium hexaferrites, having formula ba1xzr0.5x al0.3 fe11.7 o19, (x= 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) synthesized by co-precipitation method. the objective of present work is to study the variation in structural, optical and magnetic properties of zr-al substituted m-type barium hexaferrite with the addition of zirconium in place of barium, which was not investigated before this, as according to the best of our knowledge. 2. experimental procedure ba1-xzr0.5x al0.3 fe11.7 o19hexaferrites with (x= 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared by using co-precipitation method. the chemicals used were ba(no3)2 (barium nitrate), zrcl4 (zirconium chloride), fe(no3)3.9h2o(iron nitrate), al2(no3) (aluminum nitrate), naoh (sodium hydroxide). and diw (deionized water) (h2o) was also used to make the precursors. all the metal nitrates and chlorides with particular stoichiometric ratio (according the formula) were mixed in 1000 ml beakers containing de ionized water. the solutions were made by shaking and heating all the ingredients at about 50℃-60℃ at first, and then stirred magnetically on magnetic hot plates, to form homogenous solutions. the sodium hydroxide (naoh) solution was used to drop in the prepared solution, to get ph of about 10-12. after heating it further for 5-6 hours and then cooling, we got precipitates. we washed them with de-ionized water 5-6 times, to remove nitrates and chlorides contents. when the ph value reached to about 7, the solution was filtered with filter paper to separate the precipitates. these precipitates were dried in oven at 90℃ for 8 hours. the dried samples were ground and mixed by mortar and pestle, for about 30 minutes. then the samples were annealed in furnace at 950℃ for about 6 hours. after cooling them, these samples were again ground and mixed to make the fine powder. then these are ready to be used for various characterization techniques to study different properties. humaira akhtar shahia, muhammad shahzad shifa, zeshan mehboob, muhammad hashim, faseeh ur raheem 47 3. characterizations 3.1. xrd analysis the xrd patterns of all the sintered samples of ba1-xzr0.5x al0.3 fe11.7 o19, (x= 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) for the angles 30o56o are shown below in figure 1. all the peaks of xrd patterns were observed at angles of about 30o, 32o, 34o, 35o, 36o, 40o, 54o and 56o. these peaks were well indexed and were compared with jcpds file no. 033-1340 with space group p63/mmc (194). these peaks were indexed to the crystal planes of m-type hexaferrites i.e., (110), (112), (114), (200), (203), (205), (217) and (2011) respectively. (almessiere, slimani, el sayed, baykal, & ercan, 2019; gunanto, jobiliong, & adi, 2016; li, qiao, li, liu, & peng, 2013). the remaining small peaks are due to the impurities present in the raw material. the four more prominent peaks in the xrd pattern were selected to find various parameters, like crystallite size(d), x-ray density 𝜌(𝑥 − 𝑟𝑎𝑦) , inter planer spacing (d), lattice parameters(a) and (c) and cell volume (v) etc. by using the following formulas: 𝑑 = 𝜆 2𝑠𝑖𝑛𝛲 (1) d= 𝐾𝜆 𝛽(ℎ𝑘𝑙)𝐶𝑂𝑆𝛲 (2) 1 .d^2 = 4 3 ℎ^2+ℎ𝑘+𝑘^2 𝑎^2 + 𝑙^2 𝑐^2 (3) 𝜌(𝑥 − 𝑟𝑎𝑦) = 𝑍𝑀 𝑁𝐴𝑉 (4) 𝑉 = 0.8666𝑎2𝐶 (5) where 𝝺 is the x-ray wavelength which is equal to 1.5414å, k is the shape factor and its value is equal to 0.89 for hexagonal structure. 𝝦 is the bragg’ diffraction angle. 𝞫hkl is fwhm (full wave half maxima) of respective plain. na is avogadro’s number (6.02× 1023 g/mole). m is molecular weight and z is no. of molecules or formula units per unit cell of hexaferrites and is equal to 2. (m. a. almessier et al., 1982). ρ is the x-ray density. the density (ρ) of the hexaferrites must be about 5.4 gm/cm3 (ghzaiel, dhaoui, pasko, & mazaleyrat, 2016). m-type hexaferrites, the lattice parameter (a) and (c) must have the value of about 5.8 å and 23.2 å respectively. the ratio a/c for pure m-type ba hexaferrites must be equal to 3.935 (chawla, meena, kaur, mudsainiyan, & yusuf, 2015). the cell volume was found by using eq. (3.5) given above. average cell volume of pure hexaferrites must be about 690 å3 (ashraf, zhang, abbas, & murtaza, 2018). the average crystallite size d must be in the range 15 nm-60 nm (almessiere et al., 2019; gunanto et al., 2016; mahmood & bsoul, 2017; wang et al., 2016). in all the samples, the crystallite size is found in the range of 9.43 nm-18.86 nm, the average cell volume of all the samples is in the range of 539.77(å3) to 502.51(å3). table 1 samples’ crystallite size, interplanar spacing, cell volume, and density samples crystallite size (d) (nm) interplanar spacing (d) (å) cell volume (v) (å) density (ρ) g/cm3 baal 0.3 fe 11.7 o 19 x=0.0 15.64 2.38 539.77 6.786 ba 0.9 zr 0.05 al 0.3 fe 11.7 o 19 x=0.1 9.49 3.36 496.32 7.319 ba 0.8 zr 0.1 al 0.3 fe 11.7 o 19 x=0.2 9.43 2.36 519.43 6.935 ba 0.7 zr 0.15 al 0.3 fe 11.7 o 19 x=0.3 17 2.38 537.24 6.648 ba 0.6 zr 0.2 al 0.3 fe 11.7 o 19 x=0.4 18.86 2.38 533.99 6.631 ba 0.5 zr 0.25 al 0.3 fe 11.7 o 19 x=0.5 18.80 2.38 502.51 6.986 both of these results prove our samples to be m-type hexaferrites according to the literature mentioned above and also best for high density recording media (christy, rewatkar, & sawadh, 2017). the crystallite size (d) and the average cell volume (v) must decrease with the addition of zirconium (zr+4) in each sample, because zirconium is a nonmagnetic ion having ionic radius of 80 pm, while that of barium is 268 pm. so if barium is replaced by zirconium having smaller radius, the radius, crystallite size and hence the cell volume in our samples(ba1-xzr0.5x al0.3 fe11.7 o19, (x= 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) must decrease (christy et al., 2017). but we see that in first three samples, the crystallite size(d) decrease and then starts to increase. similarly the cell volume (v) decreases in first two journal of materials and physical sciences 2(1), 2021 48 samples, but decreases onwards. the reason may be due to the fact explained below; zirconium (zr+4) usually likes to occupy mostly 2b (bipyramidal sites) sites and a little 4f1 (tetrahedral sites) sites (jancarik et al., 2011). these sites are already occupied by iron (fe+3) ions. also as for barium in tetrahedral sites, zirconium (zr+4) ions are distributed probably between tetrahedral and octahedral sites and have no particular preference due to its do configuration (kanagesan, jesurani, velmurugan, prabu, & kalaivani, 2012). figure 1: xray diffraction peaks since the ionic radius of fe3+ is 69 pm. zirconium (having larger ionic radius as compared to iron (fe3+)) substitutes fe3+ at 4f1 site initially and then at 2b site afterwards, with the increasing zr concentration. so, for both of these sites, substitution of zirconium, cause the particle size (d) and cell volume (v) to increase. similarly the lattice parameter (a) and (c) of our samples are found in the range of 5.0 (å) to 5.26 (å) and 21.36 (å) to 20.8(å) respectively, which is in full agreement with the literature for m-type hexaferrites, stated above (gunanto et al., 2016). we can see in table 2 that lattice parameters (a) and (c) decrease initially and then increase. similarly, the density (ρ) has similar variations (increasing initially due to smaller particle size and cell volume but increasing laterally). here also the reason may be due to the fact mentioned above, about the substitution of (fe+3) with (zr+4). table 2 the lattice parameters (a) and (c) with density (ρ) for ba1-xzr0.5xal0.3fe11.7o19 (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5) samples a (å) c (å) ρ (g/cm3) x=0.0 5.40 21.36 6.786 x=0.1 5.26 20.70 7.319 x=0.2 5.34 21.02 6.935 x=0.3 5.40 21.26 6.648 x=0.4 5.39 21.21 6.631 x=0.5 5.28 20.8 6.986 3.2. ftir spectroscopy ftir (fourier transformation infrared analysis) was performed to get structural phase information about the m-type hexaferrites. ftir spectra for the samples ba1xzr0.5xal0.3fe11.7o19, (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5) are shown in figure 2, with the range 400cm-1-4000cm-1 of wave number. the two main absorption bands ν1 and ν2, typical for hexagonal ferrites, were observed in the range 410.39cm-1-451.59cm-1 and 572.76cm-1 604.75cm-1 which may result due to intrinsic stretching vibrations of oxygen and metal ion (fe-o), and are in octahedral and tetrahedral sites respectively (chawla et al., 2015). the existence of these bands confirms the hexaferrites structure of our sample (veisi, yousefi, amini, shakeri, & bagherzadeh, 2019). the bands range of 3200cm-1-3500cm-1 shows the humaira akhtar shahia, muhammad shahzad shifa, zeshan mehboob, muhammad hashim, faseeh ur raheem 49 presence of o-h group or moisture.in the samples (almessiere et al., 2019; li et al., 2013). absence of this range in our samples shows that the reactions were completed. the slight bending at 948.61cm-1, 1394.17cm-1 and 1534.21cm-1 show the weak bonds of c-o, –ch3 and c-h respectively (aparna, 2016; temuujin et al., 2004), which may be present in the starting materials. figure 3.2: ftir spectra for the samples ba1-xzr0.5xal0.3fe11.7o19 (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5) 3.3. scanning electron microscopy (sem) the sem micrograph of all our samples ba1-xzr0.5xal0.3fe11.7o19, (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5) are shown in figure 3 given below. as it is clear from the sem micrographs, particles of all the samples are plate like, with hexagonal irregular shape and compact arrangement (aparna, 2016). the plate like structure is the characteristics of hexaferrites (topkaya, auwal, & baykal, 2016). the morphology of the particles and their grain size appears to be porous, non-uniform and show agglomerations, which agrees very well with the literature. this morphology may arise due to the fact that the particles of our hexaferrites samples are smaller in size and magnetic in nature (temuujin et al., 2004). the overall view of the micrographs shows the particle size to decrease initially, which is the result of the addition of smaller size zirconium (zr+4) ions in place of barium having larger radii. (christy et al., 2017). and then particle size seems to increase due to substitution of iron (fe+3) with zirconium (zr+4), as zirconium has no particular preference for occupation at tetrahedral site of barium or bi pyramid site of 2b or 4f1 of tetrahedral of iron (fe+3). in later cases particle size should increase due to larger ionic radius of zr+4 as compared to (fe+3) (gunanto et al., 2016). journal of materials and physical sciences 2(1), 2021 50 sample-1 sample-3 sample -5 sample-2 sample-4 sample-6 figure 3: sem micrograph of ba1-xzr0.5xal0.3fe11.7o19, (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5) 3.4. uv analysis the prepared samples ba1-xzr0.5xal0.3fe11.7o19, (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5) were analyzed by uv-vis spectrometer. the optical band gap plots these samples are shown below in the figures 4. optical properties of the samples were studied by using uv-visible nir technique in the range of 200 nm-1200 nm. the energy band gap was calculated by using tauc method for each sample (tauc, 1974). the energy band gap was in the range 2.09ev 5.15ev, which is in full agreement with that of m-type hexaferrites (ali et al., 2021). the energy band gap value for each sample is 2.09ev, 2.84ev, 5.15ev, 3.45ev, 3.30ev and 3.08ev respectively. this band gap variation may correspond to s, p, d spin exchange interactions among the delocalized sor ptype band electrons of fe and o atoms respectively and the localized d-electrons of the transition metal zr ions, replacing the cations. also, the initial increase in optical band gap energy depends upon the decrease in grain size of the nanoparticles at start, on the zirconium doping. (r. b. bylsma., 1986). but afterwards the decrease in band gap energy may be due to increase in the crystallite size later on (christy et al., 2017). also, absorption peak lies between 237.9 nm -252.13 nm, which agrees very well with the abovementioned literature. humaira akhtar shahia, muhammad shahzad shifa, zeshan mehboob, muhammad hashim, faseeh ur raheem 51 figure 4: uv-vis spectra of ba1-xzr0.5xal0.3fe11.7o19 (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5) 4. conclusion in our present work, zr-al substituted m-type barium hexaferrites ba1xzr0.5xal0.3fe11.7o19, (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5) are prepared by co-precipitation method. we preferred this technique due to its low cost, effectiveness, particle size control quality. the xrd results confirmed their hexagonal structure. the lattice parameters a and c, cell volume and particle size were observed to decrease initially, due to zirconium addition and then starts to increase, which may be the result of substitution of zirconium (zr+4) with iron (fe+3), having smaller size. but the x-ray density was observed to increase initially, with the zirconium addition but then decrease. it might be due to the abovementioned reason. the crystallite size is found in the range of 9.43 nm-18.86 nm, which is the best for high density recording media. ftir technique was used in the range of 400 cm1-4000 cm-1. two particular bands in the range 400 cm-1-600 cm-1 confirmed the m-type hexagonal structure formation. the sem images showed the particles were, mostly, plate like structured. therefore, the hexaferrites formation was confirmed. sem images also showed the decrease in grain size of the nano particles initially, and then grain size is decreased, which agrees very well with the xrd results. uv visible spectrum analysis provided the information about the optical properties of our nanomaterial sample. the energy band gap was found in the range of 2.09 ev-5.15 ev and absorption peaks lie between the range 237 nm-252.13 nm. this variation in energy band gap and absorbance peaks, is due to the variations in particle size on zirconium addition and agrees well with the energy band gap variation in m-type barium hexaferrites. journal of materials and physical sciences 2(1), 2021 52 references abbas, w., ahmad, i., kanwal, m., murtaza, g., ali, i., khan, m. a., . . . ahmad, m. 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(1990). magnetic properties of anisotropic sr-la system ferrite magnets. ieee transactions on magnetics, 26(3), 1144-1148. doi:10.1109/20.53989 https://doi.org/10.52131/jmps.2021.0202.0018 78 journal of materials and physical sciences volume 2, number 2, 2021, pages 78 87 journal homepage: https://journals.internationalrasd.org/index.php/jmps investigation to understand the co ions inclusion in ba3sno antiperovskites structure naveed jafar1, g. murtaza1*, ghazanfar nazir2*, adeela rehman3 1 centre for advanced studies in physics, gc university, lahore 2 department of nanotechnology and advanced materials engineering, sejong university, seoul 05006, republic of korea 3 department of chemistry, inha university, 100 inharo, incheon 22212, south korea article info abstract article history: received: september 14, 2021 revised: november 12, 2021 accepted: december 29, 2021 available online: december 31, 2021 the current research focuses on the fabrication and characterization of barium tin oxide antiperovskite oxide ba3sno. bao and sn2o were used as precursors to synthesise the ba3sno by using solid state ceramic method. co ion has been implanted using pelletron accelerator with different doses 1013, 5×1013, 1014 ions/cm2. the study includes the investigations of penetration depth range of co ions in the target material, structural, surface morphology, verification of elemental composition, and band gap energy by using the characterization techniques srim, xrd, sem, edx, ftir, and uv-vis spectroscopy respectively. phase identification of desired material assures by xrd. sem results showed that the rough and sharp rod shape varies into a very smooth and fine granular shape by ion implantation. edx plots confirm the existence of basic elements like ba, sn, co and o. the ftir identify the unknown material and components which confirmed the formation of b3sno and incorporation of co ions. uv-vis spectroscopy results revealed that increasing the implanted ion dose causes a slight increase in band gap energy from 2.61 to 2.88 of this material. the obtained results allow us to conclude that the prepared sample contains a fine structure with no impurity. therefore, we can say that this process is ideal for obtaining fine structured ba3sno. keywords: ba3sno antiperovskites structure srim xrd ftir sem edx © 2021 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding authors’ email: gmrai@gcu.edu.pk, gnazir@sejong.ac.kr 1. introduction generally, the perovskites are symbolized by the formula abx3. if the position of a and x are exchanged, then the new resultant class of material is formed which is called antiperovskite which exhibits cubic or pseudo-cubic structure (oudah et al., 2016). then the general formula for antiperovskite is x3ba, where ‘b’ and ‘a’ are two anions of different sizes and ‘x’ is a cation. in antiperovskite oxide the atom ‘b’ may be si, ge, sn and pb, ‘a’ is oxygen and ‘x’ may be an element of group iia such as ba, sr, and ca. such as perovskite oxides, the antiperovskite oxides also have many physical properties such as superconductivity, electrolytic, electrostriction, piezoelectric, thermoelectric properties, magnetic and optical properties. antiperovskite oxides have many technological uses like quantum computing, flat panel display, biosensors spintronic devices as well as magnetoresistive devices (arakawa, kurachi, & shiokawa, 1985; bokov & ye, 2006; israel, calderón, & mathur, 2007; kim, qi, dahlberg, & li, 2010; mathur et al., 1997). both materials of perovskite oxides and anti-perovskite oxides may be alleviated in other structures such as hexagonal orthorhombic structures. in previous study, scientists have extensively explored the innovative characteristics of anti-perovskites. the anti-perovskites have attained vast desirability to be investigated for the numerous industrial utilities due to https://journals.internationalrasd.org/index.php/jmps mailto:gmrai@gcu.edu.pk mailto:gnazir@sejong.ac.kr naveed jafar, g. murtaza, ghazanfar nazir, adeela rehman 79 their vide band gap range. the anti-perovskites which have small band gap are potential applicants for numerous optical devices. the anti-perovskites can be appear as non-metals, semiconductors, metals as well as superconductors therefore they have interesting material behaviors (bilal, jalali-asadabadi, ahmad, & ahmad, 2015). antiperovskite oxides changed their properties by varying the temperature and pressure. in 2010, hichour et.al (hichour et al., 2010) explored the ansr3 (a= as, sb and bi) antiperovskite pressure-dependent properties and perceived narrow direct bandgap proposed appropriate optical applications. some experiments revealed that, sr3pbo, ca3pbo as well as ba3pbo are strong nominees for topological crystalline insulators (hsieh, liu, & fu, 2014; samal, nakamura, & takagi, 2016) and thermoelectric applications (okamoto, sakamaki, & takenaka, 2016). the significant values of this atom configuration were that the ‘b’ atom in x3ba antiperovskite attains a negative charge state (e.g., b4–), the also strong overlap of ‘p’ states of ‘b’ and ‘d’ states of ‘x’ atoms (batool, alay-e-abbas, & amin, 2017). it is reported that the lattice constant of the cubic structure increases as cation changes from ca to ba and it may be increased by increasing the concentration of doped ions (hassan, arshad, & mahmood, 2017). the crystal structure of antiperovskite ba3sno is described as ‘ba’ is a cation and ‘sn’ as well as ‘o’ are the anions. in the cubic structure of antiperovskite, ‘o’ atoms are placed at the corner of the cube, whereas ‘sn’ occupied octahedral site and the ‘ba’ are placed on the faces of the cube. this study is an exploration of the properties of novel antiperovskite material i.e. ba3sno. synthesize and characterization of antiperovskite oxide ba3sno and understanding the inclusion of co ions in barium tin oxide was the main purpose of this research work. we also analyzed the effect of co ions implantation in ba3sno. the synthesis of ba3sno had to be approached from an adequate route as it has not been synthesized before. 2. experimental procedure the materials were selected on the basis of properties, cost and thier suitability. bao and sno2 with desired molecular weight by stoichiometric calculations were used for the preparation of ba3sno. the solid state method was used in this work to prepare ba3sno; as at room temperature the solid materials do not recombine and react. therefore, initially materials are heated at higher temperatures to complete the reaction properly (callister jr & rethwisch, 2020). both precursors bao and sno2 were ground for 2 hours in a mortar pestle and then calcinated the mixture at 900oc for 6 hours in the furnace. after calcination, the sample was again ground for 30 min. by using a hydraulic press machine, the desired pellets were formed of 1.5 g at 3000 psi. the whole synthesis process was done under consideration of a given equation: 3bao + sno2 → ba3sno + 4o (1) fine ba3sno was obtained after sintering the pellets at 600 oc for 2 hours in the furnace. finally, the co ions are implanted on the host material ba3sno by pelletron accelerator with different doses 1013, 5×1013, 1014 ions/cm2. phase identification was done by using an x-ray diffractometer (xrd). 3. results and discussions 3.1. srim analysis the concept of effective charge was used for establishing the charge state of an ion inside a target material. when sample is exposed to ion a damage occured inside the material which is observed by srim. in this project, the penetration of cobalt is observed on the target sample of ba3sno, which is irradiated with various implantation fluence. figure 1 shows the penetration shape of co with an energy of 500 kev inside the prepared materials. the penetration depth range of co is about 1 µm. journal of materials and physical sciences 2(2), 2021 80 figure 1: depth and range of implanted co ions in ba3sno 3.2. structural analysis x-ray diffraction (xrd) patterns of all the samples are shown in figure 2. xrd result of ba3sno in figure 2(a), the pure untreated sample that represents the existence of an higher intensive peak at angle 31.6o with plane of (111). this is matched with the reported xrd card (jcpds card no 01-083-1868). the xrd patterns represents the crystalline phase formation of ba3sno and there is no extra peak either due to sno2 or any other contamination. the diffraction peaks appear at angles (2θ) of 25.29°, 45.08°, 47.68°, 55.52°, 64.83°, 69.04° and 72.60°, which assigned planes of the crystal lattice of hkl 110, 200, 220, 311, 321, 320 and 411, respectively. the sample is exposed to co ions having the dose of 1×1013 ions/cm2 (see figure 2(b)). it is noted that the maximum peak at 31.6o becomes sharper that showing an increase in intensity. it confirms that the crystallinity and quality of the material can enhanced with ion implantation at low influence. the peak appears at angle of 44o denotes co ions with the plane 111*. the crystallite size is equal to 37 nm and lattice constant is equal to 4.91å. volume of the cell is equal to 118.38 å3 (see table 1). enhancement in crystallinity may be due to the electronic excitations or ionization energy (electronic energy loss). when fast moving ion enter inside a solid it loss some of their energy during an elastic collisions between ion and atom of the solid (agarwal et al., 2006). table 1 shows that the crystallite size varies from 29 to 37 nm which verify the results that the crystallinity of the material improves after co ion implantation. similarly, in figure 2(c) because of high dose ions of value 5×1013 some additional peaks are also appeared. the peak appears at angle of 44o may be due to co ions, which is evidence for the implanted co ions. the lattice constant increases from 4.88 to 5.15 å due to co ions. the peak appears at angle of 24.6o shows the secondary phase due to bao that is matched with the card (jcpds # 00-001-0746). the increase of lattice constant may be due to the lattice distortion caused by co ions while the secondary phase caused due to the short time of calcination. the volume of the unit cell is 143.82 å3 that is changed from the base sample. at higher dose of 5×1013 ions/cm2 the crystallite size of is found to be 31.5 nm (see table 1) that is smaller than the crystallite size of dose in order of 1013 ions/cm2. it naveed jafar, g. murtaza, ghazanfar nazir, adeela rehman 81 signifies that the crystallinity decreases, and density of grains increases (li & bergman, 2009; varadhaseshan, meenakshi sundar, & prema, 2014). table 1 ensures the presence of co ions because the lattice increases from 4.88 to 5.15å. figure 3 (a, b, c, d): xrd graphs of the pure and doped samples similarly, in figure 2(c) because of high dose ions of value 5×1013 some additional peaks are also appeared. the peak appears at angle of 44o may be due to co ions, which is evidence for the implanted co ions. the lattice constant increases from 4.88 to 5.15 å due to co ions. the peak appears at angle of 24.6o shows the secondary phase due to bao that is matched with the card (jcpds # 00-001-0746). the increase of lattice constant may be due to the lattice distortion caused by co ions while the secondary phase caused due to the short time of calcination. the volume of the unit cell is 143.82 å3 that is changed from the base sample. at higher dose of 5×1013 ions/cm2 the crystallite size of is found to be 31.5 nm (see table 1) that is smaller than the crystallite size of dose in order of 1013 ions/cm2. it signifies that the crystallinity decreases, and density of grains increases (li & bergman, 2009; varadhaseshan et al., 2014). table 1 ensures the presence of co ions because the lattice increases from 4.88 to 5.15å. similarly, in figure 2(d) the intensity of the main crystalline peak at (111) is decreased reduction ensured by an increment in fwhm which implies that the crystallite size reduces. the crystallite size for 5×1013 ions/cm2 dose is 31.5 nm but for the dose of 1×1014 ions/cm2 crystallite size is 30 nm. the lattice constant increases from 4.88 å to 5.23 å (agarwal et al., 2006). table 1 calculated lattice parameters of pure and co doped samples samples lattice constants (å) a=b=c cell volume (å3) v crystallite size (nm) d pure 4.88 116.50 29 1013 4.9 118.38 37 5×1013 5.15 143.82 31.5 1014 5.23 136.27 30 20 30 40 50 60 70 80 50 100 150 200 250 300 350 400 in te n s it y (a .u ) 2 (degree) (110) (111) (111)* (211) (220) (311) (320) (411) (321) ( b ) 20 30 40 50 60 70 80 0 100 200 300 400 500 600 700 in te n s it y (a .u ) 2 (degree) (110) ** (110) (111) (200) (210) (111)* (220) (311) (310) (320) (411) *co **bao ( c ) 20 30 40 50 60 70 80 0 100 200 300 400 500 600 in te n s it y (a .u ) 2 (degree) (110) (111) (210) (111)* (211) (220) (311) (320) (411) ( d ) 20 30 40 50 60 70 80 50 100 150 200 250 300 350 400 450 in te n s it y (a .u ) 2 (degree) (110) (111) (200) (220) (311) (321) (320) (411) ( a ) journal of materials and physical sciences 2(2), 2021 82 3.3. surface analysis sem micrographs analysis in figure 3(a, b, c, d) displays the surface morphology of pure as well as doped ba3sno samples. since, melting point of magnetic ceramic material is very high, therefore for various materials at higher temperature o loss occurs before melting. a polycrystalline structure is formed by sintering. the prepared sample is calcined at temperature of 900oc for 8 hours. polycrystalline is formed from the bonded of tiny crystals together. figure 3(a) for the pure sample of ba3sno displays rod formation as well as a sharp and raw surface. the stout bright spots are also observed in figure 3(a, b, c, d) which shows pores inside the material (mujahid, sarfraz, & amin, 2015). figure 3(a, b, c, d): sem micrographs of untreated and treated samples (a) untreated (b) 1×1013 (c) 5×1013 (d) 1×1014 figure 3(b) displays that the gain growth occurs for co ion implanted of the dose 1013 ions/cm2. the calculated average grain size is 1.3 µm increases from 0.76 µm of pure sample and these results match with the xrd results. the morphology of the ba3sno changes from rough surface to a smaller dense surface. this is due to the energetic cobalt ions, when bombarded on material then it transfer their energy to ba3sno which lead to the formation required material (murtaza et al., 2011). similarly, both dopants with the dose of 5×1013 ions/cm2 as well as 1014 ions/cm2 ions reduces the grain size to produce microstructures. in figure 3(c) shows grain size is 0.8 µm for dose of 5×1013 ions/cm2 while figure 3(d) shows grain size is 0.7µ𝑚 for the dose of 1014 ions/cm2. since density of dopant (co) increases, which caused an increase of the grain boundaries. the increase of grain boundaries caused the decrease in grain size (park, jung, kim, & park, 2008). 3.4. edx analysis edx studies were performed to confirm an elemental composition of the material. as the basic elements are ba, sn and o. figure 4(a, b, c, d) shows edx spectra which indicate the peaks which ensure the existence of ba, o and sn in ba3sno sample. there is an extra peak of s which may be due to contamination or come from the sample holder. in figure 4(b, c, d) there is slight difference in peak’s intensity of co ion because ion dose increase from the value of 1×1013, 5×1013 and 1×1014 ions/cm2 (tabari, tavakkoli, zargaran, & beiknejad, 2012). (a) (b) (c) (d) naveed jafar, g. murtaza, ghazanfar nazir, adeela rehman 83 figure 4(a, b, c, d): edx graphs of pure and doped ba3sno 3.5. ftir analysis it has been shown that ftir spectroscopy is proper and suitable device for understanding the functional group of any compound. ftir analysis confirmed the bond formation of barium tin oxide and the incorporation of ‘co’ ions in the crystal lattice. figure 5 show the ftir spectra of the calcined material at temperature of 900oc for 8 hours. the broad peak observed at wavenumber of 1429 cm-1, is due to stretching vibration of ba-o bond (kumari, suresh, & rao, 2013; lu & schmidt, 2007; murtaza et al., 2011). the peak is at wavenumber of 3311.77 cm-1 is is due to the stretching vibration of o-h bond. the peaks at wavenumber of 850.62 cm-1 is due to absorption of co2 and stretching vibration of co32(durán, gutierrez, tartaj, bañares, & moure, 2002; lu & schmidt, 2008). similarly, the peaks at wavenumbers of 640.36 cm-1 and the 1721.36 cm-1 are due to the stretching vibration of sn-o and co-o, respectively (bazeera & amrin, 2017; varadhaseshan et al., 2014). all observed peaks are agreed with the reported data in the literature. figure 5: ftir spectra for pure and doped ba3sno 3500 3000 2500 2000 1500 1000 500 0 100 200 co +2 3 in te n s it y (a .u ) wave number(cm -1 ) (5´10 13 ) (1´10 13 ) (pure) (1´10 14 ) sn-o ba-o co-o (pure) dose(𝟏𝟎𝟏𝟑) dose(5×𝟏𝟎𝟏𝟑) dose(𝟏𝟎𝟏𝟒) journal of materials and physical sciences 2(2), 2021 84 3.6. bandgap analysis the optical characterization of pure and cobalt doped material was studied by uv-vis spectroscopy. it offers beneficial information about the bandgap study of semiconductor pure barium tin oxide and the effect of co ions implantation doping on the bandgap of the host material. a semiconductor is characterized by its electronic band structure. the energy difference between the highest occupied molecular orbital (homo) and the lowest unoccupied molecular orbital (lumo) is termed as bang gap energy (eg). the optical absorption study of the irradiated and pristine was carried out and the bandgap of the films have been calculated using tauc’s plot by plotting (αhʋ)2 versus hʋ and extrapolating the linear portion of the absorption edge to find the intercept with energy axis. the energy of on photon is calculated by the relation e= hc / λ. in the high energy absorption region dependence on photon energy is expressed by tauc’s equation. on the basis of tauc relation, the absorption coefficient ‘’a’’ for direct bandgap material is given by: α(hʋ) = b(hʋ − eg)m (2) from figure 6 of tauc’s plots, it is clear that the bandgap of ba3sno slightly varied from 2.61 to 2.88. the presence of co ions causes the change in the bandgap of barium sin oxide. tauc plots reveal that absorption is in the range of 200 to 800 nm. the reason for the increase in the energy bandgap in the visible region of exposed materials is because of the interstitial location formed by co ions. since, co is metal, which provides extra electrons so the existence of co ions at the interstitial location causes the charge transition between the narrow band of the localized co state and conduction state of the host which cause in increase in band gap (deepa et al., 2011). the increase of bandgap may because of dopant concentration, surface effects, lattice strain and quantum confinement effects (chen, lou, samia, & burda, 2003; nandan, venugopal, amirthapandian, panigrahi, & thangadurai, 2013; smith, mohs, & nie, 2009). figure 6: tauc plots results for pure ba3sno and doped ba3sno 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 ( h  )2 energy(ev) pure 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0.0 0.2 0.4 0.6 0.8 ( h  )2 energy(ev) dose 10 13 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0.0 0.2 0.4 0.6 0.8 1.0 1.2 ( h  )2 energy(ev) dose 5× 10 13 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0.00 0.01 0.02 0.03 0.04 0.05 0.06 ( h  )2 energy(ev) dose 10 14 naveed jafar, g. murtaza, ghazanfar nazir, adeela rehman 85 figure 7: reflectance graphs for pure ba3sno and doped ba3sno reflectance spectrum as shown in figure 7 for pure sample indicates the maximum reflectance of light heavily at 535 nm a green emission and has energy 2.32 ev. similarly, the figure for doped samples shows when the material is irradiated by co ions 1013 ions/cm2 a blue emission takes place at 464 nm and has an energy of 2.67. similarly, it is noted that decreasing values of wavelengths causes the increase in values of energy from 2.73 to 2.88 ev by variance in a dose of implanted co ions 5×1013 ions/cm2 and 1×1014 ions/cm2 correspondingly causes the violet emission which indicated that the sample corresponds the visible region. it is clear from the graph that there is no significant variation in band edge after the irradiation, but the absorption lies in the visible region. this implies that the basic crystal structure is not changed. 4. conclusion in this work, antiperovskite oxide ba3sno was successfully synthesized using solid state method and subsequently, co ions with different ions fluence were embedded into ba3sno structure using the ion implantation route. xrd results confirm the cubic structure of barium tin oxide. results also reveal that the lattice parameters increase from 4.88 å to 5.2 å after co ion implantation that becomes more prominent at the highest dose 1014 ions/cm2. the crystallinity of material is enhanced for low values 1013 ions/cm2 and decreases by increasing the fluence up to dose 1014 ions/cm2. the rods shape formation of the undoped sample changes into a fine granular shape by increasing the fluence from 1013 to 1014 ions/cm2 of co ions, which has been confirmed by fe-sem. surface morphology also shows the grain size reduces from 1.33 to 0.7 µm by increasing the higher dose 1014 ions/cm2 match with the xrd results. ftir study confirms the formation of barium tin oxide by showing that the functional groups are present in all the samples and ensures the presence of co ions. uv-vis spectrometer was used to analyse the energy band gap of ba3sno. the results exhibit the increases of energy bandgap from 2.61 to 2.88 ev by 400 500 600 700 800 0.04 0.06 0.08 0.10 0.12 0.14 r e fl e c ta n c e (a .u ) wavelength(nm) dose 10 14 400 500 600 700 800 0.01 0.02 0.03 0.04 0.05 0.06 r e fl e c ta n c e (a .u ) wavelength(nm) pure 400 500 600 700 800 0.05 0.10 0.15 r e fl e c ta n c e (a .u ) wavelength(nm) dose 10 13 400 500 600 700 800 0.01 0.02 0.03 r e fl e c ta n c e (a .u ) wavelength(nm) dose 5×10 13 journal of materials and physical sciences 2(2), 2021 86 increasing the fluence of ions from 1013 to 1014 ions/cm2. from all the investigations, the conclusion drawn that the inclusion of co is fruitful to alter the optical properties of ba3sno. references agarwal, d. c., kumar, a., khan, s. a., kabiraj, d., singh, f., tripathi, a., . . . avasthi, d. k. 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(2014). on the preparation, structural and magnetic properties of zno:co nanoparticles. the european physical journal applied physics, 66(1), 10602. doi:10.1051/epjap/2014130316 https://doi.org/10.1016/j.ceramint.2007.01.002 https://doi.org/10.1016/j.surfcoat.2010.11.015 https://doi.org/10.1016/j.surfcoat.2008.08.004 https://doi.org/10.52131/jmps.2020.0102.0010 98 journal of materials and physical sciences volume 1, number 2, 2020, pages 98 108 journal homepage: https://journals.internationalrasd.org/index.php/jmps synthesis and characterization of praseodymium doped nickel zinc ferrites using microemulsion method h. m. noor ul huda khan asghar1, muhammad kamran nawaz1, rafaqat hussain1, zaheer abbas gilani1* 1 department of physics, balochistan university of information technology, engineering & management sciences, quetta 87300, pakistan article info abstract article history: received: october 03, 2020 revised: november 27, 2020 accepted: december 29, 2020 available online: december 31, 2020 spinel ferrites nanoparticles are plays important role in our daily life. praseodymium doped nickel zinc ferrite nanoparticles having general formula ni0.3zn0.7prxfe2-xo4 (x=0.00, 0.025, 0.050, 0.075 and 0.1) were synthesized by microemulsion method. x-ray diffraction (xrd) was used to find different parameters of crystalline size. the development of the fcc spinel structure was observed by xrd data. the most intense peak of the xrd was identified at 2θ=35º.from debye sherrer's formula, calculated the crystalline size 15nm to 29nm ranges. the lattice constant calculations are decreased with the doping of praseodymium (pr3+) contents. the x-ray density increases as the concentration of praseodymium (pr3+) doping increases, because praseodymium (pr3+) ion has a greater molar weight than fe3+ ion. the absorption band spectra are analyzed by using fourier transform infrared spectroscopy (ftir). the absorption bands ʋ1 is known as octahedral stretching bands were found to be in the range of 414 cm-1 and ʋ2 is the tetrahedral stretching band were found to be in the range of 530cm-1. dielectric properties of praseodymium doped nickelzinc ferrite were measured with impedance analyzer in the frequency of 1 mhz to 3 ghz range. when pr3+ content concentration increases, the dielectric characteristics, such as dielectric constant, dielectric loss, and tangent loss were also decreased. these measured dielectric characteristics showed that these nanomaterials may be used in higher frequencies devices. keywords: praseodymium nickel−zinc ferrite spinal ferrites microemulsion xrd ftir dielectric properties © 2020 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: zagilani2002@yahoo.com 1. introduction developments in nanotechnology have revealed a successful applications for several materials that will be used in advanced technologies (ahmed, bishay, & radwan, 2002). ferrites have attracted the attention of scientists and researchers due to their numerous applications in transformer cores, magnetic memories, high-frequency circuits, and electronic circuits. semiconductors and magnetic materials have unique features, and they are used in a variety of electrical device (muhammad azhar khan, islam, ishaque, & rahman, 2012). the chemical formula for spinel ferrites is ab2o4 (lodhi et al., 2014). many methods have been developed to improve the fundamental features of nano-ferrites by including other metal ions and using different production techniques. rare earth ions are an excellent substitute for increasing spinel ferrites characteristics (m azhar khan, islam, ishaque, & rahman, 2011). soft ni-zn ferrites are inexpensive materials with intriguing electrical and magnetic properties. microwave devices such as isolators, transformers, and https://journals.internationalrasd.org/index.php/jmps mailto:zagilani2002@yahoo.com journal of materials and physical sciences 1(2), 2020 99 circulators have all used these ferrites (al-hilli, li, & kassim, 2009). chemical composition, annealing process, and kind of doped metal ions all influence the inherent properties of ferrites, such as permittivity, dielectric losses, and conductivity (al-hilli, li, & kassim, 2012; jing, liangchao, & feng, 2007). several synthetic processes, including as coprecipitation, sol–gel, microemulsion, ceramic, and hydrothermal methods are used to produce highquality doped praseodymium spinel ferrites (sun & sun, 2007). the rare earth doped nickel-zinc ferrites are prominent, due to their significance in microwave devices. the incorporation of metal ions with larger ionic radii into the spinel structure results in structural distortion as well as changes in electrical and dielectric features. in compared to other simple ferrites, the different forms of substitution in nickel-zinc ferrites indicate a reasonably good relaxation and conduction mechanism (iqbal, islam, ali, sadiq, & ali, 2014). according to researches, different rare earth ions doping modifies the behaviour of spinel ferrites (al-hilli et al., 2012). furthermore, doping rare earth elements in these nanomaterials can improve electrical properties and optical properties. a lot of study has gone into changing the characteristics of ferrites by doping rare earth cations in these ferrites (sun & sun, 2007). the influence of pr3+ concentration on structural, spectral, and dielectric properties has been presented in this work. ni0.3zn0.7prxfe2-xo4 (x= 0.0, 0.025, 0.05, 0.075 and 0.1) spinel ferrites was prepared via a micro-emulsion technique. the purpose of this research is to improve the structural and dielectric properties of these nanocrystalline ferrites so that they can be used in the manufacture of microwave devices (junaid et al., 2016). 2. experimental procedure praseodymium doped nickel−zinc ferrites with general formula ni0.3zn0.7prxfe2-xo4 (x= 0.0, 0.025, 0.05, 0.075 and 0.1) was synthesized by using microemulsion method. this method wasuseful because it reduces cation nucleation compared to other methods such as sol-gel and co-precipitation. the chemicals were used for preparation of solution are as follows: nickel nitrate-6 hydrate (ni(no3)2.6h2o)(m.w=290.81)(99%), zinc nitrate hexahydrate (n2o6zn.6h2o)(m.w=297.46)(98%), praseodymium nitrate hexahydrate (n3o3pr.h2o) (m.w=435.01)(99.9%), iron(iii) nitrate9 hydrate (fen3o9.9h2o) (m.w=404 ) (98%), cetyltrimethylammonium bromide (c19h42brn) (m.w=346.45) (99%) were weighted using precise digital balance. the praseodymium, nickel, zinc and iron sample solutions were prepared in distilled water, then combined to produce the mixed solution. the magnetic stirrer was used to stir the solution at 50°c. ctab solution was added to the mixture of the solution. aqueous ammonia solution was added to maintain the ph value up to 10. the mixture of all samples were stirred continuously for 5 hours. after stirring, all of the ni0.3zn0.7prxfe2-xo4 solutions were placed in the cupboards overnight. during this time, the precipitation was settled down. to reduce the value of ph, all samples were washed with deionized distilled water. the washing was carried out until the ph value reached a neutral level of 7. to remove the water, the samples of various compositions were dried in a thermostat oven at about 80 °c. methanol was used to clean and wash the mortar and pestle before grinding. the samples were grinded in a mortar and pestle after drying. after each grinding, the mortar and pestle were washed and dried to avoid contamination. all samples were placed in muffle furnace for annealing at 700°c for 3 hours. the samples was pelletized with a 4.5 ton pressure by using hydraulic press. the prepared ferrites samples were characterized by using different characterization techniques, the xrd was done using a panalytical xpert pro to examine the crystal structure and determine numerous crystalline structure parameters. the tetrahedral and octahedral stretching bands were investigated using ftir. the dielectric characteristics of synthesized ferrite material were investigated using an impedance analyzer. different dielectric properties, including as the dielectric constant, dielectric loss, tangent loss, ac conductivity, real and imaginary parts of impedance, and modulus, were calculated in the frequency range of 1mhz to 3ghz, and their variations were investigated as pr3+ content increased. 3. results and discussion 3.1. xrd analysis praseodymium doped nickel zinc ferrite nanoparticles having general formula ni0.3zn0.7prxfe2-xo4 (x=0.00, 0.025, 0.05, 0.075and 0.1) was effectively prepared by microemulsion technique. the samples were annealed at temperature of 700℃ for 5hours. h. m. noor ul huda khan asghar, muhammad kamran nawaz, rafaqat hussain, zaheer abbas gilani 100 xrd was used to analysis crystal structure and the formation of crystalline phase powder, which is a very useful technique for calculating crystalline parameters such as crystalline size, lattice constant, bulk density, x-ray density and dislocation density etc. the xrd pattern shows very sharp peaks, indicating the formation of the crystalline phase of nickelzinc ferrite. the most intense peak on the xrd was identified at 2θ=35º, which is considered to be the most intense peak for cubic spinel structure. the peaks that correspond to the xrd trend are evaluated and assigned the numbers (220), (311), (400), (422), (511), (440), and (531) correspondingly. the fcc spinel structure is defined by these peaks.jcpds card number 22-1086 confirms these peaks. two impurity peaks can be seen, one at 2θ =33.27º and the other at 2θ =49.54º. these impurity peaks could be caused by pr3+ insolubility in the octahedral site (sheikh et al., 2019). the crystalline size of the prepared ferrites can be determined by using the debye sherrer's formula given as: dm = 𝐤 𝛃𝐜𝐨𝐬𝛉 (1) in the above equation ‘k’ is equal to 0.9 (constant),  is wavelength of x-ray in å. β is fwhm for intense peak of xrd, θ is the bragg diffraction angle. the crystalline size was determined to be in the 15nm to 29nm range. with the substitution of pr3+, the crystalline size varied in an inhomogeneous form. this inhomogeneous behavior of crystalline size is due to the formation of a secondary phase (warsi et al., 2017). the nelson relay function determines the lattice constant as a function of pr3+ concentration, which is given as: a= d (h2 + k2 + l2)1/2 (2) where ‘hkl’ is the index of the xrd reflection peak and ‘d’ is the inter planer spacing. the average lattice constant in the range of 8.360å−8.380å. first lattice constant decreases with increase of pr3+ substitution ion contents and then increases, finally at the end lattice constant decreases (aslam et al., 2019). the x-ray density of the prepared nanoferrites was calculated by using the following formula as: ρx = 8m/naa3 (3) where ‘m’ denotes molecular weight, ‘na’ denotes avogadro's number, and a3 denotes the lattice constant. the x-ray density varies from 5.39 to 5.62 g/cm3 depends upon the concentration. it is also observed that x-ray density and concentration are approximately linear. as pr3+ concentration is increased, x-ray density also increased (gao, wang, pei, & zhang, 2018). the bulk density was calculated by using the formula give as: ρm=m/v (4) where ‘m’ is mass of prepared pellets and ‘v’ is volume of the prepared pellets. bulk density varies between 3.07 to 3.58 g/cm3. bulk density shows an in-homogeneous variance with concentration. the bulk density first increases then decreases and then again increases and the end it again decreases due to the concentration of pr3+ doping. the lattice strain (ɛ) of the ferrites was determined by formula given as: ɛ = β/4*tanθ (10−3) (5) the lattice strain was calculated to be in the range of 3.92 ×10-3 to 7.19 ×10-3. the lattice strain was found to be increases in-homogeneously with respect to concentration of pr3+ substituent. the value of lattice strain is maximum at x= 0.075 and then decreases. the micro-strain of prepared ferrites was calculated by using the following formula: micro-strain = β×cosθ/4 (10−3) (6) where β is fwhm of most intense peak xrd. the micro strain values was calculated to be in the range of 1.16 ×10-3 to 2.18 ×10-3. the micro-stain was found to be increases journal of materials and physical sciences 1(2), 2020 101 with respect to concentration of pr3+ substituent. the micro-strain value is maximum at concentration of pr3+ substituent is at x= 0.075. the dislocation density of prepared samples was determined by following formula: ծ = 1/d2 (1015) (7) figure 1: xrd analysis of ni0.3zn0.7prxfe2-xo4 (x=0.00, 0.025, 0.050, 0.075 and 0.1) where ‘d’ is the crystalline size, the dislocation density was measured to be in the range of 4.20×1015 to 7.27×1015. the dislocation density was found to be increases with respect to concentration of pr3+ substituent. the dislocation density value is maximum at concentration of pr3+ substituent is at x= 0.075. the stacking fault of the prepared nanoparticles is calculated by the formula: stacking fault = 2 π2/45√3(tanθ) (8) the stacking fault was observed to be decreases and then increases to a certain value, and again finally decreases. this inhomogeneous behaviour of the stacking fault is due to annealing temperature (brightlin & balamurugan, 2016). figure 2: concentration vs crystalline size of ni0.3zn0.7prxfe2-xo4 (x=0.00, 0.025, 0.050, 0.075 and 0.1) h. m. noor ul huda khan asghar, muhammad kamran nawaz, rafaqat hussain, zaheer abbas gilani 102 table 1 different structural parameters of xrd for composition of ni0.3zn0.7prxfe2-xo4 (x=0.00, 0.025, 0.050, 0.075 and 0.1) parameter x = 0 x = 0.025 x = 0.05 x = 0.075 x = 0.1 crystalline size (nm) 29.672 24.920 23.133 15.825 24.414 lattice constant a(å) 8.379 8.371 8.367 8.374 8.360 cell volume (a3) 588.295 586.507 585.843 587.306 584.358 x-ray density (g/cm3) 5.398 5.463 5.517 5.552 5.628 bulk density (g/cm3) 3.0738 3.4262 3.2135 3.5834 3.4429 lattice strain×10-3 3.92261 4.55211 4.9105 7.1933 4.6544 micro strain×10-3 (lines-2/m-4) 1.1678 1.3904 1.49786 2.18945 1.4192 dislocation density×1015 (lines/m2) 4.2079 5.0194 4.5202 7.2736 6.0952 stacking fault 0.4473 0.4467 0.4470 0.4475 0.4471 3.2. ftir spectroscopy fourier transform infrared spectroscopy (ftir) is a technique used to investigate spinel crystal structure of the prepared sample of composition ni0.3zn0.7prxfe2-xo4 (x=0.00, 0.025, 0.050, 0.075 and 0.1). the ftir spectra shows two frequency bands, one of which is higher frequency band ʋ2 at around 530 cm-1 and the second is lower frequency band ʋ1, at around 400 cm-1. these samples have cubic spinel structure since the two main absorption bands ʋ1 is known as octahedral stretching bands are found to be in the range of 414 cm-1 and ʋ2 is the tetrahedral stretching band are found to be in the range of 530cm-1. the tetrahedral and octahedral frequency bands are investigated in this analysis. because of the tetrahedral site of intrinsic stretching vibrations, the absorption peaks are called high frequency bands ʋ1. octahedral stretching bands are covered by low frequency band ʋ2 (batoo et al., 2017). the characteristics feature of spinel ferrite structure are shown in these bands.it is observed that low frequency band ʋ1 value remains static. the lattice constant variations were responsible for the slight shift of high frequency band ʋ2 and low frequency band ʋ2 towards higher frequency bands with an increase in pr3+ constituent. the fe3+-o2stretching vibrations were influenced by the change in lattice constant, resulting in a shift in band position (gilani et al., 2015). the tetrahedral and octahedral sites for force constants k0 and kt have been calculated using the following relations: ko = 0.942128m (ʋ2)2/ (m+32) (9) kt = √2ko ʋ1/ ʋ2 (10) where ‘m’ is molecular weight of prepared samples, ʋ1 and ʋ2 are the frequency bands. the tetrahedral and octahedral radii was calculated by using the following formulas: rt= a√3 (u−0.25) –ro (11) ro= a (5/8−u) –ro (12) where ‘a’ is lattice constant and ‘u’ is oxygen positional parameter, the value of oxygen positional parameter is 0.375. table 2 different parameters in ftir studies parameters x = 0.0 x = 0.025 x = 0.05 x = 0.075 x = 0.1 molecular weight (gm/mol) 239.06402 241.19059 243.31715 245.44372 247.57029 ʋ1 (cm -1) 540 537 540 537 540 ʋ2 (cm -1) 414 414 414 414 414 ko(dyne/cm -1 )*105 1.424141 1.425625 1.427086 1.428524 1.429941 kt(dyne/cm -1 )*105 2.627008 2.615135 2.63244 2.620454 2.637707 r0 0.080733 0.079958 0.079649 0.080419 0.080488 rt 0.052232 0.051561 0.051293 0.05196 0.05202 journal of materials and physical sciences 1(2), 2020 103 figure 3: ftir spectra of ni0.3zn0.7prxfe2-xo4 (x=0.00, 0.025, 0.050, 0.075 and 0.1) 3.3. dielectric properties the dielectric properties of synthesized praseodymium doped ni-zn ferrite nanoparticles having general formula ni0.3zn0.7prxfe2-xo4 (x=0.00, 0.025, 0.050, 0.075, and 0.1) were measured using an impedance analyzer. these characteristics are critical in determining the prepared ferrite is suitable for use in ultra-high-frequency devices. the synthesis technique, material composition, and cation orientation all affect these properties. the dielectric characteristics of synthesized ferrite nanoparticles were determined from 1 mhz to 3 ghz (parveen et al., 2019). 3.3.1.dielectric constant and dielectric loss the figure 4(a) and figure 4(b) shows the dielectric constant (ɛ') and dielectric loss (ɛ'') decreases with increasing of frequency. in electron conduction, grain boundaries had a significant impact as compared to grains at low frequencies. the free and localized charge carriers were identified based on the observed dielectric constant and losses. the normal dielectric dispersion was observed that the dielectric constant dropped as frequency raised. at low frequencies, dispersion can contribute to the polarization phenomenon. the reduction in dielectric constant was attributed to both maxwell wagoner's model and koop's theory. it was thought that dielectric material was made up of well-conducting regions called grains that were separated by resistive regions called grain boundaries. since charge carriers are displaced locally, polarization occurs between fe2+ and fe3+ at grain boundaries which are in octahedral sites. the hopping mechanism causes electrons to accumulate at grain boundaries due to high resistance, resulting in space charge polarization. dielectric dipoles that followed the variance in applied field provided a high dielectric constant at low frequencies (junaid et al., 2016). h. m. noor ul huda khan asghar, muhammad kamran nawaz, rafaqat hussain, zaheer abbas gilani 104 figure 4: (a) dielectric constant vs frequency (b) dielectric loss vs frequency table 3 different parameters of dielectric properties for ni0.3zn0.7prxfe2-xo4 (x=0.00, 0.025, 0.050, 0.075 and 0.1) parameters frequency x = 0.00 x = 0.025 x = 0.05 x = 0.075 x = 0.1 dielectric constant 1mhz 4.027146 8.191817 8.638792 8.521431 6.476407 1ghz 3.684943 2.891025 3.039607 1.732787 3.506363 3ghz 3.538591 2.970498 2.993035 1.748285 3.317121 dielectric loss 1mhz 1.047309 6.292897 7.818412 9.375467 3.352912 1ghz 0.1281894 0.08786879 0.08285637 0.08466826 0.04852595 3ghz 0.1014174 0.1603908 0.05450426 0.0221134 0.1812719 tangent loss 1mhz 0.2600623 0.768193 0.9050353 1.100222 0.5177118 1ghz 0.03478736 0.03039364 0.02725891 0.04886246 0.0138394 3ghz 0.02866039 0.05399459 0.01821036 0.01264863 0.05464737 ac conductivity 1mhz 4.37885e-05 0.00033173 0.00040391 0.000498323 0.000221814 1ghz 0.01166646 0.00647035 0.00611162 0.007627428 0.003629156 3ghz 0.01846953 0.03341900 0.0102711 0.00463901 0.03693199 3.3.2.tan loss and ac conductivity tan loss variance is examined that ni0.3zn0.7prxfe2-xo4 (x=0.00, 0.025, 0.050, 0.075, and 0.1) nano ferrite is inversely proportional to the applied frequency. tangent loss reduced as frequency increased. the conduction phenomena was connected to electron hopping between fe2+ and fe3+ ions. since the applied and hopping frequencies were matched, the maximum loss occurred at a high frequency (junaid et al., 2016). the variance of tangent loss with frequency shows in the below figure 5(a). the most important properties of dielectric materials is ac conductivity. at room temperature, the ac conductivity of ni0.3zn0.7prxfe2-xo4(x=0.00, 0.025, 0.05, 0.075, and 0.1) synthesized nanoferrites was determined in frequency range is between 1 mhz and 3 ghz. the formula for calculating ac conductivity is as follows: σac = (t/a) z′/(z′2+z′′2) (13) from the above formula ‘t’ denotes pellet thickness, ‘a’ denotes area, z′ denotes the real impedance part, and z′′ denotes the imaginary impedance part. the figure 5(b) shows that, at lower frequency the ac conductivity of most samples have a growing pattern, but in the higher frequency region dispersive behavior of samples. according to the maxwell wagner theory, ferrites materials are composed of conducting grains separated by a resistive layer of grain boundaries. reduced porosity may also be causing the increase in conductivity behavior. conductivity has a grain boundary effect at low frequencies, while conducting effects of grains have been found at high frequencies, resulting in dispersion. because of the impacts of grains and the hopping phenomena in fe2+ and fe3+ at octahedral sites, conductivity improves at high frequencies. as the applied field increases, the charge journal of materials and physical sciences 1(2), 2020 105 carrier hopping frequency increases, resulting in an increase in ac conductivity (junaid et al., 2016; parveen et al., 2019). figure 5: (a) tangent loss vs frequency (b) ac conductivity vs frequency 3.4.4.real and imaginary impedance impedance analysis is a useful method for determining the relationship between dielectric properties and microstructural composition of synthesized materials. for each of the ferrite ni0.3zn0.7prxfe2-xo4(x=0.00, 0.025, 0.05, 0.075, and 0.1), the real and imaginary impedance parts was calculated, the real part of impedance as a function of log f is shown in figure 6 (a) and the imaginary part of impedance as a function of log f is shown in figure 6 (b). the following formulas are used to calculate the impedance of the real and imaginary parts. z' = r = |z|cosθz (14) z' = x = |z|sinθz (15) from the figures 6. (a) and (b), as the frequency rises, the real and imaginary parts of impedance decreases according to impedance analysis. as frequency increases, the impedance curves of all samples converged, and at higher frequencies, impedance shows constant behavior, which is attributed to the discharge of space charges. the concentration differential as well as the inhomogeneity of the applied field lead these charges to collect on grain boundaries, resulting in space charges. the real and imaginary impedance parts decrease as the field frequency increases, indicating that conductivity improves. h. m. noor ul huda khan asghar, muhammad kamran nawaz, rafaqat hussain, zaheer abbas gilani 106 figure 6: (a) real part of impedance vs log f and (b) imaginary part of impedance vs log f table 4 impedance and modulus for ni0.3zn0.7prxfe2-xo4 (x=0.00, 0.025, 0.050, 0.075 and 0.1) parameters frequency x =0.00 x = 0.025 x = 0.05 x = 0.075 x = 0.1 z' (ohm) 1mhz 1.71e+04 2.95e+04 2.81e+04 2.98e+04 3.57e+04 1ghz 4.96e+00 3.87e+00 3.41e+00 8.96e+00 1.67e+00 3ghz 9.54e-01 2.15e+00 6.57e-01 6.05e-01 2.08e+00 z'' (ohm) 1mhz 1.04e+05 4.10e+04 3.47e+04 2.87e+04 5.78e+04 1ghz 1.10e+02 1.31e+02 1.26e+02 1.83e+02 1.15e+02 3ghz 3.85e+01 4.29e+01 4.28e+01 6.11e+01 4.02e+01 m' 1mhz 0.2024545 0.0795422 0.0673809 0.0557857 0.1122099 1ghz 0.2152537 0.2554927 0.2468301 0.3579872 0.2239255 3ghz 0.2240875 0.2500398 0.2493514 0.3561609 0.233999 m'' 1mhz 0.0331216 0.0572957 0.0546066 0.0579428 0.069395828 1ghz 0.0096803 0.007555 0.0066595 0.0175114 0.003252934 3ghz 0.0055598 0.012549 0.0038269 0.0035259 0.012147948 3.4.5.real and imaginary electric modulus the electric modulus describes how grains and grain boundaries influence a materials dielectric properties. within a specific frequency range, the real (m') and imaginary (m") parts of electric modulus are calculated by the following relation: m' = ɛ' / ɛ'2+ɛ''2 (16) m'' = ɛ'' / ɛ'2+ɛ''2 (17) the m' and m" modulus of a prepared nanoferrites with the compositional formula ni0.3zn0.7prxfe2-xo4(x=0.00, 0.025, 0.05, 0.075, and 0.1) was measured of the applied frequency 1mhz to 3ghz ranges. electric modulus can be used to study the electrical reaction of ferroelectric materials, which is based on the phenomenon of electric complex modulus formalism can be used to describe grain and grain boundary effects in some homogeneous materials. the electric modulus of ni0.3zn0.7prxfe2-xo4 is utilized to analyze the effects of interfacial polarization as a function of applied field frequency. the real part of electric modulus (m′) is shown in the figure 7(a), and the imaginary part of electric modulus (m") is shown in figure 7(b). figure 7: (a) the real electric modulus as function of frequency (b) the imaginary electric modulus as function of frequency figure 7(a) depicts the variance of the real part of modulus (m′) with frequency. the value of m′ increases with the increase in frequency, as seen in the graph. this is because the materials have a space charge polarization effect. the value of m′ is increased then decreased at a certain frequency range of 1 mhz–3 ghz. now from the figure 7(b) show that the imaginary electric modulus (m'') decreased with frequency increased. the journal of materials and physical sciences 1(2), 2020 107 relationship between grain boundaries and peak formation confirms this perspective (ditta, khan, junaid, khalil, & warsi, 2017). 4. conclusions praseodymium (pr3+) doped nickel−zinc ferrite having general formula ni0.3zn0.7prxfe2-xo4 (x=0.00, 0.025, 0.050, 0.075 and 0.1) was synthesized via microemulsion technique, that is the easiest method to synthesizes of such type of ferrites. the fcc spinel structure is confirmed by xrd measurements. the xrd method was used to analyzed crystal structure and crystalline phase formation, and it’s a great way to find out crystalline parameters including crystalline size, lattice parameters, x-ray density, and bulk density etc. the most intense peak of the xrd was identified at 2θ=35º. from debye sherrer's formula, calculated the crystalline size 15nm to 29nm ranges. lattice constant in the range of 8.360å−8.380å. the lattice parameter calculations are decreased with the doping of praseodymium (pr3+) contents. fourier transform infrared spectroscopy (ftir) technique was used to investigate spinel crystal structure of the prepared sample of composition ni0.3zn0.7prxfe2-xo4 (x=0.00, 0.025, 0.050, 0.075 and 0.1). ftir analyses reveal two frequency stretching bands ʋ1 and ʋ2 that correspond to the tetrahedral and octahedral sites respectively. the absorption bands ʋ1 is known as octahedral stretching bands are found to be in the range of 414 cm-1 and ʋ2 is the tetrahedral stretching band are found to be in the range of 530cm-1. dielectric properties of praseodymium doped nickel zinc ferrite were measured with impedance analyzer from 1 mhz to 3 ghz frequency range. when pr3+ concentration increases, the dielectric characteristics, such as dielectric constant (ɛ') and dielectric loss (ɛ'') and tangent loss was found to be decreases. the electric modulus describes how grains and grain boundaries influence a material's dielectric properties. electric modulus can be used to study the electrical reaction of ferroelectric materials, which is based on the phenomenon of electric complex modulus formalism can be used to describe grain and grain boundary effects in some homogeneous materials. these measured dielectric characteristics showed that these nanomaterials may be used in higher frequencies devices. acknowledgement we are grateful to oric of balochistan university of information technology, engineering and management sciences (buitems), quetta pakistan. references ahmed, m., bishay, s. t., & radwan, f. 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(2017). new lini0. 5prxfe2− xo4 nanocrystallites: synthesis via low cost route for fabrication of smart advanced technological devices. ceramics international, 43(17), 14807-14812. https://doi.org/10.52131/jmps.2020.0101.0005 37 journal of materials and physical sciences volume 1, number 1, 2020, pages 37 47 journal homepage: https://journals.internationalrasd.org/index.php/jmps impact of ho and ce ions substitution on structural, electrical, and dielectric properties of ni-zn ferrites alina manzoor1*, aqib javed1, amir muhammad afzal2, m. imran arshad1, aamir shahzad1 1 department of physics, government college university, faisalabad, 38000, pakistan 2 department of physics, riphah international university, 13-km raiwind road, lahore-54000 pakistan article info abstract article history: received: may 14, 2020 revised: june 16, 2020 accepted: june 29, 2020 available online: june 30, 2020 in the present study, influence of holmium (ho) and cerium (ce) ions on the electromagnetic properties of ni0.67zn0.33fe1.9ho0.1-xcexo4 ferrites (x = 0, 0.025, 0.05, 0.075, 0.1) synthesized by the selfignited sol-gel method was studied. the xrd experiment was performed to determine the substitutional effects on structural parameters. ftir spectroscopy and i-v measurements were carried out to analyze the spectral and electrical behavior of substituted samples. x-ray diffraction patterns revealed the fcc structure of the prepared samples the value of average crystallite size was noticed between 25.89-39.51 nm, while lattice constant was found in the range 8.37-8.41 å. both the low and the high frequency absorption bands were confirmed by ftir technique. tetrahedral band was noted in the range 463-495 cm-1 while octahedral band was observed in range 558-560 cm-1. the dc resistivity was observed to decrease with increase in temperature which indicates the semi-conductor like behavior of the prepared samples. dielectric study showed that both the dielectric constant and the tangent loss factor were decreased with rise in the applied field frequency. keywords: xrd nanoparticles dc resistivity ftir spectroscopy dielectric properties © 2020 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: alinamanzoor@gmail.com 1. introduction the launch of nano-crystalline magnetic materials has opened up a new era in the history of magnetism. magnetic materials at the nanoscale are the foundation of the innovation of recent time. it is some of the time taken that the progressive accomplishments of today technology are truly not cell phones, satellite and space communication, or super-fast trains; it is essentially the capability to introduce those materials which are actually the fundamental parts for various technological and modern applications. the nano structured magnetic oxide materials now a days have become the center of interest due to their novel applications and noteworthy tremendous properties (hashim et al., 2012). nano-sized soft ferrites, among all the present magnetic materials have drawn the attention of today researchers for not only their flexible and testing uses in density recording media, microwave frequency based devices, and data processing strategies, yet likewise their rare and matchless properties, for example, redistribution of cations and super paramagnetism (spm) in contrast to their bulk matches (randhawa & singh, 2013). the cubic ferrites are found to be incredibly unique materials due to the extraordinary features such as superparamagnetic nature, extraordinary permeability, low magnetic losses, great thermo-chemical stability, low eddy losses, high dc resistivity, large saturation magnetization, and single area conduct which can be upgraded by tuning the material processing methods as well as the response conditions. all the above-mentioned https://journals.internationalrasd.org/index.php/jmps mailto:alinamanzoor@gmail.com alina manzoor, aqib javed, amir muhammad afzal, m. imran arshad, aamir shahzad 38 unique properties manage the cost of these materials in ultrahigh frequency applications that require strong connection to the electromagnetic signals while offering the minimal losses (dar, shah, siddiqui, & kotnala, 2012; ferrites, 2012). the surface properties perform a leading role as compared to core in managing the physical and chemical features of nano materials (alone, shirsath, kadam, & jadhav, 2011). for high-performance devices, a basic need is to manufacture the ferrite materials at nano scale. below a critical size, soft ferrites act like single-domain systems. the domain wall resonance effect is maintained at critical size, and material can offer high efficiency at higher frequencies (rao et al., 2006). soft ferrites also known as cubic ferrites possess a general formula mefe2o4, where ‘me’ can be a trivalent or a divalent ion. the cubic phase ni-zn cubic ferrite is among one of the notable and most substantial kinds of soft ferrites which possess large saturation magnetization (ms), high curie temperature, and high dc resistivity (akhter & hakim, 2010). one way to improve their electrical conductivity, structural, dielectric, and electromagnetic properties is to substitute rare earth cations (ho3+, la3+, er3+, ce3+, etc) on octahedral sites (cai, wang, et al., 2016; cai, xu, et al., 2016; iqbal, islam, ali, sadiq, & ali, 2014). secondly, a great deal of improvement has been believed to understand different synthetic and physical phenomenon associated with substituted ni-zn ferrites. the profoundly resistive ni-zn nano-ferrites alongside reasonable incorporation of trivalent, divalent, and rare earth (re) cations have discovered unique thought by various experts because of huge practical assorted variety of appropriately substituted ni-zn ferrites. as discussed earlier by a. ghafoor et al that dc electrical resistivity increased by doping of holmium ions, yet the saturation magnetization also reduced by 32 % and increase in coercivity was predicted. holmium (ho) and cerium (ce) being rare earth elements possess high electrical resistivity as well as large magnetic permeability (manzoor, khan, shahid, & warsi, 2017). here, in the present study, we expect to examine the substitutional effects of ce and ho ions into the ni-zn structure which has never been concentrated before. subsequently, to address the issue of low lose and highly resistive materials, we propose the ho and ce doped ni-zn ferrites via size-monitored sol-gel method. the current work is the study of ho and ce doped ni-zn ferrites to reveal the substitutional consequences for microstructure, cations redistribution, optical, electrical, and dielectric characteristics. remarkably, when ce and ho ions are introduced in nickel-based magnetic oxides, the substitute of fe by larger sized ce and ho ions differ the basic structural, spectral, electrical, and dielectric parameters. 2. experimental ni0.67zn0.33fe1.9ho0.1-xcexo4 (x = 0.00-0.1) nano-sized ferrites doped with ho and ce were prepared through a self-ignited sol-gel method. the stoichiometric volumes of ni(no3)2.6h2o, fe(no3)3.9h2o, zn(no3)2.6h2o, ho(no3)3.5h2o and ce(no3)3 were taken in distilled water. after a homogeneous mixing of all salts, citric acid was added at 40 ºc with salts to citric acid ratio of 1:2 subject to constant mixing. the addition of citric acid being a natural chelating agent can help to chelate the metal particles with alterable ionic dimensions and forestalling precipitation to protect the uniformity among the ingredients. next to that, precipitate formation was avoided by raising the ph of the solution by adding 2m ammonia solution. the solution was then heated at 90 ºc under constant stirring after which a thick gel was acquired. by raising temperature as far as 150 ºc, the auto-ignition of thick gel took place, and a furry dark gray material was obtained. after the well grinding of obtained material, the sintering was conducted at 900 ºc for 6 hr for the elimination of natural residues and for the formation of cubic phase. circular shaped pellets of 13.55 mm diameter were made below 30 kn pressure using hydraulic press. the xrd patterns of annealed samples were taken to examine the structural parameters and fcc phase confirmation by x-ray diffractometer (d8 advance-bruker) at room temperature. ftir spectra were taken from 400 -to 1000 cm-1 utilizing nickolet spectrometer (tm 5700) at room-temperature. room-temperature dielectric study was carried out on pellets samples utilizing wayne ker impedance analyzer (wk6500b) from 1 mhz -to 3 ghz. the dc resistivity was determined by two probe technique. journal of materials and physical sciences 1(1), 2020 39 3. results and discussion 3.1. x-ray diffraction analysis the recorded xrd scans of ni0.67zn0.33fe1.9ho0.1-xcexo4 (0.0≤ x ≤0.1) nano particles calcinated at 900 ºc are presented in figure 1. the presented xrd patterns revealed the brag diffractions of fcc structure relating to fd3m space group (asifiqbal et al., 2017). the xrd graph of the sample with x=0 shows the formation of fcc single phase with all necessary reflection peaks having hkl (220), (311), (400), and (511) as verified by icdd no: 00-010-0325. no extra peaks other than the fcc phase x=0.00 assured the formation of single-phase fcc structure. though, the substitution of ho and ce inside ni-zn lattice influences the spinel network and prompts the presence of an impurity phase (hofeo3) defined by icdd no: 00-010-0325. the broadening of reflection peaks is noted for samples with x ≥ 0.025. no traces of secondary phase are identified for x=0.1 and for the sample in which both holmium and cerium doping is absent. the diffraction peak (311) is found to be broaden by increasing the value of x. various structural quantities like lattice constant (a), porosity (p), cell volume (a3), and densities (hypothetical and mass) are affected by ho3+ and ce3+ contents. the lattice constant ‘a’ is calculated using nelson-relay function (ali et al., 2012) and its variation is plotted with respect ho and ce content in ni0.67zn0.33fe1.9ho0.1-xcexo4 ferrites. the lattice constant is examined to increase with the addition of ho and ce ions which is attributed to the larger ionic radii of ho and ce ions on octahedral sites. the average crystalline size is determined from the widening of the diffraction peaks by debye scherrer's formula. d = kλ/βcosθ (1) here, d represents the value of average crystalline size, which is measured in nm, β is fwhm measured in radians, k is some constant (= 0.94), θ is the bragg's angle and λ is the known wavelength. the average crystallite size value is observed from 39.51 -to 25.89 nm. the theoretical (ρb) and experimental density (ρx) are determined by the following equations. ρb = m/лr2h (2) ρx = 8m/na3 (3) here m is the atomic weight, n is the avogadro's number, a shows the lattice constant, m is the pellet’s mass, h is the thickness and r is the radius of the pellet. as it is clear from above equation that x-ray density relies upon the molecular weight and the lattice constant of the material, its value increases from 4.74 -to 6.33 g/cm3 with increasing the ho and ce concentrations. this pattern is normal as molecular weight of holmium (164) and ce (140) are higher than that of the iron (56). similarly, the bulk density ρb is raised from 2.64 -to 3.94 g/cm3 with ho and ce substitution. since the density value of the iron (7.87g/cm3) is less than the holmium (8.8 g/cm3) than so a denser structure is expected to form by increasing the ho ions. the values of x-ray density are bigger than the bulk density which might be credited to the pores formed during the calcination procedure what’s more of improved densification and grains development upon ho and cerium consolidation substitution (haque, huq, & hakim, 2008). the percentage porosity (p %) is calculated using ρx and ρb via following relation; p % = 100 (1 – ρb/ρx). the percent porosity is noted to reduce from 44.6 to 23.2 %, as the x-ray density has greater magnitudes than bulk density as well as the increase with ho and ce ions incorporation. the formation of orthophase (hofeo3) covered the inter-granular cavities which results in high compression, so a decline in p is assuming upon ce and ho substitution. figure 2 illustrates the change in lattice constant with respect to ho and ce concentration. alina manzoor, aqib javed, amir muhammad afzal, m. imran arshad, aamir shahzad 40 20 25 30 35 40 45 50 55 60 in te n s it y ( a .u ) 2 (degree) x=0 x=0.025 x=0.05 x=0.075 x=0.1 standard sample (220) (400) (511)(311) figure 1: combined xrd graphs of ni-zn soft ferrites -0.025 0.000 0.025 0.050 0.075 0.100 0.125 8.24 8.26 8.28 8.30 8.32 8.34 8.36 8.38 8.40 8.42 8.44 l a tt ic e c o n s ta n t (å ) concentration figure 2: graph between ho, ce concentration and lattice constant journal of materials and physical sciences 1(1), 2020 41 3.2. ftir studies the qualitative information regarding materials’ structure and local symmetry of crystalline solids is provided by infrared absorption spectroscopy. figure 3 represents the ftir scans for all ni0.67zn0.33fe1.9ho0.1-xcexo4 samples. the scan range is taken from 400 -to 1000 cm-1. the growth of the spinel phase is validated by the taken ftir spectra. two distinct intrinsic frequency peaks are observed in the defined range arising due to the vibrations of oxygen-bonds and metal-cations. the intrinsic band υ1 at relatively higher wave number (550 600 cm-1) represents the oxygen ions bond and octahedral metalcation vibrations, while intrinsic band υ2 at lower frequency (450 500 cm-1) show up the oxygen bond and tetrahedral metal-cation stretching vibrations (ramesh, rao, samatha, & rao, 2015). for x=0, the octahedral (υ1) and tetrahedral (υ2) vibrational groups are revealed at 600 cm-1 and 450 cm-1. the following relations can determine the force constants of octahedral and tetrahedral sites (ko & kt). ko = 0.94213 m (υ2)2/ (m + 32) (4) kt = 2(1/2) ko (υ1/υ2) (5) here 'm' is the atomic weight of the particular composition. 0 500 1000 1500 2000 2500 3000 3500 4000 4500 t ra n s m it ta n c e ( % ) wave number (cm -1 ) x=0.00 x=0.025 x=0.05 x=0.075 x=0.1 general sample figure 3: ftir spectra of ni0.67zn0.33fe1.9ho0.1-xcexo4 (x = 0.00-0.1) ferrites a reduction in ko and kt is observed up to x = 0.06 and after that their values increased with rising the ho3+ and ce3+ concentration. it is also seen that the behavior of force constant is in consistent with bond lengths (ra and rb) which is ascribed to the reality that less energy is needed to break down the longer bindings and the other way around (srivastava & srinivasan, 1982). 3.3. dielectric studies the dielectric properties of ni0.67zn0.33fe1.9ho0.1-xcexo4 (x=0.00-0.1) ferrites have been examined from 1mhz -to 3ghz. figure 4 shows the variation of dielectric constant (ε′) as a function of frequency at room-temperature. the dielectric constant exhibits high values alina manzoor, aqib javed, amir muhammad afzal, m. imran arshad, aamir shahzad 42 at shorter frequency and then reduces quickly by increasing the frequency. such type of conduction has additionally been seen in different reaction of ferrite frameworks when exposed to the applied electric field. this type of conduction is characterized as debye type conduction which occurs when the charge transporters go through the space-charge polarization impact as supported by the koop's theory. ferrite materials are viewed as conducting-grains partitioned by relatively thin grain-boundaries (more resistive than grains) (koops, 1951). in ferrites, the source of polarization predominantly originates from four essential procedures: interfacial, dipolar, electronic, and ionic polarizations. the reason of conduction in spinel ferrites is basically the electron jumping between fe2+ and fe3+ ionic states at octahedral sites. for low field region the electrons heap up at inner interfaces because of poor leading resistive grain boundaries and hence creating space-charge polarization (livingston, 1999). by enhancing the applied field, the path of electron movements turned around before accumulating at boundaries which diminishes the possibility of electrons to move at grain boundaries. henceforth, conduction phenomenon and dielectric permittivity observed to decrease (singh, agarwal, & sanghi, 2011). the undamped dipoles caused some resonance peaks at f ~ 2 ghz (harrop & campbell, 1968). the maximum in dielectric constant happens under the following situation. 1000 10000 100000 1000000 1e7 4.00e-011 5.00e-011 6.00e-011 7.00e-011 8.00e-011 9.00e-011 1.00e-010 1.10e-010 d ie le c tr ic c o n s ta n t(  ) frequency(hz) x=0.00 x=0.025 x=0.05 x=0.075 x=0.1 gen.sample figure 4: frequency vs dielectric constant of ni0.67zn0.33fe1.9ho0.1-xcexo4 (x = 0.000.1) ferrites ωmax τ = 1 (6) where τ is the relaxation time and ωmax is the angular frequency equal to 2лfmax. when the electron's bouncing rate approaches to the applied field rate then debye relaxation occurs, also called the ferrimagnetic resonance (ashiq, iqbal, & gul, 2011). the applied field frequency at which polarity shifting of ions takes place is named as natural frequency. when both the natural and applied field frequencies remunerate one another, maximum electrical energy is moved to oscillating ions following a rise in power dissipation. consequently, a resonance happens as can be seen by the resonance heights (zhou, li, & chen, 2010). the addition of ho3+ and ce3+ ions at octahedral sites decreases the fe3+ ions residing there, delivering an adjustment in polarization. by increasing cerium and holmium contents at octahedral sites, a drop in hoping movement of electrons take place which diminishes the agglomeration of electrons at the grain boundaries and, subsequently, hindering the growth of space-charge polarization. it can be realized from figure 4 that the variation of ε′ with ho3+ and ce3+ substitution isn't consistent. the ε′′ and ε′ have values from 0.17 -to 0.77 and 2.54 -to 4.0 respectively, while for x= 0.12 the greatest values of ε′ and ε′′ are noted. this kind of nonlinear change in dielectric constant with respect to substitutional ions has also been stated earlier (cai, xu, et al., 2016). there are various complicated parameters that influence the dielectric constant, such as electronic journal of materials and physical sciences 1(1), 2020 43 polarization, ionic polarization, conductance losses, orientation as well as interface polarization (fang, ye, zhang, & xie, 2005). the detected variation in dielectric constant may be supported in two aspects; after addition of ho3+ and ce3+ ions into spinel structure, the cations end up being progressively expanded and can form multi-dipoles with anions (o2-) to enhance the dipolar polarization (abbas, dixit, chatterjee, & goel, 2007). moreover, the addition of ho3+ and ce3+ has successfully strengthen the fe2+ → fe3+ shift to bring down the dielectric losses that results from the enhanced electron jumping. furthermore, as the ionic radius of ho3+ and ce3+ are sufficiently greater than fe3+ so the rise in lattice constant twists the lattice coming about an increment in the natural activity. thus, conduction losses (ε′′) have improved (meena, bhattachrya, & chatterjee, 2010). the variations of tan loss and impedance as a function of frequency are shown in figures 5 & 6, respectively. 1000 10000 100000 1000000 1e7 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 ta n  log f (hz) x=0.00 x=0.025 x=0.05 x=0.075 x=0.1 gen. sample figure 5: log f vs tangent loss of ni0.67zn0.33fe1.9ho0.1-xcexo4 (x = 0.00-0.1) ferrites 1000 10000 100000 1000000 1e7 -2.00e+007 0.00e+000 2.00e+007 4.00e+007 6.00e+007 8.00e+007 1.00e+008 1.20e+008 1.40e+008 1.60e+008 z ( o h m ) frequency(hz) x=0.00 x=0.025 x=0.05 x=0.075 x=0.1 gen. sample figure 6: frequency vs impedance of ni0.67zn0.33fe1.9ho0.1-xcexo4 (x = 0.00-0.1) ferrites alina manzoor, aqib javed, amir muhammad afzal, m. imran arshad, aamir shahzad 44 3.4. electrical properties it is notable that the electrical characteristics of soft ferrites are exceptionally sensitive to stoichiometric ratios and imperfections (e. rezlescu, rezlescu, popa, rezlescu, & pasnicu, 1997). the dc electrical resistivity variations of ni0.67zn0.33fe1.9ho0.1-xcexo4 (x=0.00-0.1) ferrites are appeared in fig. 7. it can be seen that resistivity is increased by substituting ho and ce contents instead of iron. the holmium and cerium ions try to fill the octahedral sites because of their higher ionic radii. consequently, the number of fe3+ ions diminish at octahedral positions which causes a structural distortion. because of ho3+ and ce3+ substitution at octahedral sites, the hoping rate of electrons exchange between fe2+ and fe3+ is decreased with the decline of fe3+ ions which are accountable factors for conduction process in ferrites. consequently, the electrical resistivity increases with the substitution of ho and ce ions. 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 10 20 30 40 50 60 70 l o g  ( o h m -c m ) 1000/t (k) x=0.00 x=0.025 x=0.05 x=0.075 x=0.1 ni0.67zn0.33fe2o4 figure 7: 1000/t vs log of resistivity of ni0.67zn0.33fe1.9ho0.1-xcexo4 (x = 0.00-0.1) ferrites the rise in resistivity may be attributed to the higher resistivity values of ho (221 x 10-6 ω-cm) when compared to that of fe (9.98x10-6ω-cm) (koops, 1951). temperaturedependent dc electrical resistivity plots of ni0.67zn0.33fe1.9ho0.1-xcexo4 ferrites are displayed in figure 8. each of the samples following the arrhenius condition ρ=ρoeδe/k b t envisages the semiconductor nature of the materials, where δe is the activation energy acquired from the straight fitting of arrhenius plots (sattar, el-sayed, el-shokrofy, & el-tabey, 2005). the more extreme incline of log of resistivity versus 1/t for each composition of ni0.67zn0.33fe1.9ho0.1-xcexo4 can be seen because of the thermally initiated portability of charge carriers, yet not to a thermally activated creation of these carriers (n. rezlescu, rezlescu, pasnicu, & craus, 1994). journal of materials and physical sciences 1(1), 2020 45 0.000 0.025 0.050 0.075 0.100 10 20 30 40 50 l o g o f re s is ti v it y ( o h m -c m ) concentration (x) 373k 473k 573k 673k 723k figure 8: concentration vs log (ρ) of ni0.67zn0.33fe1.9ho0.1-xcexo4 (x = 0.00-0.1) ferrites 4. conclusions in summary, ho and ce doped ni-zn ferrite materials have been fabricated via selfignited technique. xrd experiment confirmed the fcc spinel phase formation. a secondary phase observed from x= 0.025 to x = 0.1 due to the agglomeration of ho and ce ions at grain-boundaries. the lattice constant, x-ray, and bulk densities noticed to increase whereas porosity reduced with the increase in ho3+ and ce3+ contents in the spinel structure of ni-zn ferrites. ftir spectroscopy revealed a clear change in vibrational bands with the substitution of ho3+ and ce3+ ions. the higher ionic radii of holmium and cerium deformed the centro-symmetric cubic structure which subsequently affect the entire polarization. ac conductivity realized to increase up to x= 0.1 while dissipation losses observed to decrease up to x =0.1 while the dc electrical resistivity is also increased by the addition of holmium and cerium ions. references abbas, s., dixit, a., chatterjee, r., & goel, t. 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(2010). dielectric and magnetic properties of zno-doped cobalt ferrite. journal of ceramic processing research, 11(2), 263-272. https://doi.org/10.52131/jmps.2021.0201.0013 22 journal of materials and physical sciences volume 2, number 1, 2021, pages 22 32 journal homepage: https://journals.internationalrasd.org/index.php/jmps impact of lanthanum doping on the structural, electrical, and magnetic properties of bafe12o19 nano particles zaheer abbas gilani1, siraj ul islam1, h. m. noor ul huda khan asghar1*, rafaqat husssain1, furhaj ahmad shaikh1 1 department of physics, balochistan university of information technology, engineering & management sciences, quetta 87300, pakistan article info abstract article history: received: march 23, 2021 revised: may 07, 2021 accepted: june 28, 2021 available online: june 30, 2021 these ferrites had been considered very highly valuable electronic materials for many decades. the ferrite compounds have a hexagonal structure. nano structural and dielectric features for bafe12-xlaxo19 (0.00, 0.25.0.50, 0.75, 1.00) nano hexaferrite (nhfs) was studied present research. the ba nhf prepared via sol-gel technique. the single phase of barium nano hexaferrites of various sample was confirmed by xrd, the average crystalline size calculated in the range of 5 to 13nm. the lattice parameter lattice constant, x-ray density, bulk density, micro strain and lattice strain are the parameters of xrd which are also calculated. the different parameters of xrd also show the decreasing and increasing trend which is totally depend on the concentration. the hexagonal structure also confirmed by ftir. there are two frequency band are investigated which are υ1 and υ2 which are associated with tetrahedral stretching band and octahedral stretching band respectively. the different frequency band are calculated at different frequency like υ1= 500 to 540 and υ2= 413. the dielectric properties also measured in the frequency range from 1 mhz to 3 ghz. there are many others parameters are calculated in dielectric properties such as real and imaginary electric modulus, real and imaginary impedance, dielectric constant, dielectric loss and tangent loss. the parameters of dielectric also showing decreasing and increasing in trend. the real and imaginary impedance plot changes as when the frequency increases, the all the specimens converge on one another, and at a higher frequency, the impedance exhibits coherent nature, which is due to the discharge of space charges. keywords: barium hexa ferrite lanthanum nano crystallite ferrites xrd ftir dielectric properties © 2021 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: noorulhudakhan@gmail.com 1. introduction in today's environment, magnetic materials are critical components of technology. humans have recognized the relevance of ferrites for many years by researching their many characteristics (smit & wijn, 1959). the improvement and development of ferrites is mostly dependent on the advancement and development of methods. different characteristics of ferrites, such as magnetization, electrical conductivity and permittivity, and dielectric losses, can be controlled by chemical composition, annealing, and doped metal ions (alhilli, li, & kassim, 2012; gilani et al., 2015). the magnetic and electrical characteristics of barium hexa ferrite are the most well-known. such materials are ideally suited due to their strong electrical resistance capabilities. they are widely used in the manufacture of microwave devices. because of their wide range of applications, barium hexaferrites are https://journals.internationalrasd.org/index.php/jmps mailto:noorulhudakhan@gmail.com zaheer abbas gilani, siraj ul islam, h. m. noor ul huda khan asghar, rafaqat husssain, furhaj ahmad shaikh 23 important magnetic materials. these materials are synthesized in a variety of ways due to their ease of manufacture, low cost, and high chemical stability (hussain et al., 2011). solgel technique is used to make these ferrites (garcia, bilovol, & socolovsky, 2012). with the use of a standard doping procedure, the dynamic characteristics of these ferrites may be adjusted to meet the requirements. doping a suitable element in a certain proportion can have a significant impact on the materials' remarkable characteristics (smit & wijn, 1959). the material's crystal structure determines its different characteristics. the characteristics and crystal structure of ferrites are used to classify them. different ferrites, such as spinel, garnet, and hexaferrites, have different structures that range from simple to complicated (carter & norton, 2007). the crystal phase of balaxfe12-xo19, according to the researchers, is a single m-type hexagonal phase. it is important to understand the material's structure in order to examine its characteristics. it is extremely difficult to examine a material's characteristics without first learning about its crystal structure (cullity, 1978). the x-ray diffraction study of the compositions balaxfe12-xo19 (x = 0, 0.25, 0.50, 0.75, 1.00) is addressed in detail in this work. in a straightforward manner, the entire method of indexing and computing different relevant structural characteristics is presented. this understanding will allow for a more exact examination of other materials' diffraction patterns. the ferrites behave like an inhomogeneous dielectric material made up of strongly conducting grains separated by an air gap or insulating layers known as grain boundaries. the dielectric constant, tangent loss, ac conductivity, and impedance of ferrite may all be modified by annealing and composition (sheikh et al., 2019). x-ray diffraction (xrd), fourier transform infrared spectroscopy (ftir), and dielectric characteristics analyses are used to analyze the prepared ferrite material. 2. experimental the production of different compositions of la doped bafe12o19 was done using the sol-gel auto-combustion process. to make the series of samples with the general formula balaxfe12-xo19 (x = 0, 0.25, 0.50, 0.75, 1.00), stoichiometric amounts of analytical grade reagents, such as barium nitrate (99%), iron (iii) nitrate (98%), lanthanum (iii) nitrate (99%), and citric acid (99.5%), were weighed using a precise digital balance. these metal nitrates and citric acid (which was used as a fuel) were dissolved separately in de-ionized water, then combined to produce the mixed solution. the magnetic pill (stirrer) was inserted into the solution, and the beaker was set on a hot plate. the solution was stirred, and the hotplate temperature was progressively increased to 150oc. for around 1 hour, the sample was stirred and agitated until the gel was produced. the temperature of the sample was raised to 300 oc as the gel was produced. when the gel was begun to burn, it was heated at this temperature for around 1 hour. it was let to burn regularly. it took around 1hour for the sample to completely burn. various gases were emitted from the beaker throughout this time. the final result was a dry powder that was homogeneous. the temperature of the hotplate was progressively reduced once the sample had completely burned. the hotplate was turned off after 10 minutes, and the specimen was allowed to cool in normal temperatures. despite the fact that the material is now in powder form, this was mixed thoroughly using a pestle and mortar. the sample bottle was filled with fine powder. the samples were all made in the same manner. in a muffle furnace, the samples were placed at 700°c for 3 hours. the samples were pelletized with a 4.5-ton pressure by using hydraulic press. the crystal structure of the produced samples was determined using the diffraction pattern obtained from x-ray diffraction (xrd). the xrd was performed using a panalytical expert pro to study the crystal structure and determine various crystalline structural characteristics. the range of values for 2 was specified to be between 10°and 80°. to examine tetrahedral and octahedral stretching bands, ftir analysis was performed. to study the dielectric characteristics of produced ferrite material, an impedance analyzer was used to conduct a dielectric analysis. several dielectric characteristics, including as the dielectric constant, dielectric loss, tangent loss, ac conductivity, real and imaginary impedance, and modulus, are computed in the frequency range of 1-mhz to 3-ghz, and their changes are investigated as doping increases. journal of materials and physical sciences 2(1), 2021 24 3. result and discussion 3.1. xrd analysis sol gel auto combustion is used to make barium hexa ferrites with the general chemical formula balaxfe12-xo19 (x = 0.0, 0.25, 0.50, 0.75, and 1.00). powder xrd is used on the panalytical expert pro to analyse the crystalline structure in detail and detect the crystalline phase formation. using this information, the first job is to identify the crystal structure of the sample. it's far more difficult to figure out the crystal structure of an unknown substance than it is to figure out the structure of a recognized one. the pattern of diffracted lines in a diffraction pattern reveals the crystal structure, the placements of lines reveal the unit cell, and the intensities of the lines reveal the positions of the atoms (cullity, 1978). the initial step is to identify this structure, which will provide information on the crystal structure in which the material is found. for this, the sin2 values for all main diffraction lines are computed. these values serve as a foundation for resolving the pattern. if certain diffraction lines appear owing to imperfections in the material or for other reasons, it causes issues and necessitates the use of additional talents. combining the plane-spacing equation with bragg's law equation yields a relationship that specifies the miller indices of a given crystal system. for a hexagonal system, for example, this formula may be expressed as sin2= a(h2+hk+k2)+cl2 (1) in this relation, a = λ 2 /3a 2 ) and c = (λ 2 /4c 2 ). value of a can be calculated from hkl (l=0). the x ray diffraction pattern of all concentrations of la+3 dopant have been analyzed, all x – ray diffraction values have been observed and shown on the basis of a jcpds card (reference no 00-027-1029), which shows us a values such as (106), (107) (200) (205) (1110) (300) and (220) at different planes. the values ranged from concentration to concentration, and with the addition of la +3, the value of v increases response to the different ionic radii of the la+3 and iron. the lattice distortion changed as lanthanum was doped in hexa ferrite. by the substitution of rare earth metal in hexa ferrites the also change were identified in the lattice parameter a and c (azim, atiq, riaz, & naseem, 2014). figure 1: xrd analysis of balaxfe12-xo19 (x = 0.0, 0.25, 0.50, 0.75, and 1.00). the crystalline size is determined using debye sherrer's formula for the hkl value of (107) d =kλ/βcos (2) zaheer abbas gilani, siraj ul islam, h. m. noor ul huda khan asghar, rafaqat husssain, furhaj ahmad shaikh 25 from above equation d represent crystal size, λ shows the wavelength which have the value 1.54a°, where k is also another constant which have fixed value 0.89a°, where β shows the full width half maximum. where theta is used for the most intense peaks. the crystal size of the current material doped with rare earth metal ranges from 13.37 nm to 5.84 nm, as shown in table 1, it tells us about the crystal size in which the trend is regularly decreasing down to 5 nm. the change in curve totally depend on ionic radii of the present material (fe+3) and the doped materials lanthanum (la+3) (onreabroy, papato, rujijanagul, pengpat, & tunkasiri, 2012). the following formula is used to calculate the lattice constant a and c sin2=a (h2+hk+k2) + cl2 (3) where a=λ2/ 3 a2 and c= λ2 / 4c2 first, the standards of the lattice constant "a" range from 5.83 ao to 5.90 ao which are shown in table 1, with different concentrations, it gives different rising and decreasing patterns. the variations are caused by the varying radii of the ions la+3 and fe+3. as a result, the lattice parameter c has also giving a rising and decreasing pattern based on concentration, as shown in table. the ups and downs in the lattice constant trend was caused by the ionic radii of lanthanum and iron, which are in different ranges for “a” and “c” respectively 5.83å to 5.90å and 23.1å to 23.85å. a particularly fluctuating pattern are because of divergence between ionic radii of accessible and subbed material in fixation. the following expression was used to calculate the x-ray density. x =2m/nav (4) since one-unit cell contains two molecules of the substance, 'm' was its molar concentration of the associated substance, multiplying by '2'. the frequency of avogadro's number is 6.02 1023, and it is denoted by the letter 'na.' and the volume of the unit cell is denoted by 'v.' table values show an improvement in the x-ray density of the relevant hexa ferrite doped with rare earth material, with the cause being an increase in the molecular weight of the substance doped with different amounts. the trend showing the increasing with the concentration level.as we know the molecular weight of iron is 55.84 g/mol and the lanthanum 138.9055 g/mol (azim et al., 2014; hussain & maqsood, 2008). the bulk density was calculated by the following formula = m/πr2h (5) given equation, m indicates mass, r represents the pellet radius in disk shape, h represents the sample's height. the bulk density of all samples have measured, this discovered the rate increases as the lanthanum concentration increases.it also show some decreasing in trend due to ionic radii. table 1 calculated different parameters of xrd of balaxfe12-x o19 (x= 0.00, 0.25, 0.50, 0.75, 1.00) parameters x=0.00 x=0.25 x=0.50 x=0.75 x=1.00 crystalline size (nm) 13.379936 12.193954 5.840577 6.1512175 6.3740861 lattice constant a (å) 5.839255 5.889154 5.841297 5.90298 5.884243 lattice constant c (å) 23.82 23.11 23.28 23.1 23.81 cell volume 199.10048 204.24843 199.30943 205.69035 203.73788 x-ray density (gc/m3) 73.494036 76.802935 76.320313 80.182300 80.826302 bulk density (gc/m3) 2.1084849 2.501271 2.5638718 2.4333474 2.2706820 lattice strain was calculated by the following formula which is commonly known as stokes wilson formula, mathematically this formula is written as lattice strain = ɛ = β cos / 4tan( )10-3 (6) journal of materials and physical sciences 2(1), 2021 26 where ɛ show the lattice strain and the here β was known as fwhm. micro strain was calculated by the following formula, mathematically this formula is written as micro strain = β cos/4 10-3 (7) the following mathematical expression was used to calculate the staking fault of balaxfe12-xo19 (x= 0.00, 0.25, 0.50, 0.75, 1.00). staking fault (sf) = 2π2/45/ √3tan ( ) (8) the dislocation density was calculated by the following mathematical expression δ= 1/d2 1015 lines /meter (9) the lattice strain, micro strain, dislocation density and staking fault trend increasing and decreasing at different level, which is depend upon the different concentration of rare earth metal lanthanum doped (azim et al., 2014). the notable values are shown in table 2. table 2 calculated different parameters of xrd of balaxfe12-xo19 (x=0.00, 0.25, 0.50, 0.75, 1.00) parameters x=0.00 x=0.25 x=0.50 x=0.75 x=1.00 lattice strain (10-3) 8.985351933 10.57688352 20.21259872 21.81314327 21.85618795 micro strain (10-3) lines-4/meter-4 2.551977734 2.973008241 5.732231212 6.114914363 6.154438432 dislocation density 1015 lines /meter 5.546924942 7.528193161 27.98632845 31.84778893 32.26081915 staking fault 0.464850958 0.467477582 0.465223769 0.468159456 0.467024478 3.2. ftir the ftir confirms the formation of hexagonal phases of different compositions. ftir spectra of balaxfe12-xo19 (x=0.0, 0.25, 0.50, 0.75, and 1.00) with various la+3 ion compositions (x=0.0, 0.25, 0.50, 0.75, and 1). there are two frequency bands widths are tracked. from fig 2 the two frequency bands are ranged as υ2 =413 cm-1 and υ1 =525537cm-1.υ1 the large frequency (almost 510 -550) cm-1 due to the inherent absorption bands at the tetrahedral site, and the other is at low frequency range υ2 ( 390-430) cm-1 due to octahedral extending bands (sheikh et al., 2019). all of the characteristic peaks in fig 2 can be attributed to m-type barium hexa ferrite. the values of υ1 change to a higher wave number as the la3+ ion content rises, and this can be assigned to the m-type barium ferrite. the values of υ1 change to a greater wavelength as the la3+ ion level increased, and this can be explained by two main realities. the first is that la+3 ions have a lower atomic weight than fe3+ ions, and the second is that even the atomic weight is inversely proportional to the wave number (el-sayed, meaz, amer, & el shersaby, 2013). the gap in bond length of fe3+– o-2 at tetrahedral and octahedral sites induced a shift in the intensity of the absorption bands, i.e. ‘υ1' and ‘υ2'. all of the prepared nanoparticle sets reveal that as the lanthanum concentration increased, the frequency band changes significantly, which may be attributed to grain size and lattice parameters (shahzadi et al., 2020). furthermore, using the bandwidth knowledge, the force coefficients kt and ko for octahedral and tetrahedral locales are calculated using the formula below. ko = 0.942128m (υ 2)2/ (m+32) (10) kt =√2ko υ 1/ υ 2 (11) where m shows the atomic weight of material, where υ1 and υ2 are different frequency. we investigate the constant force to improve the fixation, which demonstrates the conceivable reinforcing of bonding between. zaheer abbas gilani, siraj ul islam, h. m. noor ul huda khan asghar, rafaqat husssain, furhaj ahmad shaikh 27 figure 2: ftir spectra of balaxf12-x o19 the tetrahedral and octahedral radii are likewise gotten from the accompanying equations. r tetra = 𝑎√3( u−0.25 )−ro (12) rocta = 𝑎( 5 / 8−u ) −ro (13) where rtetra (tetrahedral radii) and rocta (octahedral radii), also u and “a” are different parameter, in above equation “a” is known as lattice parameter and oxygen position parameter is u (sheikh et al., 2019). table 3 the measured parameters for ftir parameters x = 0.0 x = 0.25 x = 0.50 x = 0.75 x = 1.00 molecular weight 1111.47 1132.2363 1153.0025 1173.7688 1194.535 υ1 / cm −1 530 525 532 536 537 υ2 / cm −1 413 413 413 413 413 ko(dyne/cm 2)×105 1.56201 1.56281 1.56358 1.56433 1.56505 kt/(dyne/cm 2) ×105 2.83481 2.80951 2.84838 2.87117 2.87785 3.3. dielectric properties the dielectric properties of synthesized ferrite materials with a basic equation of balaxfe12-xo19 (x = 0.0, 0.25, 0.50, 0.75, and 1.00) are measured at room temperature using lcr meter over a frequency range of 1 mhz to 3 ghz. dielectric properties of m-type hexa-ferrites for the substitution of rare earth metal are studied as the function of frequency at encompassing temperature. 3.3.1.dielectric constant and dielectric loss the graph between permittivity vs frequency is shown below. the dielectric constant has been measured experimentally by using formula given below. ɛʹ =c × d / a×ɛ (14) journal of materials and physical sciences 2(1), 2021 28 figures 3 display the variance of dielectric constant vs frequency for balaxfe12-xo19 ferrites (x = 0.00, 0.25, 0.50, 0.75, 1.00) at room temperature. the statistics demonstrate that as the fig 2 display the variance of dielectric constant, dielectric loss vs frequency for balaxfe12-xo19 ferrites (x = 0.00, 0.25, 0.50, 0.75, 1.00) at room temperature. this were discovered that the electrical interchange among fe2+ and fe3+ causes neighborhood movement, which determine polarization. the plots demonstrate that equally real and imaginary components of dielectric constants indicate frequency scattering. the dielectric constant, dielectric loss values are low at low frequency but instead quickly increases as frequency increases along with frequency of whole structures, indicating a basic pattern for every ferrite sample, this action reflects dispersion. according to koop's phenomenological theory, this behavior portrays dispersion caused by maxwell wagner type interfacial polarization (iqbal, islam, ali, sadiq, & ali, 2014). figure 3: (a) the dielectric constant as a function frequency (b) the dielectric loss as function of frequency 3.3.2.tangent loss and ac conductivity the graph clearly shows the tan loss goes down with growing frequency. the electrons follow the field when the frequency of the given alternating current of field of force is even lower compare the hopping frequency of ions among fe2+ and fe3+ electrons at neighboring octahedral sites, the ions obey the area thus loss was greatest. (tan loss) is high at high frequency and rapidly increase at high frequency, according to koop's phenomenological theorem. as a result, tan loss in the low frequency region is expected to be high, while tan loss in the high frequency region is expected to be high (iqbal et al., 2014). table 4 dielectric parameters for balaxfe12-xo19 parameters frequency x = 0.0 x = 0.25 x = 0.50 x = 0.75 x = 1.00 dielectric constant 1mhz 5.22376 4.16556 4.44576 5.41444 5.0067 1ghz 5.159 4.21558 4.60433 5.02073 4.75967 2.5ghz 4.49196 4.09188 5.56372 4.94024 4.45486 3ghz 4.27519 3.60566 4.25219 4.41541 4.52102 dielectric loss 1mhz 0.30928 0.38993 -0.05495 -0.33232 0.0531 1ghz -0.02137 0.14784 0.00664 0.07233 0.22985 2.5ghz 1.57008 0.3185 1.31588 0.23878 0.8102 3ghz 0.1106 -0.01209 0.38168 0.21544 0.40735 tan loss 1mhz 0.05921 0.09361 -0.01236 -0.06138 0.01061 1ghz -0.00414 0.03507 0.00144 0.01441 0.04829 2.5ghz 0.34953 0.07784 0.23651 0.04833 0.18187 3ghz 0.02951 0.00163 0.09316 0.05468 0.09635 about 1 mhz and 3 ghz, the ac conductivity of the prepared ferrite sample balaxfe12-xo19 (x = 0.0, 0.25, 0.50, 0.75, 1.00) is measured. the expression to be utilized zaheer abbas gilani, siraj ul islam, h. m. noor ul huda khan asghar, rafaqat husssain, furhaj ahmad shaikh 29 σ ac = (t ∕ a) × [zʹ/(zʹ2 + zʺ2 )] (15) where “t” shows that the thickness of pellet, area of the pellet is known as a, fig 5 illustrates the frequency-dependent alternating current conductivity of all sintered material. the ac conductivity with all samples start to increases from low frequency range, but dispersion conducting was observed at higher frequencies. ferrite substance are made up of transmitting grains isolated by conductive small sections of grain borders, according to both the maxwell–wagner model and the koop’s conceptual principle. since dielectric distortion is related to absorption processes. because of growing resistance of crystal structure the activity of all composition seems to be the same at low frequency (parveen et al., 2019). figure 4: (a) tangent loss as a function of frequency (b) ac conductivity as a function of frequency 3.3.3.real and imaginary impedance impedance is important in deciding the dielectric possessions of materials. the real and imaginary impedances are strongly directly proportional to the frequency. fig 6 represent the impedance as a role of the frequency, which ranges between 1 mhz and 3 ghz. the real and imaginary impedance portions of impedance are measured as for each ferrite balaxfe12-xo19 (x = 0.0, 0.25, 0.50, 0.75, 1.00),. by using the following formula to calculate the real and imaginary impedance. zʹ = r = | z| cos z, (16) zʺ = x = | z| sin z, (17) according to impedance analysis, the rise of the frequency at which it is used eliminates the real and imaginary sections of impedance. the impedance plot changes as when the frequency increases, the all the specimens converge on one another, and at a higher frequency, the impedance exhibits coherent nature, which is due to the discharge of space charges. the decrease in real and imaginary impedance components means that conductivity improves as field frequency increases, owing to the concentration difference and the non-uniformity of the given field, which tends to add these distinct charges on the crystal structure. above are both the imaginary and real impedance diagram. journal of materials and physical sciences 2(1), 2021 30 figure 6: (a) the real impedance as a function with log of frequency (b) the imaginary impedance as function with log of frequency 3.3.4.real and imaginary electric modulus modulus structures were being utilized to investigate the position of grain boundaries over a defined frequency spectrum. under the given frequency, the imaginary and real modulus of samples is investigated. the following are the formulas for calculating real and imaginary modulus. mʹ = ɛʹ/(ɛʹ2+ɛʺ) (18) mʹʺ = ɛʹʹ/(ɛʹ2+ɛʺ) (19) figures 7 demonstrate the real and imaginary electric modulus. at short frequencies, the real and imaginary components of the electric modulus have very small rates and rise sequentially as the given field frequency rises, while at large frequencies, they reach their limit (3 ghz) (parveen et al., 2019).the electrical modulus of balaxfe12-xo19 ferrites, which induced electrically charged concentration across the inorganic nanoparticles in expelling stimulation peaks, is used to investigate the frequency response of the concentration polarization impact. the sample of impedance with zʺ vs zʹ provides a better representation of the concentric spheres in the plane if the region of accuracy of the grain boundary is reduced. if the crystal structure region covers a great volume, the trend for modulus mʺ vs mʹ provides huge data about the semicircle. figure 7: (a) real electric modulus as a function of frequency (b) imaginary electric modulus as a function of frequency zaheer abbas gilani, siraj ul islam, h. m. noor ul huda khan asghar, rafaqat husssain, furhaj ahmad shaikh 31 table 5 ac conductivity, impedance, modulus for balaxfe12-xo19 (x=0.00, 0.25, 0.50, 0.75, 1.00) parameters frequency x=0.00 x=0.25 x=0.50 x=0.75 x=1.00 ac conductivity 1 mhz 4.4444e-05 1.336e-05 6.119e-06 6.5352e-06 5.62068e-06 1 ghz 0.00221902 0.0123562 0.000939 0.00582268 0.019071805 2.5 ghz 0.34628092 0.0683428 0.282689 0.0482143 0.16648189 zʹ (ohms) 1 mhz 82209147.0 14892846 1504486. 1666936.62 1430707.84 1 ghz 0.15416373 8.7130111 0.038683 1.15298201 14.4860242 2.5 ghz 114.489572 7.4630427 55.06665 2.15162838 32.3932633 zʺ(ohms ) 1 mhz 618646744 88370979 61590350 606886338 653764098 1 ghz 5436.83400 7331.8375 6432.649 5665.38172 6117.66131 2.5 ghz 834.987484 1221.1404 751.5586 932.680606 1018.09238 mʹ 1 mhz 0.1424188 0.1702161 0.1421027 0.1410586 0.1464052 1 ghz 0.1342679 0.1559214 0.1460475 0.137061 0.1424269 2.5 ghz 0.1310757 0.1585131 0.1243551 0.1385316 0.1447358 mʺ 1 mhz 0.0164175 0.0069877 0.002221 0.0023378 0.00216581 1 ghz 0.000715 0.0053751 0.0003581 0.0019553 0.00693064 2.5 ghz 0.0485361 0.012392 0.033661 0.0066537 0.02581722 4. conclusion from decades, these ferrites were regarded as extremely useful electrical materials. the ferrite compounds have a hexagonal structure, but there is also a category of ferrites called hexaferrites that have a hexagonal crystal structure. nano structural and dielectric features for bafe12-xlaxo19 (0.00, 0.25.0.50, 0.75, 1.00) nano hexaferrite (nhfs) was studied present research. the ba nhf prepared via sol-gel technique. the sol gel process is used to efficiently synthesize nano crystalline ferrite with the structural formula balaxfe12-xo19 (x=0.00, 0.25, 0.50, 0.75, 1.00).sol gel technique is very easy method to synthesized that type of ferrite. with their sharp peak, xrd studies affirm the hexagonal structure. the debye scherer expression is used to measure crystalline size, which is observed to be in the nano size range of 13 nm to 5 nm. the lattice constant also calculated by using the hkl with respect to the present materials jcpds card. the values of the lattice constant “a” in range from 5.83 å to 5.90 å, as with different concentrations, it gives different rising and decreasing patterns. the values of the lattice constant “c” in range from 23.10 å to 23.83 å, as with different concentrations, it gives different rising and decreasing patterns due to ionic radii. the crystal size pattern shows the decreasing order in crystal size. the ftir confirms the formation of hexagonal phases of different compositions. ftir findings indicate two stretching frequency bands corresponding to octahedral and tetrahedral, which are typical bands of hexagonal ferrite. in the frequency range of 1 mhz to 3ghz. the two frequency υ2 =413 cm-1 and the other υ1 =525-537cm-1. υ1 is the large frequency (almost 510 -550) cm-1 due to the inherent absorption bands at the tetrahedral site, and the other is at low frequency range υ2 (390-430) cm-1 due to octahedral extending bands. dielectric experiments are carried out. dielectric experiments give the permittivity and permit loss increase as change with frequency. the real and imaginary impedance curves change as when the frequency increases, the all the specimens converge on one another, and at a higher frequency, the impedance exhibits coherent nature, which is due to the discharge of space charges. there are many others parameters are calculated in dielectric properties such as real and imaginary electric modulus, real and imaginary impedance, dielectric constant, dielectric loss and tangent loss. conflict of interest the authors declare that they have no conflict of interest. reference al-hilli, m. f., li, s., & kassim, k. s. 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(1959). ferrites, philips technical library. eindhoven, the netherlands, 278. https://doi.org/10.52131/jmps.2022.0302.0026 48 journal of materials and physical sciences volume 3, number 2, 2022, pages 48 58 journal homepage: https://journals.internationalrasd.org/index.php/jmps ion implantation in the form of layers: a novel method to surface properties muhammad ahsan shafique1*, z. zaheer1, s. sharif2, h. taskeen2, s. a. shah2, athar naeem akhtar1, g. murtaza1, ghulam farid3,4 1 centre for advanced studies in physics, government college university lahore, pakistan 2 department of physics, forman christian college university (fccu), lahore, pakistan 3 department of applied physics, university of barcelona, c/martí i franquès, 1, 08028 barcelona, catalunya, spain 4 enphocamat group, institute of nanoscience and nanotechnology (in2ub), university of barcelona, c/martí i franquès, 1, 08028 barcelona, catalunya, spain article info abstract article history: received: july 25, 2022 revised: august 29, 2022 accepted: december 29, 2022 available online: december 31, 2022 in this study, a novel method was adopted to tailor the surface properties of iron. we attempted to increase the degradation rate of iron by h-induced damaging. equal number of h ions were implanted in four samples using a 2mv pelletron accelerator. but the ion distribution was varied in the iron matrix by adding h ion layers in successively increasing depths. interesting outcomes, contrary to our assumption were observed. the open-circuit potential was observed to shift toward a stable side. the tefal plot also revealed improved corrosion potential and decreased corrosion current by adding h layers. crystallographic studies revealed improved crystallinity and a small shift in preferred orientation of crystal growth. keywords: surface modification hydrogen ion implantation particle accelerator h layers © 2022 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: muhammadahsan@gcu.edu.pk 1. introduction the importance of iron is well-known and it is being employed in various engineering applications due to superior mechanical properties, appropriate corrosion resistance at a wide range of ph, and availability at a cheaper cost(mcneill & edwards, 2001; nishikata, ichihara, hayashi, & tsuru, 1997). although the use of pure iron is limited due to stability issues because some applications demand extended stability and lesser density to strength ratio. therefore, iron has been replaced by other materials like aluminum, magnesium, stainless steel and other alloys in various fields of applications. but this material is still being used in a large number of applications and the material scientists have always been working to counter its associated problems and to improve its properties for various applications. the hydrogen being smallest in the periodic table has a degree of freedom to diffuse into the lattice of almost every material even at a lower temperature(alefeld, 1078). the diffused hydrogen tends to accumulate at some local position in host lattice and they cause micro-cracks by weakening the chemical bonds. the micro-cracks are formed due to the formation of gas bubbles, however, the nature of the produced gas bubbles depends upon the host material. the trapped bubble in host matrix exerts pressure on grain boundaries, pushing them away from each other(song & curtin, 2012; xu & zhang, 2017). this phenomenon leads to metal failure called hydrogen-induced embrittlement. hede (hydrogen enhanced de-cohesion) is another phenomenon which leads to crystal failure in a specific direction (cleavage). the failure is due to an accumulation of h atoms within certain regions of a crystal system, the accumulated h atoms tend to reduce cohesive forces of crystal lattice(du et al., 2011). help (hydrogen enhanced localized plasticity) is a similar h https://journals.internationalrasd.org/index.php/jmps mailto:muhammadahsan@gcu.edu.pk muhammad ahsan shafique, z. zaheer, s. sharif, h. taskeen, s. a. shah, athar naeem akhtar, g. murtaza 49 induced failure. in this case, the h atoms reduce the crystal resistance to dislocation motion(myers et al., 1992). several methods are being applied to make the metals susceptible to hydrogen embrittlement. the hydrogen embrittlement hinders the use of several metals in different applications(han, xue, fu, & zhang, 2019). corrosion is a similar phenomenon that eventually causes material failure. unlike hydrogen embrittlement corrosion is a surface process. the surface atoms undergo unwanted chemical reactions with environmental species which leads to the formation of an oxide layer. the layer makes the surface passive to some extent. the corrosion phenomenon eventually causes material failure by weakening chemical bonds, loss of strength, and fatigue. electrochemical corrosion is another associated problem with iron which makes the iron lesser suitable for various application. iron is also an important biodegradable biomedical material because of biocompatibility, biocorrodibility and suitable mechanical properties (hermawan, alamdari, mantovani, & dubé, 2008; li, zheng, & qin, 2014; moravej & mantovani, 2011). this material is also being studied for bio-resorbable orthopedic, cardiovascular implant and tissue engineering scaffold applications. the degradation rate of a biodegradable implant is important for clinical application. the material degradation rate should be synchronized to the healing process, and material should degrade after a specific time. therefore, there should be some available techniques which could be employed to engineer the degradation rate of implant material. researchers are trying different techniques for the purpose. huang et al(huang, zheng, & han, 2016) observed enhanced the degradation rate of pure iron by zinc ion implantation. abdul hakeem et al proposed degradation rate can be tailored by incorporating biodegradable polymer into porous iron(yusop, daud, nur, kadir, & hermawan, 2015). wang et al also performed a similar study to enhance bio-corrosion, they found the incorporation of calcium silicate particles in the iron matrix to enhance the degradability(wang et al., 2017). waksman et al carried out an in-vivo study to investigate the compatibility of iron stents. they implanted bio-corrodible iron stents and cobaltchromium stents randomly in coronary arteries of pigs. they found no adverse effects of bio-resorbable stents(waksman, pakala, baffour, seaborn, & hellinga, 2008). in our study, we attempted to accelerate the degradation rate of iron by the deteriorating effects of hydrogen. we implanted hydrogen ions into the lattice of pure iron in a novel way. we observed the results contrary to our assumption, the hydrogen implanted iron samples are found even more stable as compared to the samples with no hydrogen content. interesting degradation behavior of pure iron is observed by changing the number of h layers in the iron matrix. our study suggests the hydrogen layers formation with the appropriate number density of hydrogen atoms in the metallic matrix could reduce the degradation rate of hydrogen-induced cavities. moreover, layers formation could be an effective technique to modify different surface properties. 2. experimental work 2.1. sample preparation five iron pieces having dimension 1.3cm×1cm and thickness 0.5 cm are cut from a sheet with the help of diamond wheel cutter. the samples are then grinded and polished using silicon carbide papers of different grits and diamond paste respectively. finally, the samples are cleaned in ultrasonic bath in deionized water and then in acetone for 15 minute each. 2.2. h ion implantation ions are implanted at the same energy =300 kev in a single layer (ion density =2×1014ions/cm2). the same dose is given to the second sample but one half of the dose (ion density in the first layer =1×1014ions/cm2) is implanted at 300 kev and the other half (ion density in second layer =1×1014ions/cm2) is implanted at 350 kev which makes two ionic layers in the iron matrix. the number density of each layer becomes 1×1014ions/cm2. similarly, in the third sample, the same dose is divided into three parts. three layers are journal of materials and physical sciences 3(2), 2022 50 formed, the first ion layer is implanted at 300 kev, the second layer is implanted at 350 kev and the third layer at 400 kev (each layer contains 0.66×1014 ion/cm2). likewise, four layers are formed in the fourth sample, the detail of energy, range of ions and number density is mentioned in table1”. we believe that the layers formation in the material lattice by varying ion distribution keeping the sum constant is a new technique. in our experiment the number density of h ions per unit area of the target is decreased sequentially. by adding the energy steps different layers of h are formed in the iron matrix. the ion ranges are estimated using srim simulation (ziegler, ziegler, & biersack, 2010). the different range profiles at different energies are given in table1 (a). table 1 ion distribution in different layers and projected ranges of ions at different energy steps (srim calculations) samples number of ion implanted (ion/cm2) energy steps (kev) projected range(µm) untreated 0 0 0 one layer sample 2×1014 300 1.32 two layer sample (1 +1)×1014=2×1014 300+350 1.32+1.58 three layer sample (0.66 +0.66 +0.66)×1014 = 2×1014 300+350+400 1.32+1.58+1.85 four layer sample (0.5+0.5+0.5+0.5)×1014=2×1014 300+350+400 +450 1.32+1.58+1.85 +2.14 table1 (a) srim simulation profiles at different energies (h ion concentrations in different depths) samples first layer e= 300 kev second layer e= 350 kev third layer e= 400 kev fourth layer e= 450 kev untreat ed one layer sample 2×1014 ion/cm2 twolayer sample 1×1014 ion/cm2 1×1014 ion/cm2 three layer sample 0.66×1014 ion/cm2 0.66×1014 ion/cm2 0.66×10 14 ion/cm2 muhammad ahsan shafique, z. zaheer, s. sharif, h. taskeen, s. a. shah, athar naeem akhtar, g. murtaza 51 four layer sample 0.5×1014 ion/cm2 0.5×1014 ion/cm2 0.5×10 14 ion/cm2 0.5×10 14 ion/cm2 2.3. ion dose calculation dose/sec = (beam current× number of charges in 1 coulomb) ÷ beam size dose= [(i×6.3×1018) ÷beam size] × time of exposure 3. characterization techniques “the xrd analysis is carried out using panalytic xpert pro diffractometer. cu kα(1.541ao) radiations are used at 40kv and 30ma for structural analysis. the diffraction profiles are recorded in glancing incident mode in 2θ range from 200 to 800 with a step size of 0.020 and total 3000 points are taken for each sample. gamry potentiostat (1000e) is used for electrochemical studies of samples. the potentiostat contains a three-electrode cell setup, the prepared samples are used as working electrodes. ag/agcl is used as reference electrode and graphite is used as counter electrode. all the electrochemical measurements are carried out at 35oc in ringer lactate solution. scanning electron microscope (sem) jeol jsm 6480lv is used in sei mode (accelerating voltage=20kv) for topographic studies of samples”. 4. results and discussion 4.1. xrd studies the xrd analysis is performed to investigate the impact of ion implantation on various crystallographic parameters by h ion implantation. the x-ray probe depth is estimated using the software xpert high score plus with mac calculator. the penetration depth is found 5.1 µm. the xrd profiles are shown in fig1. the signature diffraction peaks of fe [110] and [200] are observed at 2θ position approximately equal to 44.560 and 65.4040 respectively. the profile suggests that the preferred orientation of growth is [110] direction. the addition of the number of h layers increases the intensity of [110] peak while the intensity of [200] plane decreases. the maximum intensity of [200] plane is observed in as received sample (≈18.65%) while the minimum [200] peak intensity is observed in the sample implanted with 4 h ion layers (≈4.0%). this suggests that h ions in fe lattice encourage rearrangement of crystal lattice. this is also visible in the texture coefficient profile fig2. the alteration in the preferred orientation of growth is due to the energy distribution in the crystal lattice. the energy of incoming h ions dissipates in the lattice, allowing the grains to rearrange. during the rearrangement process, the grains tend to settle at the minimum energy position by changing the angle with respect to the previous position. a similar reason for the rearrangement of crystal planes is the decreased crystallite size. the surface of the grain boundary possesses some free energy due to unsatisfied bonds at the boundary. a greater number of grains per unit volume results in a larger number of grain boundaries. therefore, to attain equilibrium position the grains tend to rearrange. the peak broadening is not observed in xrd profiles. this indicates that the h ion does not trigger randomness or amorphization in iron lattice. the deeper penetration of h ions requires greater energy to overcome the coulomb barrier of electronic cloud and nuclear potential. journal of materials and physical sciences 3(2), 2022 52 30 40 50 60 70 0 200 400 600 0 200 400 600 0 200 400 600 0 200 400 600 0 200 400 600 30 40 50 60 70 2 theta control one layer two layers three layers four layers figure 1: xrd profiles of samples treated with different h layers the energy of incoming h ion dissipates in target lattice by multiple factors; in primary collisions with target nuclei, to overcome the electrostatic potential of electrons and protons. the primary collision mobilizes the target nuclei which perform further collisions with neighboring nuclei called secondary collision. the phenomenon results in a quasiunstable local region which is at a higher energy state. the energy in the region allows the lattice to relax and rearrange. akshaya et al (behera, facsko, bandyopadyay, das, & chatterjee, 2014) working in lower energy (50 kev) regime found amorphization by nitrogen ion implantation at lower fluence (1015 ions/cm2) and remarkable crystallization at higher fluence (1016 ions/cm2). rafique et al (rafique, butt, & ahmad, 2017) reported greater peak intensity by h ion implantation in zircaloy-4. naguib et al working in lower energy range 2-35 kev (naguib & kelly, 1970) found crystallization in amorphous zro2 substrates by kr implantation. makinson et al (j d. makinson, 2000) studied the diffraction patterns from the defects containing crystals by a computational technique. they concluded that the presence of point defects in crystal lattice decreases the peak intensity. muhammad ahsan shafique, z. zaheer, s. sharif, h. taskeen, s. a. shah, athar naeem akhtar, g. murtaza 53 0 1 2 3 4 0.80 0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 te xt ur e co ef fic ie nt (1 10 ) layers texture coefficient(110) 0 1 2 3 4 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 te xt ur e co ef fic ie nt (2 00 ) layers texture coefficient(200) figure 2: variation in texture coefficient of (110) and (200) planes versus no of h layers 0 1 2 3 4 -0.30 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 st ra in layers figure 3(a): variation in strain versus h layers 0 1 2 3 4 8 10 12 14 16 18 20 cr ys te lli te s iz e no of h layers figure 3(b): variation in crystallite size versus h layers lesser energy of incoming ions allows the energy distribution and localized annealing in a smaller region. increasing ion energy in different steps allows the energy distribution in a greater region of the target material. the crystallite size as a function of h ion penetration depth is mentioned in fig3 (b). the profile suggests that the crystallite size decreases by increasing the depth of implanted h ions. the smaller crystallite size is representative of the presence of imperfection in the lattice. the size of h ions is very small as compared to the volume of the unit cell or the size of atoms in host lattice, therefore, it does not change the volume of cell or cell distortion consequently imparting no strain as shown in fig3(a). there is no peak shifting as well which reveal h implantation has mild effects on the shape and size of the unit cell. the decreased crystallite size is attributed to the impact of accumulated h ions at grain boundaries. 4.2. electrochemical study 4.2.1.initial open circuit potential (ocp) the electrochemical studies are performed to predict the stability of fabricated samples in the ringer lactate solution. ocp profiles of treated and controlled samples is given in fig4. ocp value determines the initial stability of the samples; greater the ocp value stable will be the material. the ocp value of untreated samples lies in the middle of the figure. the ocp value shifts toward negative side by adding the entire h ion dose in a single layer. this is least stable sample it has a minimum ocp value (≈-0.40v). the initial ocp dramatically increases (shift to a lesser negative value) by adding a second layer of h+ in the iron lattice, in this case, the ion dose is same but divided into two regions by adding an energy step. journal of materials and physical sciences 3(2), 2022 54 0 200 400 600 800 1000 -0.44 -0.40 -0.36 -0.32 -0.28 -0.24 -0.20 -0.16 -0.12 o c p (m v ) time (sec) control sample one layer two layers three layers four layers figure 4: variation in open circuit potential of different samples with time 10 -7 10 -6 10 -5 10 -4 10 -3 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 po te nt ia l v sc e log current density (a/cm 2 ) control+four layers one layer two layers three layers figure 5: tefal plots of treated and untreated samples 0 1 2 3 4 0.0 1.0x10 -5 2.0x10 -5 3.0x10 -5 4.0x10 -5 5.0x10 -5 6.0x10 -5 i c o r r (a /c m 2 ) no of h + layers dose=2*10 14 ions/cm 2 figure 5(a): variation in corrosion current with number of h layers sample0 sample1 sample sample3 sample4 sample5 0 5 10 15 20 25 c o r r o s io n r a te a b figure 5(b): variation in corrosion rate with number of h layers 1 2 3 4 2 3 4 5 6 7 8 c o r r o s io n p o te n ti a l no of layers dose=2*1014 ion/cm2 figure 5(c): variation in corrosion potential with h layers further addition of a third layer further increases the ocp value. this is the threshold after this addition of another layer cause, a dramatic decrease of initial ocp value to the middle of the profiles, approximately equal to the value of untreated samples (≈300mv). the graph of treated samples representing ocp versus no of layers at the same dose is shown in fig4. the sample implanted with three h+ layers is found to be the most stable sample, while the sample with one h+ is found most unstable samples(zhu et al., 2009). the improved stability is due to the formation of protective h layers in iron lattice. the prepared ion layers hinder lattice distortion by stopping atomic diffusion across the layer. xu et al restricted the hydrogen diffusion in the iron lattice by trapping hydrogen atoms in the vacancies produced by irradiation. they consequently observed suppressed hydrogen embrittlement(xu & zhang, 2017). muhammad ahsan shafique, z. zaheer, s. sharif, h. taskeen, s. a. shah, athar naeem akhtar, g. murtaza 55 in our study, the abrupt decrease in ocp is attributed to the high energy of incoming h ions (the fourth energy step 450 kev). for the four layers sample, the energy carried by incoming h ions for the formation of fourth layers is highest among all the other ion energies (450 kev). while dissipating this larger amount of energy the incoming ions perform a greater number of the primary collision before coming to rest. the greater primary collision yields more displaced atoms in the lattice, which perform more secondary collisions. a bigger collision cascade is formed. consequently, the bigger collision cascade disturbs other layers formed by lower energy h ions. 4.2.2.potentiodynamic polarization potentiodynamic polarization (pp) study is carried out to investigate corrosion kinetics parameters of controlled and treated samples. the potentiodynamic polarization profiles are shown in fig5. the corrosion parameters are calculated from pp profiles by tefal extrapolation, different parameters are listed in table2. corrosion current (icorr) is plotted against the number of layers in fig. icorr profile clearly indicates a decrease in corrosion rate by increasing the number of h layers without changing the ion dose. maximum corrosion current (icorr) is observed in the controlled sample suggesting the most unstable sample. the samples having two and three proton layers are the most stable samples among all the samples under study. then the trend changes as the sample with four layers come up with a higher value of icorr≈ 12.60×10-6 a/cm2. a similar profile is observed by plotting corrosion rate against proton layers in fig5 (b), which signifies layers formation by increasing ion energy induces surface stability. the surface stability increases up to energy limit of 400 kev, however, the surface stability decreases for 450 kev energy step, as the corrosion rate shift from 0.536 mpy to 5.762 mpy. the corrosion potential, corrosion current and corrosion rate studies are consistent with each other. implanted hydrogen ion gets trapped in the iron lattice at vacancy and/or interstitial position, which may lead to the formation of fe-h complexes. lv et al reported by a theoretical simulation that the hydrogen atoms are very stable in the iron lattice at the vacancy position(lv, zhang, zhang, & su, 2018). the locked hydrogen changes some mechanical properties of host lattice; it is reported the incorporation of h atom in iron produces stress, strain, brittleness, and hardness (hiroshi nakazawa, 2011). in single layer deposition, fe-h complexes are distributed within the smaller volume of the iron matrix, therefore the number density is greater in comparison to multiple layer samples. the greater number density tends to deteriorate and destabilize the crystal structure. evenly distributed fe-h complexes in larger volume lead to the formation of a stable ordered structure as seen in xrd patterns. another reason for enhanced stability may be the incorporation of h atoms at vacancy and/ or interstitial sites produces a protective layer. the protective layer hinders the further diffusion of h atoms as reported by xu (xu & zhang, 2017). in our study, multiple h layers yield multiple protective shields consequently enhanced stability. 4.3. sem studies sem studies are performed after electrochemical corrosion study of control and treated samples. the analysis is performed to investigate the surface morphologies after corrosion studies. the sem micrographs of untreated and treated samples are shown in fig6. the corrosion products and pits are visible on all the treated and untreated samples. the corrosion products form different morphologies on different samples. a spongelike morphology is observed in the untreated sample which is due to the rapid removal of gases from the surface as a result of corrosion. this signifies a higher corrosion rate in the untreated sample. the typical sponge shape morphology is not observed in any treated sample but the craters and dimples of different shapes and densities are observed which indicated pitting corrosion. typical shapes of the linear cracks are not seen in any micrograph which indicates there is no hydrogen-induced damage or hydrogen embrittlement. journal of materials and physical sciences 3(2), 2022 56 figure 6: sem micrograph of untreated and treated samples: fig 5a: untreated sample revealing sponge-like structures due to removal of gases during the corrosion process. fig 5b,5c, 5d,5e and 5f showing pores and corrosion products. the cracks are not observed in any micrograph conclusion h ions are made to reside within different depths of the iron matrix by giving them different energies. this form different proton-rich region. in the first sample, all the protons are implanted in a single region called a single layer, while in the second sample, the same ion dose is distributed in two different depths forming two proton layers. similarly, an equal sum of h ions is distributed in three and four layers. the varied number density of implanted h ions changes the orientation of crystal growth. the decreased crystallite size is attributed to the impact of accumulated h ions at grain boundaries. the improved corrosion potential and decreased corrosion current by adding h layers is observed using tefal plot. the electrochemical studies reveal decreased corrosion current, corrosion rate, and enhanced corrosion potential by changing the number of h ion layers, the study suggests the h layers serve as a protective shield to hinder material degradation. acknowledgment the authors are thankful to oric, gc university lahore for providing funding 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(2010). srim – the stopping and range of ions in matter (2010). nuclear instruments and methods in physics research section b: beam interactions with materials and atoms, 268(11), 1818-1823. doi:https://doi.org/10.1016/j.nimb.2010.02.091 https://doi.org/10.1016/j.msec.2008.12.019 https://doi.org/10.1016/j.nimb.2010.02.091 https://doi.org/10.52131/jmps.2023.0401.0032 9 journal of materials and physical sciences volume 4, number 1, 2023, pages 09 19 journal homepage: https://journals.internationalrasd.org/index.php/jmps impact of holmium and nickel substitution on y-type hexagonal ferrites synthesized via sol-gel method alina manzoor1*, aamir shahzad1, muhammad imran arshad1, amir muhammad afzal2, tauqir shinwari3*, muhammad yaqoob khan4 1 department of physics, government college university faisalabad, faisalabad-38000, pakistan 2 department of physics, riphah international university, 13-km raiwind road, lahore-54000, pakistan 3 institut für experimentalphysik, freie universität berlin, 14195 berlin, germany 4 department of physics, kohat university of science and technology, kohat-26000, khyber pakhtunkhwa, pakistan article info abstract article history: received: february 12, 2023 revised: march 28, 2023 accepted: april 05, 2023 available online: june 27, 2023 sol-gel auto combustion route is employed to fabricate y-type hexagonal ferrites ba2-xhoxsr2-yniyfe12o22(x = 0, 0.02, 0.04, 0.06, 0.08, 0.1 & y = 0, 0.1, 0.2, 0.3, 0.4, 0.5). all prepared samples are examined through xrd, sem, and dielectric characterization.the prepared samples were then sintered at 950 °c for 6 hours. tga analysis was carried out to find the estimated sintering temperature for the phase development. the xrd experiment was performed to determine the effect of substitution on structural parameters. xrd crystallite size was observed in the range of 5.5 – 19.79 nm. lattice constant (a) was found in the range 6.08 – 6.17 å, and that of c was found in the range 44.08 – 44.73 å. the averagegrain size value wasnoted to be around ~ 2μm as calculated through sem.through raman spectroscopy, six active modes (3e1g, 2a1g, and e2g) correspond to different vibrational modes of the prepared samples. lcr technique showed that the dielectric constant and the dissipation factor were decreased with increased frequency. a decrease in dielectric losses suggests these materials are for high-frequency applications. keywords: hexaferrites sol-gel xrd dielectric constant sem raman spectroscopy © 2023 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding authors’ email: alinamanzoor@hotmail.com, t.tauqir@fu-berlin.de 1. introduction in the competition of new creations, new technological materials have acquired much more courtesy due to their direct convenience, particularly in material science. hexagonal ferrites have attracted much attention since their discovery by philips in the 1950s(irfan, elahi, & shakoor, 2016).due to their extraordinary magnetic properties, ferrites are the most widely utilized materials. due to their high stability, electrical resistance, and ferromagnetism, these materials are frequently used in permanent magnets, magnetic recorders, memory chips, and microwave devices. the structure of different ferrites differs from each other due to their structure, like spinel ferrites, orthoferrites, garnets, and hexagonal ferrites(chen, wang, liu, jin, & wu, 2022; c.-h. wang et al., 2022). due to their low cost, ease of manufacture, and exceptional electrical, dielectric, and magnetic properties, hexa-ferrites have attracted much attention in the technological areas in recent decades(lan, zhao, gao, kou, & wu, 2021; narang & pubby, 2021). manufacturing factors, such as composition, doping type and amount, sintering temperature and time, etc., significantly impact the materials' performance. due to their use in multilayer chip inductors, microwave devices, and magnetic recording, they are currently regarded as materials in demand (houbi et al., 2021). based on their crystal structure and chemical makeup, these ferrites can be divided into six main categories: m, w, y, x, z, and u-type hexa-ferrites. these hexa-ferrites differ from each other. https://journals.internationalrasd.org/index.php/jmps mailto:alinamanzoor@hotmail.com mailto:t.tauqir@fu-berlin.de journal of materials and physical sciences4(1), 2023 10 the different super-positioned configurations of the r, s, and t building components in these hexaferrites distinguish them (ali et al., 2015). y-type hexa-ferrites are a composite of hexagonal barium m-type ferrite and cubic spinel ferrites, which are among these hexagonal ferrites.although they have a complicatedstructure, they have a hexagonal structure parallel to the c-axis(ali et al., 2014). as a result, y-type ferrites have a selfbiased magnetic field that is uniaxial anisotropic and normal to the c-axis. as a result, ytype ferrites have a self-biased uniaxial magnetic anisotropic field and an easy axis of magnetization that is normal to the c-axis. consequently, they have a preferred plane to align the saturation magnetization, which can be chosen as a plane of microwave devices(batool et al., 2022).hexa-ferrites are used in a high-density magnetic recording medium, which calls for materials that can be precisely controlled in terms of homogeneity, shape, and magnetic characteristics. finding the most significant creation conditions to obtain tiny particles for use in high-density magnetic recording media is essential. the sol-gel, the chemical co-precipitation, sol-gel, microemulsion, hydrothermal synthesis, and opposite micelle(irfan et al., 2016; jacobo, domingo-pascual, rodriguez-clemente, & blesa; kumazawa, maeda, & sada, 1995; pillai, kumar, & shah, 1992; zhong & ding, 1997). in the current study, doping with a relatively small amount of y2o3 significantly alters the morphological, dielectric, and magnetic characteristics of y-type hexa-ferrites.as mentioned earlier, the variation of the properties is appropriate for their applications in various electrical devices working for industrial and military applications.hexagonal ferrites have varied applications in multiple devices, such as high-density magnetic recording systems, microwave devices, frequency telecommunication devices, biomedical applications (like cellular imaging, hyperthermia, target drug delivery, etc.), and cores of inductors.since the sol-gel auto-combustion method is straightforward in composition and shape, it has been utilized to create homogeneous nano-crystallites of hexagonal ferrites(irfan et al., 2016). hexagonal ferrites give high permeability in rf (radio frequency). this feature founds numerous applications in devices like micro-inductors and antennas(liu et al., 2018). hard ferrites or hexagonal ferrites have found multiple applications in telecommunication technology. they can be made devices applicable to high-range electromagnetic wave devices, which is very important for distortion-free telecommunication (majeed et al., 2016). ferrites with different cationic substitutions at various sites are useful in industrial and technological applications. due to unique properties of hard ferrites such as less electro-conductivity than metallic ferrites, high permeability, high curie temperature (tc), high value of ms, high value of coercivity (hc), and high remanence after the magnetic field and low eddy current lose made them very effective in different industrial and technological applications (din et al., 2014). at room temperature, nickel is a very oxidation-resistant and ferromagnetic metal. because rare earth metals significantly affect the system's magnetic anisotropy, spinel ferrite is promising. holmium and nickel-substituted y-type hexagonal ferrites are y-type hexagonal ferrites in which part of the yttrium (y) ions in the crystal structure have been changed to holmium (ho) and nickel (ni) ions. hexa-ferrites have magnetic properties widely used in various applications, including magnetic storage devices, microwave devices, and permanent magnets(yang & wang, 2017). they are also referred to as hexagonal ferrites or ferrite magnets. holmium and nickel ions can be utilized to swap out yttrium ions, altering the properties of y-type hexagonal ferrites. adding extra magnetic moments to the crystal lattice caused by the substitution of holmium can change the material's magnetic characteristics(aslibeiki, 2014). nickel replacement may also impact the ferrite's magnetic and structural properties. 2. experimental procedure to synthesize ba2-xhoxsr2-yniyfe12o22hexagonal ferrites,the following extremely pure materials such as ni(no3)2.6h2o, fe(no3)3.9h2o, ho(no3)3.5h2o, ba(no3)2 and sr(no3)2 were used. for the preparation of the solution, deionized distilled water was used. holmium and nickel substituted y-type hexagonal ferrites with a nominal composition of ba2-xhoxsr2yniyfe12o22(x = 0, 0.02, 0.04, 0.06, 0.08, 0.1 and y = 0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared by sol-gel method. the prepared solutions were then stirred using a magnetic stirrer. after the stirring of all these solutions, all the solutions were then combined into a alina manzoor, aamir shahzad, m. imran arshad, amir m. afzal, tauqir shinwari, m. yaqoob khan 11 single beaker while keeping the stirring on. the stirring was kept on until the formation of a homogeneous solution. the ph of the solution was kept at seven by adding nh3 solution dropwise. after attaining the desired ph, the heat was turned on while keeping the stirring on. after 4 hours of heat treatment, the solution was converted into the xerogel; by further heating, the xerogel was then converted into the ash. the ash was then ground to make the fine powder. after that, the fine powders were sintered at 950 ℃ for 6 hours. after sintering, the samples were ground well in the mortar and pestle to make the fine powder. in the end, the prepared samples were poured into the append drops in powder form, and some of the material was used to make pellets using a hydraulic press to study dielectric and i-v characterizations. to check the required phase of hexagonal ferrites of the crystal structure of the prepared sample were identified by xrd. sem calculated the grain size of hexagonal ferrites. for the energy bandgap of all samples using uvvisible spectroscopy. to check the dielectric response of materials in the 1 khz-1mhz frequency range was observed with an impedance analyzer. 3. results and discussion 3.1. tga analysis thermo-gravimetric analysis (tga) is a method for determining how much a sample weighs changes to temperature or time. it is frequently used to examine the materials' moisture content, thermal stability, and decomposition behavior. figure 1 shows the tga curve of fabricated y-type hexagonal ferrites with chemical composition ba2sr2fe12o22. this approach helps one to track the sample's weight loss with the increase in temperature. about 3% weight loss was obtained at 67 ℃, indicating the water's dryness, which was physically absorbed by the sample. however, almost 3% weight loss was observed at 606 ℃, indicating organic compounds' oxidation decomposition. however, after 765℃, no noticeable change in the weight loss was observed, which ensures the beginning of hexagonal ferrite phase formation(ahmad et al., 2015). figure 1: temperature vs weight loss curve ofba2sr2fe12o22 journal of materials and physical sciences4(1), 2023 12 3.2. xrd analysis figure 2 shows the xrd patterns of the holmium and nickel-substituted y-type hexagonal ferrites withthe composition of (ba2-xhoxsr2-yniyfe12o22)with(x = 0-0.1 and y = 0-0.5) were prepared by sol-gel method.the xrd patterns confirm the hexagonal structure of holmium and nickel-doped y-type ferrites. phase examines investigations were made by comparing the obtained xrd patterns with jcpds data file no. 00-051-1879. all the peaks in xrd patterns were compared with the standard jcpds data.the diffraction peaks seen from these xrd patterns correspond to the different planes described as (110), (0114), (021), (2011), (0219),and (2113). it is determined from these miller indices that the fabricated material has a hexagonal structure(elahi, ahmad, ali, & rana, 2013). the main peak is observed at 𝜃 = 29.286°, and the crystallite size for this peak is calculated to be 26.8 nm. at the same time, the crystallite size of other peaks (0114), (021), (2011), (0219), and (2113)are also calculated and found to be 28.52 nm, 14.22 nm, 16.56 nm, and 12.87 nm, respectively. the average crystallite size is found to be 19.80 nm. from figure 2, it is clear that when the ho-ni concentration rises, the intensity of some peaks decreases (rezlescu, istrate, rezlescu, & luca, 1974). it is noted that there is no peak splitting. different parameters are calculatedusing xrd data, such as crystallite size, fwhm, lattice constants, etc. for all categories of hexagonal ferrites "c," axis is considered the major axis. large variations in lattice constant "c" are more well-known than in "a"(j. wang, ponton, & harris, 2006). the c/a ratio values also established the y-type hexagonal structure. the following scherrer's formula calculates the crystallite size: d = kλ βcosθ (1) here, d represents the crystalline size in nm,k is scherer constant, and its value is 0.94 for y-type hexagonal structure,λ gives the x-rays wavelength, β represents the fullwidth half maxima value of different peaks, andθ provides the bragg's angle. figure 1: xrd patterns of ba2-xhoxsr2-yniyfe12o22 ferrites the calculated crystallite size ranges from 5.67 to 52.04nm.as ho-ni concentrations increased, the performance decreased, as shown by the size of the crystallites. many investigators have found declining behavior caused by doping rare earth cations.ho ions segregation, which occurs close to the grain borders and inhibits the movement of grain boundaries, is the cause of this reduction(lassoued & li, 2020; pant, arora, kaur, kumar, & kumar, 2010).lattice constants (a, c) are calculated using the formula(ahmad et al., 2013). alina manzoor, aamir shahzad, m. imran arshad, amir m. afzal, tauqir shinwari, m. yaqoob khan 13 sin2θ = λ2 3a2 (h2 + hk + k2) + ( λ2 4c2 ) l2 (2) cell volume is found using the formula: 𝑉 = 𝑎2𝑐 sin 120° (3) the d-spacing is found using the following formula: dhkl= 𝜆 2 𝑠𝑖𝑛 𝜃 (4) the x-ray density is foundusing the formula: dx = 𝑍𝑀 𝑁𝐴𝑉 (5) the unit cell volume of the prepared samples indicates an increasing trend, which is in good agreement with increasing dopants concentrations in y-type hexa-ferrites. since lattice constants affect unit cell volume, a similar pattern is seen in both instances. the crystallite sizeranges from 5.67nm to 52.04nm. the range of lattice constants a and c is found to be 6.08-6.17å and 44.15-44.73 å,respectively.the cell volume ranges from 1411.13-1467.96 å3(table 1). table 1 xrd parameters of ba2-xhoxsr2-yniyfe12o22 y-typehexagonal ferrites concentration angle 2𝜽 (degree) miller indices (hkl) fwhm (radian) crystallite size d (nm) lattice constant a (å) lattice constant c (å) c/a ratio unit cell volume v (å𝟑) x= 0, y=0 29.30 110 0.299 26.812 6.08 44.08 7.25 1411.13 x= 0.02, y=0.1 29.08 110 1.543 52.045 6.14 44.52 7.25 14.53.48 x= 0.04, y=0.2 29.18 110 1.274 6.299 6.09 44.15 7.25 1418.02 x= 0.06, y=0.3 28.69 110 1.418 5.667 6.17 44.73 7.25 1474.76 x= 0.08, y=0.4 28.97 110 1.274 6.299 6.16 44.67 7.25 1467.96 x= 0.1, y=0.5 29.18 110 1.413 5.679 6.09 44.15 7.25 1418.02 3.3. dielectric analysis the dielectric properties of prepared materials are investigated to determine the effect of doping fluctuations in the dielectric parameters. electrostatic energy stored per unit volume is used to define the dielectric constant. figures 3 and 4 depict the variations in the dielectric constant (ɛʹ)and tangent loss(ɛʺ)for all samples at room temperature under a frequency range of 4 hz to 8 mhz.the dielectric constant calculates the electrostatic energy retained per unit volume per unit gradient. the relative speed of an electromagnetic signal moving through a substance is measured using its dielectric constant. the dielectric constant is calculated using: ε′ = 𝐶𝑝 𝐶𝑜 , whereco= 𝐴𝜖𝑜 𝑑. (6) where έ is the dielectric constant, cp is parallel capacitance, ϵo is the permittivity of free space, a is the area of the pellet, and d is the thickness of the pellet. figure 3 shows that the dielectric constant (ɛʹ) decreasesas the applied frequency increases. at much higher frequencies, it becomes frequency independent, which is the expected behavior of hexa-ferrites. based on koop's polarization theory and the maxwell-wagner model, which claims that dielectric ions and conductivity have the same origin root, charge carrier behavior, and hopping predictions between fe3+ and fe2+, this result is attributed to space charge polarization. the chemical composition, fabrication process, sintering conditions, particle size, cation distribution, and other factors all affect the dielectric characteristics of hexagonal ferrites. as a function of frequency at room temperature, the dielectric constant (ɛʹ) is shown in the figure. dielectric polarization can be produced in the externally applied electric field because of the dielectric constant of the materials. the dielectric constant value also estimates the journal of materials and physical sciences4(1), 2023 14 speed of em (electromagnetic) signals. the dependence of the dielectric constant of ho-ni substituted y-type hexagonal ferrites having composition ba2-xhoxsr2-yniyfe12o22 on the frequency in the range of (4hz-8ghz) can be shown in figure 3. the dielectric constant was found to be decreasing with an increase in the frequency. that can be due to the exchange of fe2+ and fe3+ ions. dispersion in the dielectric constant can be found due to the dipole's relaxation. due to the irregular distribution of oxygen ions at grain boundaries and grain during sintering, interfacial polarization can occur. the dielectric constant in the ferrites is caused by the reduction of the field by the polarization effect. the dielectric constant is also caused by the electric, dipole, and ionic polarization at higher frequencies. the dipole and ionic polarization are found to be dominating in the microwave (ghz), and radio (mhz) frequency ranges(yasmin et al., 2020). figure 2: frequency vs dielectric constant (ε′) at room temperature dielectric loss illustrates the conduction of electrical energy from an external electric field within a dielectric substance. dielectric losses (ɛʺ) at room temperature as a function of frequency can be observed in figure 4. the dielectric loss factor is calculated through the following given equation. ɛʺ= ɛʹ tan(δ) (7) where tan (δ) is represented as tangent loss, (ɛʹ) is the dielectric constant, and (ɛʺ) is known as dielectric loss. from the above equation, dielectric constant and dielectric loss are directly related. the dielectric loss reflects the same trend as the dielectric constant. this dispersion is caused by interfacial polarization in the maxwell-wagner model and koop's phenomenological theory. hexa-ferrites exhibit polarization because of the hopping of electrons between fe2+ and fe3+. high-resistance charge carriers encounter significant barriers at grain boundaries, leading to polarization. however, as the frequency of the applied electric field increases, the charge carriers fail to recognize the changing applied electric field, resulting in a polarization(jadhav, shirsath, toksha, shengule, & jadhav, 2008). the measurement of the dielectric loss in polarization regarding changing fields is lagged. the figure 4 gives the tan δ (dielectric loss factor) pattern to that of frequency. as predicted earlier, the peaks in this graph can be seen when the charge carrier's frequency becomes equal to that of the external electric field. this occurs due to the similarity of the ferrite conducting system and dielectric polarization. based on this hypothesis, a potential clarification of the peaks in the above plot can be made (ihsan ali, islam, awan, & ahmad, 2014). alina manzoor, aamir shahzad, m. imran arshad, amir m. afzal, tauqir shinwari, m. yaqoob khan 15 figure 3: frequency vs dielectric loss at room temperature 3.4. impedance spectroscopy standard impedance spectroscopy is used to examine the electrical properties of the samples, and it is carefully observed in terms of interfacial/electrode, grain, grain boundary, etc. the impedance technique records electrical responses at temperatures when a sinusoidal signal with a frequency of 1 khz to 8 mhz is applied. the change in the impedance to the frequency is shown in figure 5.the value of z (impedance) was found to be increasing with an increase in the ho and ni concentration in ba-sr hexagonal ferrites, which follows the dependence of ac conductivity on the composition. the increase in impedance gives rise to a decrease in ac conductivity. in comparison, the impedance decreases with an increase in frequency which causes an increase in the ac conductivity. the reduction in impedance and increase in ac conductivity with the increasing frequency gives the semiconducting behavior of the prepared samples(khan et al., 2022). figure 4: frequency vs impedance (z) at room temperature journal of materials and physical sciences4(1), 2023 16 3.5. sem analysis scanning electron microscopy (sem) is employed to disclose particle shape and morphology of the surface of synthesized y-type hexagonal ferrites ba2-xhoxsr2-yniyfe12o22. figure 6shows the determined sem images of the fabricated samples. the characteristic platelet-like structure of the grains, almost uniform particle dispersion, and high density are all visible in these micrographs. the grain size of the synthetic powders is assessed using the line intercept technique. the range of the determined grain size, which is between (0.83 μm–1.11 μm), is quite large. higher sintering or calcination temperatures are the cause of the big grain size. sem analysis of ba2sr2fe12o22 sem analysis of ba1.98ho0.02sr1.9ni0.1fe12o22 sem analysis of ba1.96ho0.04sr1.8ni0.2fe12o22 sem analysis of ba1.94ho0.06sr1.7ni0.3fe12o22 sem analysis of ba1.92ho0.08sr1.6ni0.4fe12o22 sem analysis of ba1.90ho0.1sr1.5ni0.5fe12o22 figure 5: sem analysis of ba2-xhoxsr2-yniyfe12o22 nano ferrites calcined at 950 °c for 6 h the analysis of the morphology of the grains of ho and ni substituted ba-sr hexagonal ferrites sintered at 950 ℃ for 6 hours was carried out vis sem in the above figures. the clustering of formed grains may be due to grown particles having large surface areas and may also be due to attractive forces between the magnetic particles(chauhan et al., 2018). the grain size was also found to be increasing with the substitution of ho and ni in the prepared samples. the grain morphology was found to be enhanced by the substitution of ho and ni in the ba-sr hexagonal ferrites. the grain size of the prepared samples was also calculated, and the average grain size was found to be 2µm. 3.6. raman analysis raman spectroscopy is an innovative, non-destructive spectroscopy material identification technique used to provide information about structures comparable to one another and structural problems. figure 7 shows the raman spectra of synthesizedba2xhoxsr2-yniyfe12o22 hexagonal ferrites (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1 & y = 0, 0.1, 0.2, 0.3, 0.4, 0.5) nanomaterials ranged from 150 to-800 cm-1. the raman spectra of hoand ni substituted ba-sr hexagonal ferrites are displayed in figure 7. out of 42 raman active modes (11a1g, 14e1g, 17e2g), six active raman modes are found, which corresponds to different vibrational modes (table 2). alina manzoor, aamir shahzad, m. imran arshad, amir m. afzal, tauqir shinwari, m. yaqoob khan 17 table 2 raman active modes of b2-xhoxsr2-yniyfe12o22 (x = 0-0.1 and y = 00.5) hexagonal ferrites concentration e1g (cm -1) e2g (cm -1) a1g (cm -1) e1g (cm -1) e1g (cm -1) a1g (cm -1) x= 0, y=0 193 329 462 514 617 685 x= 0.02, y=0.1 191 327 462 512 615 685 x= 0.04, y=0.2 199 318 462 518 611 674 x= 0.06, y=0.3 197 318 462 510 615 671 x= 0.08, y=0.4 195 327 462 516 617 685 x= 0.1, y=0.5 193 326 462 512 615 685 e1g mode is found to be in the range of 191-199 cm-1, which is designated as a vibrational mode of the whole spinel block because of e1g symmetry. e2g mode is found to be in the range of 318-329 cm-1, which is designated as the vibrational mode of the octahedral 2k site because of e2g symmetry. a1g mode is found to be 462 cm-1 due to the vibrational mode of octahedral 2k sites because of a1g symmetry. e1g mode is in the range of 510516 cm-1 due to the metal oxide bond vibration at the octahedral 2a and 2k sites because of e1g symmetry. a1g mode is in the range of 611617 cm-1 due to the stretching vibration of the fe-o bond at the 4f2 octahedralsite because of a1g symmetry. a1g mode is in the range of 671685 cm-1, due to the vibration mode of pyramidal 2b sites because of a1g symmetry that makes a difference between spinel and hexagonal structure(khalaf, abd ellateef, alnajjar, & mohamed, 2020). figure 7: raman spectra of b 2-xhoxsr2-yniyfe12o22 hexagonal ferrites at room temperature conclusion y-type hexagonal ferrites with compositionb2-xhoxsr2-yniyfe12o22 aresynthesized viasol–gel method followed by an auto-combustion.xrd experiment confirmed the formation of pure phased y-type hexagonal structure with no impurity traces. a significant raman active modes of ba2sr2fe12o22 raman active modes of ba1.98ho0.02sr1.9ni0.1fe12o22 raman active modes of ba1.96ho0.04sr1.8ni0.2fe12o22 raman active modes of ba1.94ho0.06sr1.7ni0.3fe12o22 raman active modes of ba1.92ho0.08sr1.6ni0.4fe12o22 raman active modes of ba1.90ho0.1sr1.5ni0.5fe12o22 journal of materials and physical sciences4(1), 2023 18 development was observed in the primary lattice parameter "c" axis. the crystalline size (5.67to 52.05 nm), lattice constant a(6.08 – 6.17 å), and that of c (44.08 – 44.73 å) displayed significant variation as a function of ho-ni concentration. sem study revealed an average grain sizeto be 2µm. the dielectric constant and dissipation factor decreased due to the fe2+ and fe3+ ions exchange. dispersion in the dielectric constant can be found due to the dipole’s relaxation.raman spectroscopy of ho-ni nano ferritesrevealed six active modes, namely (3e1g, 2a1g, and e2g), corresponding to different vibrational modes of the prepared samples. reference ahmad, m., ahmad, m., ali, i., ahmad, w., mustafa, g., akhtar, m. n., . . . abbas, g. 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(1997). mad zhmag, n.,". key step in synthesis of ultrafme bafel: o19 by sol-gel techniques'al magn. mag. mater, 168, 196. https://doi.org/10.52131/jmps.2021.0202.0020 95 journal of materials and physical sciences volume 2, number 2, 2021, pages 95 107 journal homepage: https://journals.internationalrasd.org/index.php/jmps experimental study of neodymium (nd3+) doped mn-ni based spinel ferrite (mn0.5ni0.5ndxfe2-xo4) nanoparticle using sol-gel method zaheer abbas gilani1, muhammad waqas tariq1, h. m. noor ul huda khan asghar1*, naeem khan1 1 department of physics, balochistan university of information technology, engineering & management sciences, quetta 87300, pakistan article info abstract article history: received: october 07, 2021 revised: december 11, 2021 accepted: december 30, 2021 available online: december 31, 2021 neodymium (nd3+) doped mn-ni based spinel ferrite with composition of mn0.5ni0.5ndxfe2-xo4 (x= 0.00, 0.5, 0.10, 0.15 and 0.20), the nanoparticle was essentially formulated by solgel self-ignition method. the impact of nd3+ doping on structural and electrical properties has been extensively studied. xrd verified the fcc spinel arrangement of the synthesized samples. the debye scherer formula is used to determine the crystalline size, which was observed in the nano scale ranging between 6 and 10 nm. xrd was used to validate the composition, crystalline size and determining different structural parameters of sample. it is noted that the lattice parameter changes when the nd3+ doping concentration was enhanced because smaller radius of fe3+ ions is replaced by large ionic radius of nd ions. when nd concentration raises xray density and dislocation density also rises. ftir verify the compositions of spinel phase and also examine the absorption bands. there were two major frequency bands one was high frequency band ν1 with range of about 500cm -1. second was low frequency band ν2 with range of about almost 400cm -1. dielectric performed in the frequency range of 1 mhz to 3 ghz. it was used to determine the effect of nd3+ doping on various parameters. dielectric investigations showed decline in dielectric constant. impedance analysis revealed reducing values with frequency, due to the increase in material conductivity. real and imaginary modulus study showed the influence of grain boundaries at low frequencies. these properties played significant role in high frequency applications and semiconductor devices. keywords: spinel ferrite neodymium nanocrystallite ferrites xrd sol-gel dielectric properties © 2021 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author: noorulhudakhan@gmail.com 1. introduction magnetic material which has both electrical and magnetic nature is known ferrite. the ferrite materials with iron oxide and metal oxide shows different and unique properties which are used in electrical, magnetic, electronic and electrochemical felids (chavan, babrekar, more, & jadhav, 2010; goldman, 2006). spinel ferrites are a class of oxide materials having an incredibly rare mix of electric and magnetic characteristics. spinel ferrite exhibit superb features like, high frequency, strangely high electrical resistance and high saturation magnetization (adam, davis, dionne, schloemann, & stitzer, 2002). nanocrytalline spinel ferrite (ncsf) show massive attraction due to their amazing physical and chemical properties related to bulk material. spinel ferrite nanoparticle are greatly important to scientists and researches due to their extraordinary applications, electronic produces microwave, television, home appliances, media recording radio and communication. more applications are in different field like medical diagnoses, magnetic https://journals.internationalrasd.org/index.php/jmps mailto:noorulhudakhan@gmail.com journal of materials and physical sciences 2(2), 2021 96 refrigeration, water purification and ferro-fluids (maaz, mumtaz, hasanain, & ceylan, 2007; song & zhang, 2004). to enhance magnetic and electrical properties of spinel ferrite the rare earth material has been doped because they have stable valency and large radius (roy & bera, 2006). basically mn and ni are soft magnetic material which have a lot of applications in different fields of life such as in electronic devices, transformator core, and high frequency applications (azadmanjiri, 2008; mathe & kamble, 2008). neodymium (nd3+) is doped with mn-ni based spinel ferrite which causes structural spoil and development of electrical magnetic properties and also rise density, electrical resistance, high eddy current and reduce the saturation magnezation and electrical loss because neodymium has unpaired electrons in outermost shell (4f orbit) which increase to iron with non-magnetic nature. neodymium ions have big ionic radii which replaces iron (fe) ion at octahedral site of ferrite, resulting in high-frequency application while improving the magnetic and electrical property of spinel ferrite (b. chauhan, kumar, jadhav, & singh, 2004; wang, chen, zeng, & hou, 2004). these characteristics of spinel ferrite depend on nature, type of dopants and also depend on synthesis method and placement of cations over the vacant interstitial sites (gilani, warsi, khan, et al., 2015). the objective of this article is to examine the effects of neodymium ion doping on structural, electric, dielectric properties and magnetic characteristics of mn-ni based spinel ferrites, as well as their suitability for transferring high frequency applications and memory storage devices. 2. experimental procedure mn-ni based spinel ferrite nanoparticles were prepared by sol-gel method using manganese (ii), nickel (ii) and neodymium (nd3+). the manganese nickel ferrite doping with rare earth element (nd3+) with different concentration (x= 0.00, 0.5, 0.10, 0.15, 0.20). the chemical material with analytical form was utilized as crude agent to prepare necessary ferrite nanomaterial. the substance contained nickel nitrate [ni (no₃)₂6h₂o], manganese nitrate [mn (no₃)₂·4h₂o], ferric nitrate [fe (no3)3.9h2o] and citric acid [c6h8o7.h2o] which were mixed in distilled water to achieve a homogeneous solution. the solution was placed on the hot plates at temperature 80oc with magnet stirrer at 400 rpm to dry until the sol was formed. after a while, sol transformed into a black high dense gel. the solution was regularly stirred and the hotplate the temperature began to raise steadily enhanced up 150oc. the gel burnt in response to the self-spreading exothermic oxidation reaction. the final product was obtained in the form of homogenous fluffy dry powder. the fine powder was then annealed for four hours at 600 degree celsius to produce the materials' hexagonal phase. after that the prepared samples were analyzed by using xrd analysis crystalline structures. it gives information about structures morphology, grain size, shape, strain and desired crystalline perspectives. the angle range of 2θ is form 100 to 800. ftir verify the compositions of spinel phase in each formulation and provides information about chemical variations and cation distribution. ftir spectra range was observed between (400-1000 cm-1). dielectric was used to determine the effect of nd3+ doping on various parameters such as the a.c conductivity, real and imaginary parts of the modulus, impedance, dielectric constant, electric modulus, and loss tangent was analyzed at frequencies ranging from 1 mhz to 3 ghz. 3. results and discussion 3.1. xrd analysis the sol-gel method was used to prepare xrd arrangement of mn0.5ni0.5ndxfe2-xo4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) spinel ferrites. the phase of crystallization of the specimens was annealed at 600°c for 4 hours. xrd was used to validate the composition and crystal size. the crystalline phase of the prepared specimen was verified by xrd measurements. xrd has really promising approach for determining different structural parameters of materials of various compositions, such as crystallite size, lattice strain, lattice constant, xray density, unit cell volume, bulk density, micro-strain, stacking fault and dislocation density (a. chauhan & chauhan, 2014). the xrd graph of all spinel ferrite samples are shown in fig 1. the data shows that at 2θ = 35∘, extremely intense peaks value with 311 hkl form, which is a great peak for spinel ferrites nano-particles. the peaks that are kept in contact with the xrd trend are recorded as (220), (311), (400), (331), (422), (333), (440) and (531). all of these peaks relate to fcc spinel structure peaks, indicating that the ferrite was made up of fcc spinel structure, as verified by jcpds card. according to the xrd study, all of the specimens have distinct sharp peaks. all of the reported peaks were wide, zaheer abbas gilani, muhammad waqas tariq, h. m. noor ul huda khan asghar, naeem khan 97 indicating that the ferrite was nanocrystalline. a pair of secondary peaks can be seen, one of which is at 2θ= 44.5 and has an hkl value of 411, and the other is at 2θ =32.9. these secondary peaks could be caused by nd insolubility in the octahedral location (gilani, warsi, anjum, et al., 2015). figure 1: xrd pattern of mn0.5ni0.5ndxfe2-xo4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) table 1 different structural parameters of mn0.5ni0.5ndxfe2-xo4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) parameter x=0.0 x=0.05 x=0.10 x=0.15 x=0.20 crystalline size(nm) 8.518 10.763 6.501 8.341 6.228 lattice constant 8.2862 8.2816 8.3300 8.3452 8.3246 cell volume 568.9495 568.0029 578.0189 581.1807 576.8996 bulk density 1.42203 1.54089 1.61890 1.431309 1.342516 x-ray density 5.41696 5.51954 5.53881 5.60011 5.75680 3.1.1.crystalline size vs concentration the average crystalline size of the formulated ferrite substance was calculated using xrd. the crystalline size was used to determine the hkl value of (311) by debye sherrer's equation dm=kλ/βcosθ (1) there k is the constant whose value is 0.9. λ representing the wavelength which is equal to 1.54ao, β represents the worth of the angle of an extreme peak with fwhm, and θ represents the angle of scattering of the most extreme peak. the crystalline size was calculated to become very small ranging between 6 and 10 nanometers. it was observed that the crystalline size differed in-homogeneously with the doping of nd3+. this crystalline size in-homogeneity possible that this is due to the creation of a impurity phase., as well as the comparatively small ionic radius of nd3+" relative to the fe" to be substituted (vijayabhaskar, rajmohan, vignesh, & venkatakrishnan, 2019). the crystalline size difference can be seen on the graph below. journal of materials and physical sciences 2(2), 2021 98 figure 2: crystalline size vs nd concentration mn0.5ni0.5ndxfe2-xo4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) 3.1.2.lattice constant vs concentration nelson relay method was used to determine the lattice parameter. a= d (h2+ k2+l2)1/2 (2) the average lattice constant was found between the range of 8.28 to 8.32 å. the foundation of nd3+ and fe3+ ion radius changes as the value of the “a” changes. it's important to note that the lattice parameter decreases when the nd3+ion substrate is doped. it's because the fe3+ ion's massive radius has been replaced (0.76 a) at the octahedral positions by small orbit of an nd ion.the lattice constant declines rapidly with doping at first, then increases, then decreases again. this may be expected for nd3+ ion separation at grain boundaries. the following graph depicts the difference in the lattice parameter. figure 3: lattice constant vs concentration mn0.5ni0.5ndxfe2-xo4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) zaheer abbas gilani, muhammad waqas tariq, h. m. noor ul huda khan asghar, naeem khan 99 3.1.3.x-ray density vs concentration the equation below can be used to measure the x-ray density of formulated spinel ferrite. dx=8m/na3 (3) here m indicates the sample's molecular weight, 8 denote the number of formulation units, n represents "avogadro's number" of 6.0223 x 1023, and “a” represents lattice constant. the difference of x-ray density with comparison to concentration ranges from 5.41 to 5.75 gm/cm3. the relationship between x-ray density and concentration is considered to be mostly static. when nd concentration raises x-ray density also raises, which is due to higher molar weight of nd3+ (144.242) relative to fe (55.845). a graph depicting the increases in x-ray density as a behavior of nd concentration is seen below. figure 4: x-ray density vs concentration mn0.5ni0.5ndxfe2-xo4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) 3.1.4.bulk density vs concentration bulk density of specimen was used to analyze the following equation, ρm= m/v (4) here “m” is mass and volume is denoted by ʻʻv”. bulk density varies between 1.34 and 1.61 gm/cm3.it is estimated to be much lower than x-ray density. the inhomogeneous variance of bulk density is noted; it raises first, then declines steadily with concentration (ortega-zúñiga et al., 2019). figure 5: bulk density vs concentration mn0.5ni0.5ndxfe2-xo4 (x = 0.00, 0.05, 0.10, 0.15 and 0.20) journal of materials and physical sciences 2(2), 2021 100 3.1.5.lattice strain vs concentration the stokes-wilson formula was used to measure the lattice strain of the synthesized nano-particles. ε = β/4 tan θ (10-3) (5) β shows the fwhm of intense peak. the lattice strain was estimated between 13.19 x 103 and 18.06 x 103. the lattice strain dropped at first, than enhanced, decrease and finally began to enhanced w.r.t the doping concentration. at the value of x = 0.20, the maximal value of lattice strain was observed (wu et al., 2019). the graph below depicts variations in lattice strain as a function of concentration: figure 6: lattice strain vs concentration mn0.5ni0.5ndxfe2-xo4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) 3.1.6.micro strain vs concentration the given equation calculates the micro-strain of the synthesized samples. micro-strain = (β cos θ)/4 (10−3) (6) the micro strain was calculated between the ranges 4.06 x 10-3 and 5.56 x 10-3. it was estimated to be rising in a discontinuous nature in relation to the doping concentration. the maximum possible value of micro-strain is identified at x = 0.20. the following graph depicts shifts in micro-strain w.r.t concentration. figure 7: micro-strain vs. concentration mn0.5ni0.5ndxfe2-xo4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) zaheer abbas gilani, muhammad waqas tariq, h. m. noor ul huda khan asghar, naeem khan 101 3.1.7.dislocation density vs concentration the dislocations density of formulated spinel ferrites is obtained by the following equation δ = 1/d2 (1015) (7) where d represents the crystalline size of sample. the dislocations density is obtained in the range from 13.78 x 1015 to 25.77 x 1015. it was noticed that dislocation density raised when the doping concentration of nd was enhanced. at x = 0.20 the maximum value of dislocation density was determined. graph of dislocation density is given below: figure 8: dislocation density vs. concentration mn0.5ni0.5ndxfe2-xo4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) 3.1.8.stacking fault vs concentration stacking fault equation is given below: stacking fault (sf) = 2π2/45√3 (tan θ) (8) initially a decrease was noticed in the stacking fault, it gradually increased up to some values(x=0.15) and then decreases once more. it's possible that the inhomogeneous behavior was caused by the temperature increase. this behavioral arrangement is depicted in the figure 9. figure 9: stacking fault vs concentration mn0.5ni0.5ndxfe2-xo4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) journal of materials and physical sciences 2(2), 2021 102 table 2 shows the different values of lattice strain, bulk density micro-strain and stacking fault 3.2. ftir ftir verifies the compositions of spinel phase in each formulation and provides information about chemical variations and cation distribution. the ftir verifying the spinel structure composition of sample was mn0.5 ni0.5 ndx fe2-x o4. there were two major frequency bands one was high frequency band ν1 with range of about 500cm-1 and second was low frequency band ν2 with range of almost 400cm-1. we investigated the tetrahedral and octahedral frequency bands. the absorption peaks also known as high frequency bands were caused by the tetrahedral site of internal metal spreading vibrations, whereas low frequency bands were caused by octahedral-metal stretching bands (mori, imazeki, tsutsui, & tanahashi, 2019). fig.10 exhibit ftir spectra range observed between (4001000 cm1) figure 10: ftir frequency bands of of mn0.5 ni0.5 ndx fe2-x o4 the fig. shows the bands of the spinel structure's characteristic. the variation in higher frequency band was found in the range of 532537 cm-1. however, lower frequency band were found to remain unchanged with range of about 413 cm-1. the stretching vibration of fe3+ _o2at tetrahedral and octahedral sites formed the higher frequency and lower frequency bands. the location of the band varies with the doping of nd3+. the change in the lattice parameter causes the ν1 frequency band shift a little bit to the high frequency. these variations affected the stretching vibration of fe3+ _o2and as a result, of band location can change. table 3 frequency bands of ftir mn0.5 ni0.5 ndx fe2-x 04 (x= 0.00, 0.5, 0.10, 0.15 and 0.20) s.no composition ν1/cm −1 ν2/cm −1 1 mn0.05 ni0.5 fe2 o4 534 413 2 mn0.05 ni0.5nd0.05fe1.95o4 536 413 3 mn0.05 ni0.5nd0.10fe1.90o4 534 413 4 mn0.05 ni0.5nd0.15fe1.85o4 537 413 5 mn0.05 ni0.5nd0.20fe1.80o4 532 413 parameter x=0.00 x=0.05 x=0.10 x=0.15 x=0.20 lattice strain 13.191457 10.4179588 17.316864 13.569587 18.069548 microstrain 4.0676247 3.21932616 5.329642 4.1537960 5.5627974 dislocation density 13.780826 8.63223949 23.658634 14.370896 25.773892 stacking fault 0.444369 0.44384172 0.444833 0.446163 0.444766 zaheer abbas gilani, muhammad waqas tariq, h. m. noor ul huda khan asghar, naeem khan 103 3.3. dielectric measurements the dielectric properties of arranged spinel ferrite samples with formulation of mn0.5 ni0.5 ndx fe2-x o4 (x= 0.0, 0.5, 0.10, 0.15, 0.20) was investigated using an impedance analyzer. dielectric properties of fabricated spinel ferrites are identified at frequencies ranging from 1 mhz to 3 ghz. these properties play a significant role and are essential due to their uses in high frequency products. these characteristics are extremely dependent on the ways used for the preparation of the material's configuration and cations position (bibi et al., 2018). various dielectric parameters are mentioned in table 4. 3.3.1.dielectric constant and permit loss the dielectric constant and permit loss change as a frequency behavior from 1 mhz to 3 ghz. the dielectric constant reduces as the frequency rises, as seen in fig. 5. mn0.5ni0.5ndxfe2-xo4 (x = 0.00, 0.05, 0.10, 0.15 and 0.20) almost all spinel ferrite samples showed a steady reduction in the dielectric constant, and all ferrites showed vibration peaks at higher frequencies. the dielectric constant and permit loss showed distribution when the frequency was enhanced. according to maxwell wagner interfacial polarization the grains are much more impressive at high frequencies, whereas at lower frequency the grain boundaries values are more impressive. the process of sintering cause’s polarization between the two surfaces at low frequencies and dipolar are at high frequencies due to the spontaneous scattering of atoms of oxygen at grain boundary and grains (mustaqeem et al., 2020). the polarization was dampened as the frequency was increased. with increasing frequency, the dielectric constant reduces. electrons are the primary charge carriers in ferrites, and electron motion occurs b/w fe2+ –fe3+ atoms located at octahedral sites. this is called hopping method. the transfer of electrons b/w fe2 –fe3 anions at the octahedral site causes a reduction in dielectric constant which rises as frequency rises, and this interchange cannot obey the alteration in an alternating current electric charge. in spinel ferrites, only a few more vibration peaks were found when electron transfer b/w fe2 –fe3 atoms was similar to the given ac frequency. the jumping chance of the both ions was the same if atom has double static conditions c and d that are distinguished by a wall. the frequency which interchanges the position of particle is known as the particle's real frequency. if the internal and external frequencies are equal, then the most electrical energy received the vibrating atom and the loss of influence enhanced. as a consequence, the process of resonance occurred (junaid et al., 2016). as seen in fig.11. figure 11: (a) shows dielectric constant vs frequency and (b) shows the permit loss vs frequency mn0.5ni0.5ndxfe2-xo4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) journal of materials and physical sciences 2(2), 2021 104 3.3.2.tangent loss and ac conductivity the ratio derived from the relationship between current loss and charging is called tangent loss. the change in tangent loss with frequency for mn0.5ni0.5ndxfe2-xo4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) shown in fig.12. the frequency has inverse relation to the tangent loss. it’s clear that when the frequency was increased, the amount of tangent loss decreased (cheng et al., 2018). at lower frequency, electrons' hopping frequency matched the applied field, and loss was relatively high. as the applied field frequency was raised then frequency of hopping b/w fe2–fe3 atom couldn't obey the external field over a particular critical frequency, resulting in a significant reduction in loss. as the doping of rare-earth element nd3+ increased peaks drifted into the lower frequency zone. the resonance frequency was reduced when the doping amount was elevated above a certain amount. the quantity of electric current in a specimen of material is known as ac conductivity. the relationship between ac conductivity and frequency of spinel ferrites is illustrated in fig.13.ac conductivity graph shows that all samples had the same pattern at low frequencies. the high frequency area exhibited dispersion activity. according to koop's principle and the maxwell model the ferrites substance are made up of executing grains distinguished by grain boundaries. however, at higher frequencies, the grains are disturbed, and the hopping process b/w fe2–fe3 atom is enhanced, resulting in increased conductivity (farid, ahmad, ali, mahmood, & ramay, 2018). figure 12: (a) shows tangent loss vs frequency and (b) shows ac conductivity vs frequency of mn0.5ni0.5ndxfe2-xo4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) table 4 dielectric different parameters for mn0.5ni0.5ndxfe2-xo4 3.3.3.real (z') and imaginary (z″) part of impedance the impedance analysis can be used to fully comprehend the electrical nature of spinel ferrites. we use various representations to describe the complex plane, such as electric modulus, permittivity impedance, admittance and dielectric loss etc. impedance performance as the frequency range was 1mhz’ to 3ghz. the impedance of the formulated parameter frequency x= 0.00 x= 0.05 x= 0.10 x= 0.15 x= 0.20 dielectric constant 1 mhz 4.3349 4.9557 6.0769 2.59196 4.9987 1 ghz 2.4859 3.3059 3.8020 2.27187 3.5560 3 ghz 2.3623 3.06931 3.3240 2.12862 3.2209 dielectric loss 1 mhz 0.2371 0.05282 0.9550 0.34757 0.4107 1 ghz -0.0413 0.05562 0.0482 -0.00852 0.0105 3 ghz 0.0612 0.08288 0.0972 0.05972 0.1233 tan loss 1 mhz 0.0547 0.01065 0.1571 0.13409 0.0821 1 ghz -0.016 0.01682 0.0126 -0.00375 0.0029 3 ghz 0.0259 0.02700 0.0292 0.02805 0.0382 ac conductivity 1 mhz 0.0006852 0.0002578 0.0004026 0.0005562 0.0006001 1 ghz 0.0565968 0.0566898 0.0443532 0.0139568 0.0114884 3 ghz 0.2581030 0.1764998 0.2214708 0.3735365 0.3775462 zaheer abbas gilani, muhammad waqas tariq, h. m. noor ul huda khan asghar, naeem khan 105 spinel ferrites raised with increasing rare-earth ions nd3+ doping. z’ and z″ rise with the doping of rare-earth element, but as the frequency of the external field rises, z’ and z″ components of impedance follow the same pattern as impedance, as seen in fig.14. the use of rare-earth ions obstructs electron transfer between the tetrahedral and octahedral sites. the impedance of the processed spinel ferrites reduced as the frequency of the applied field enhanced from 1mhz to 3ghz, as seen in fig.14. the conductivity operating system is exposed to hopping. figure 14: (a) shows the real (z') part of impedance vs. frequency and fig. (b) shows the imaginary (z″) part of impedance vs. frequency 3.3.4.real and imaginary parts of modulus the real (m') and imaginary (m′′) module of spinel ferrite formed according to configuration mn0.5ni0.5ndxfe2-xo4 were computed as the product of the applied frequency. impedance analysis was used to investigate the position of grains and also its boundaries in the range of frequencies of 1mhz to 3ghz. electrical reaction dependent on electric polarization phenomenon on the basis of complex electric modulus parsimony, the bulk grain and grain boundary effects in certain homogeneous materials can be defined. if the grain boundaries area takes up a lot of space, the graph between m' and m" will reveal a lot about the semicircle. this type of approach is verified by a relationship between grain boundaries and peak formation (khera & chand, 2019). the existence of a peak can be seen in the graph of imaginary electric modulus vs frequency. the m' and m″ factor vs the frequency of the applied field was obtained accordingly. the m' and m″ factor have really low values at low frequencies and rise uniformly as the frequency implemented fields rise, whereas they reach highest values at higher frequencies (3ghz) can be seen in fig.15. figure 15: (a) real (m') parts of modulus vs of frequency and fig. (b) was imaginary (m″) parts of modulus vs frequency of mn0.5ni0.5ndxfe2-xo4 journal of materials and physical sciences 2(2), 2021 106 table 5 the different parameters values of dielectric mn0.5ni0.5ndxfe2-xo4 parameters frequency x= 0.0 x = 0.05 x = 0.10 x = 0.15 x = 0.20 zʹ/ohm 1 mhz 6.41e+03 7.15e+03 6.20e+03 1.19e+04 9.01e+03 1 ghz 1.32e+00 1.86e+00 1.19e+00 3.74e-01 3.39e-01 3 ghz 7.42e-01 7.40e-01 8.02e-01 1.23e+00 1.43e+00 zʹʹ/ohm 1 mhz 5.42e+04 9.37e+04 6.97e+04 8.16e+04 6.85e+04 ghz 8.61e+01 1.02e+02 9.24e+01 9.23e+01 9.69e+01 3 ghz 3.02e+01 3.65e+01 3.39e+01 3.23e+01 3.46e+01 mʹ 1 mhz 0.0094757 0.0163736 0.0121886 0.0142733 0.0119817 1 ghz 0.0151428 0.0179712 0.0162394 0.0162265 0.0170421 3 ghz 0.0158596 0.0191519 0.0177978 0.0169551 0.0181704 mʹʹ 1 mhz 0.0011212 0.0012497 0.0010836 0.00208 0.00157513 1 ghz 0.000232 0.0003273 0.0002091 6.568e-05 5.9633e-05 3 ghz 0.0003892 0.000388 0.0004205 0.0006443 0.00074805 4. conclusions neodymium (nd3+) doped mn0.5 ni0.5 ndx fe2-x o4 spinel ferrite nanoparticles were successfully prepared by sol-gel self-ignition method which has been established to be the one of simplest and quickest method for the synthesis of ferrites. various characterizations have been used to examine the effect of nd3+doping such as xrd, ftir and dielectric. xrd verified the crystalline phase and fcc spinel arrangement of the synthesized samples. the crystalline size was determined by sherrer's formula. it was observed in the nano scale ranging between 6 and 10 nanometers. it was observed that the crystalline size differed inhomogeneously with the doping of nd3+. xrd determining different structural parameters of sample, such as lattice strain, lattice constant, x-ray density, unit cell volume, bulk density, micro-strain, stacking fault and dislocation density. the lattice parameter changed when the nd3+ doping concentration was enhanced because smaller radius of fe3+ ions is replaced by large ionic radius of nd ions. ftir verified the cations distribution and investigated the tetrahedral and octahedral frequency bands. dielectric properties of fabricated spinel ferrites were identified at frequencies ranging from 1 mhz to 3 ghz. dielectric was used to determine the effect of nd3+ doping on various parameters such as the a.c conductivity, real and imaginary parts of the modulus, impedance, dielectric constant, electric modulus, and tangent loss was analyzed. these properties play a significant role and essential due to their uses in high frequency products. dielectric investigations showed decline in dielectric constant. impedance analysis exhibited a reducing value with frequency, due to the increase in material conductivity. real and imaginary modulus study showed the influence of grain boundaries at low frequencies. these dielectric properties suggested that these materials could be used in high-frequency applications and semiconductor devices. acknowledgement we are grateful to oric of balochistan university of information technology, engineering and management sciences (buitems), quetta pakistan. references adam, j. d., davis, l. e., dionne, g. f., schloemann, e. f., & stitzer, s. n. 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(2019). lattice strain advances thermoelectrics. joule, 3(5), 1276-1288. https://doi.org/10.52131/jmps.2020.0102.0009 87 journal of materials and physical sciences volume 1, number 2, 2020, pages 87 97 journal homepage: https://journals.internationalrasd.org/index.php/jmps magnesium ferrite/polyvinyl alcohol (pva) nanocomposites: fabrication and characterization gulfam nasar1*, muhammad ishfaq2, fawad ahmad3, shahbaz nazir4, faseeh ur raheem5 1 department of chemistry, balochistan university of information technology, engineering and management sciences, quetta 87300, pakistan 2 punjab higher education department, govt. graduate college chishtian, bahawalnagar, pakistan 3 department of chemistry, university of wah, quaid avenue, wah cantt 47040 pakistan 4 punjab higher education department, govt. graduate college ravi road shahdara, lahore, pakistan 5 institute of physics, the islamia university of bahawalpur, bahawalpur 63100, pakistan article info abstract article history: received: october 08, 2020 revised: november 17, 2020 accepted: december 19, 2020 available online: december 31, 2020 terbium doped magnesium spinel ferrites (mg1-xtbxfe2o4) with composition x=0.12, 0.14, 0.16, 0.18 were synthesized via micro-emulsion method followed by synthesis of pva/mg1xtbxfe2o4 composites using in-situ polymerization technique. the structural properties were evaluated using x-ray diffraction (xrd) and fourier transform infra-red spectroscopy (ftir). xrd analysis confirmed the construction of spinel lattice of terbium ferrite whereas ftir revealed the interactions between ferrite nanoparticles and polyvinyl alcohol matrix. the xrd and ftir results quite matched with the reported literature. the dielectric and resistivity analyses were performed by determining dielectric parameters and currentvoltage measurements. the values of dielectric constant, dielectric loss and tan δ were found to be inversely proportional to the frequency under the ambient electric field at room temperature but became constant at higher frequency values. the lower values of dielectric constant of terbium incorporated magnesium ferrite polymer composites (mgfe2o4/pva) are attributed to hindrance in ‘electron exchange mechanism’ created by lockup between iron and terbium ions. the resistivity values of all the composites were found from 2.5x109 ωcm to 18.8x109 ωcm which showed a nonlinear behavior. keywords: spinel ferrites pva composites xrd ftir dielectric properties current-voltage measurements © 2020 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: gulfamnasar@gmail.com 1. introduction nanotechnology has exposed itself as the technology of miniaturization with an aim of making inexpensive, lighter and smarter goods having smaller sizes. nano ferrite particles (having size less than 100 nm) have become much important during the last few decades and are considered as an effective link that bridges bulk substances and atomic or molecular materials(abdelwahab & shukry, 2015). soft ferrites possess cubic spinel structure that is derived from mgal2o4,(reddy & yun, 2016)whose structure was interpreted by bragg. the general formula of magnetic spinels is mfe2o4 where m is a divalent transition element such as mn, fe, co, ni, cu and cd (al-ghamdi, al-hazmi, memesh, shokr, & bronstein, 2017). all the ferrites contain iron oxide as the main constituent in their structures. the metal ions like ni2+, co2+ and mn2+ may also be used to offer the unpaired electron spins. the magnetic moment may also be disturbed by the incorporation of some non-paramagnetic ions such as mg2+ or zn2+ or monovalent li, causing the variation in concentration of fe3+ ions on the crystal lattice points. the spinel ferrites have received a lot of reputation. they have shown advantages of high saturation magnetization, high https://journals.internationalrasd.org/index.php/jmps mailto:gulfamnasar@gmail.com gulfam nasar, muhammad ishfaq, fawad ahmad, shahbaz nazir, faseeh ur raheem 88 electrical resistivity, high magnetic loss and low eddy current losses (wang, huang, wang, he, & chen, 2012). generally the ferrite materials are cheap, stable and possess numerous applications related to technological and industrial fields(davachi et al., 2016). they are used as microwave absorbers such as gas sensors(balgis, iskandar, ogi, purwanto, & okuyama, 2011), isolators, gyrators, phase shifters, radio wave circuits, electronic equipment(nasar et al., 2016), electrode materials, microwave dark rooms and protection, magneto-optical storage media manufacturing phenomena, optics and conducting adhesive materials, high density digital recording discs, spintronics(mohamed, rashad, haraz, & sigmund, 2010), noise filters(chitra, muthusamy, dineshkumar, jayaprakash, & chandrasekar, 2015), hyperthermia(jaberolansar, kameli, ahmadvand, & salamati, 2016) high performance engineering materials and compact power supplies (xiao, liu, & fu, 2006). material scientists have been making efforts to improve the properties of the nanofibers. it has been reported that sintering temperature and variation of different metal ions (dopants) especially of lanthanide series are observed to improve the electrical and magnetic properties of ferrite material effectively. the special emphasis on rare earth elements is due to their 4f unpaired electrons screened by 5s2 5p6 electrons and strong spin –orbit coupling of the angular momentum which are not affected by the potential field of nearby ions and which can originate magnetic anisotropy owing to their orbital shape(sun et al., 2015). ferrites can be synthesized either by dry or wet method. the wet chemical routes include a vairiety of the processes comprising micro-emulsion, sol-gel, mechanochemical, hydrothermal, sol-spray drying, sonochemical, solvothermal, coprecipitation processes etc. (naz, durrani, mehmood, & nadeem, 2014). rapidly developing field of polymer based nanocomposites has created a lot of inspiration for researchers during the recent years. nanocomposites are known to possess multi-range systems as 1d, 2d, 3d and amorphous materials composed of diverse constituents at the nm size(khairy & gouda, 2015). they have various useful utilizations in electro-optical integrated instruments, energy storage devices (gairola et al., 2010). the efficiency of nanoferrite particles can be improved by incorporating them in polymer matrix owing to high surface area to volume ratio. polymer nanocomposites are used in packaging materials, refractory materials(chitra, muthusamy, & jayaprakash, 2015), high frequency multilayer chip inductors, transducers(chen et al., 2016), optical integrated circuits, medical instruments, drug delivery from compartmented nanotubes, immobilization of biological objects like proteins, tissue engineering, fire retardants, adhesives, consumer goods etc.(song, shen, liu, & xiang, 2011). polymers used as matrix in magnetic nanocompoistes are commonly categorized in a number of classes such as neutral, charged, hydrophilic, homopolymers, co-polymers etc.(fang & zhang, 2009). poly vinyl alcohol (pva) is a synthetic polymer with poor electrical conductivity. it is commonly used owing to its diverse properties; such as solubility in water, excellent durability, moisture barrier film behavior,(hmar, majumder, & mondal, 2016) semi-crystallinity, non-toxicity, better flexibility, highly transparent feature and emulsifying, biocompatibility, adhesion, biodegradability, very fine film making abilities etc. it is easily available and easy to handle(kashyap, pratihar, & behera, 2016). a number of techniques have been reported fo synthesis of polymer nanocompoistes such as in-situ polymerization, electrochemical, micro-emulsion, electro spinning etc.(bose et al., 2010). rashidi, s. and a. ataie used a two-step mechanical milling technique to manufacture the advanced functional magnetic nanocomposites having polyvinyl alcohol and cobalt ferrite (pva/cofe2o4) as main constituents. they reported the effects of milling time and polymer fraction. they prepared the spherical single-phase cobalt ferrite of about 20 ± 4 nm and embedded them in pva by rigorous milling. the synthesized nanomaterial showed decreasing trend in magnetic properties like saturation magnetization, coercivity and anisotropy constant values(s rashidi & a ataie, 2016). we report an innovative, cheaper, facile and economical method of synthesizing pva/mg1-xtbxfe2o4 nanocomposites using in-situ polymerization technique via ultrasonication. the effect of tb substitution with mg has been studied in terms of morphology, electrical and dc conductivity of pva/mg1-xtbxfe2o4 nanocomposites. journal of materials and physical sciences 1(2), 2020 89 2. experimental procedure 2.1. chemicals used the following chemicals were used for the synthesis of pva/mg1-xtbxfe2o4 nanocomposite materials. magnesium chloride, mgcl2.4h2o (sigma-aldrich, 98%), terbium chloride, tbcl3.6h2o (sigma-aldrich, 99.9%), iron chloride, fecl3.6h2o (merck, 99%), aqueous nh3 (bdh, 35%), polyvinyl alcohol (pva), arcos, england (mol. wt= 70,000 g mol1), ctab, cetyltrimethyl ammonium bromide, (c16h33) n (ch3)3br, (amresco, 98%), sodium carbonate, naco3, (riedel-dehaen) and de-ionized water. all the chemicals were used as received without further purification. 2.2. synthesis of mg1-xtbxfe2o4 nanoparticles terbium doped mg1-xtbxfe2o4 nanoferrites with composition x=0.12, 0.14, 0.16, 0.18 were prepared via wet chemical route i.e. micro-emulsion method. the stoichiometric amounts of reagents were dissolved in de-ionized water. the solutions were stirred using magnetic stirrer at 50-60co. and “ctab” was added drop-wise to the stirring solutions. the ph 10-11 was attained by adding 2m aqueous solution of nh3 while the stirring was continued for further 5-6 hours. the precipitates were washed with de-ionized water several times to obtain ph 7, followed by drying in oven at 100 co. the prepared samples were annealed at 700 co for 7 hours in muffle furnace at heating rate of 5 co /min. the synthesized mg1-xtbxfe2o4 nanoferrites were ground finely using ultraclean pestle and mortar (khan, islam, ishaque, & rahman, 2012). 2.3. synthesis of pva/mg1-xtbxfe2o4 nanocomposites the pva/mg1-xtbxfe2o4 nanocomposites were synthesized via ultra-sonication. five compositions of nanocomposites were prepared with 1.5 g of pva in each composition. likewise a blank pva film was prepared for comparison. mg ferrite was added in each composition as x (x = 0.12, 0.14, 0.16, 0.18). the solution of polymer was prepared by stirring and at 70-80 co using de-ionized water as solvent. finely ground mg1-xtbxfe2o4 nanoparticles were suspended via sonication in de-ionized water. both the solutions were mixed and sonicated at 60-70 co for two hours. the resulting solution was poured in petri dish and dried at room temperature to get thin film of pva/mg1-xtbxfe2o4 nanocomposites. 3. results and discussion 3.1. x-ray diffraction (xrd) xrd diffraction of pure pva and the pva/mg1-xtbxfe2o4 nanocomposites films was carried out by bruker axs gmbh, ostliche rheinbruckenstr, 76187 karlsruhe germany/alemania/allemagne using cu kα radiation of wavelength λ=1.54060å filtered with “ni”. xrd profile of pure pva and pva/mg1-xtbxfe2o4 nanocomposites (x=0.12 to 0.18) is shown in fig.1. the results show the main peak at 2θ=19.8o which corresponds to (101) crystal plane of pure pva indicating its semi-crystalline nature as reported by mohanapriya, m.k., et al(mohanapriya, deshmukh, ahamed, chidambaram, & khadheer pasha, 2016). some other diffraction peaks indexed as (220), (311), (400), (422), (511) and (440) at 2θo values, 30.1, 35.39, 42.97, 53.50, 57.09, 62.62 respectively. the most dominant peak appeared at 35.39o corresponding to crystal plane (311) which is the confirmation of single phase fcc spinel structure of mgfe2o4.these observed xrd profiles of the composites have a perfect matching with those of standard diffraction profiles of jcpds card # 36-0398. all the above mentioned diffraction profiles have already been reported and revealed the fcc single spinel structure of the resulting pva/mg1-xtbxfe2o4 nanocomposites. the prominent peak relating to (311) plane is present in all the synthesized nanocomposites. the intensities of two more planes i.e. (220) and (400) are also much sensitive to cations on tetrahedral (a sites) and octahedral (b sites) sites respectively. observations through experiments have demonstrated that mg2+ has a strong preference to occupy b-sites and partially occupy a-sites. gulfam nasar, muhammad ishfaq, fawad ahmad, shahbaz nazir, faseeh ur raheem 90 the ionic radii of mg2+ and tb3+ are 0.66å and 0.93 å respectively. the observed intensities of the above mentioned peaks decline remarkably by the substitution of tb3+ by mg2+ ions. the intensity of peak corresponding to plane (400) is relatively more decreased because of this substitution which largely depends upon the bigger size of tb3+ ions. the various lattice parameters are calculated using the following relationships: figure 1: xrd pattern of uncoated pva and pva/mg1-xtbx fe2o4 nanocomposites crystalline size (d) = 0.9λ βcosθ (debye-scherer’s formula) (1) where β is the average full width at half maxima (fwhm), θ is the bragg’s angle and λ is the x-ray wavelength. x-ray density (ρ x-ray) = 8m nav (2) where m is the mass of the composite, na is the avogadro’s number and v is the volume of the composite film. bulk density (ρ bulk) = m v (3) where ‘m’ is mass and ‘v’ is the volume of thin film. porosity (p) = 1 ρbulk ρx−ray (4) table 1: different values of lattice parameters of pva/mg1-xtbxfe2o4 (x=0.12, 0.14, 0.16, 0.18) sample composition lattice constant(a) å cell volume (å)3 x-ray density (gcm-3) bulk density (gcm-3) porosity (p) crystallite size (nm) x=0.12 8.39 590.59 4.86 2.58 47 30.96 x=0.14 8.38 588.48 4.94 2.89 41 23.76 x=0.16 8.36 584.28 5.04 2.49 50 31.06 x=0.18 8.35 582.18 5.12 2.61 49 25.36 journal of materials and physical sciences 1(2), 2020 91 3.2. fourier-transform infra-red spectroscopy (ftir) the fourier transform infrared spectroscopy of pure pva and nanocomposite films was carried out using midac m 2000 with wavenumber range 600-4000 cm-1 in transmittance mode. the obtained spectrum has the set of absorption bands whose intensity and frequency offer facts about structure and bonding within the molecule (kubicki et al., 2012). ftir spectra of pure pva and nanocomposites are shown in fig 2. in case of pure pva, the main absorption peaks are found at 3295 cm-1, due to o-h stretching (responsible for h-bonding), 2927cm-1,is due to c-h stretching,1729 cm-1 and1567 cm-1 correspond to c=o stretching and c=o asymmetric stretching and near 1419 cm-1 ,due to c-h bending vibrations. the absorption peaks located near 1148 cm-1 and 1090 cm-1 reveal the stretching mode of fe-o-fe groups (s. rashidi & a. ataie, 2016). the presence of all these peaks confirms the existence and incorporation of pure pva matrix in all the resulting pva/mg1-xtbxfe2o4 nanocomposites. figure 2: ftir spectra of pure pva and pva/mg1-xtbx fe2o4 nanocomposites 3.3. dielectric measurements 4287 a rf lcr meter was used to determine the dielectric measurements in the frequency range of 0.0-3ghz at room temperature. these measurements are much important for engineers and material scientists to design electronic devices. the thin films of pure pva matrix and the fabricated pva/mg1-xtbxfe2o4 nanocomposites (x=0.12, 0.14, 0.16, 0.18) were analyzed. dielectric constant , which is a measure of extent of polarization of a material, depends upon the structure of the materials, composition and the method of preparation involved (lodhi et al., 2014). the dielectric parameters like dielectric constant (ε'), dielectric loss and dielectric tangent loss (tanδ) were measured. it is notable that all the dielectric parameters are function of the applied alternating current field in the above mentioned frequency range. the dielectric constant was calculated with the help of equation 5 (khan et al., 2012). ε' = 𝑐𝑑 ε0 a (5) gulfam nasar, muhammad ishfaq, fawad ahmad, shahbaz nazir, faseeh ur raheem 92 where d is the thickness of the material, c is the capacitance of the material, is the permittivity of free space and a is the cross-sectional area of the flat surface of the material in m2. the variation of dielectric constant (ε') as function of frequency has been shown in figure 3. figure 3: the variation of dielectric constant with frequency of pure pva and pva/mg1-xtbx fe2o4 nanocomposites. the values of dielectric constant show a decreasing trend with the successive exchange of tb3+ ions. in the spinel structure of magnesium ferrite (mgfe2o4), there are two sites namely a-sites (tetrahedral) and b-sites (octahedral). it is well-known that most of the mg ions occupy on b-sites whereas fe ions occupy on both a and b-sites (hemeda, said, & barakat, 2001). dielectric constant values gradually decrease with substitution of terbium ions with magnesium ions. this is attributed to the increase of tb ions substitution on b-sites replaces some mg ions (number of mg ions on b-sites decreased) which leads to the reduction in population of fe2+ ions (mg2+ + fe3+↔ mg3+ + fe2+) on b-sites. as a result, the electron exchange interaction happening at b-sites between the fe3+ ions and fe2+ ions hindered due to the existence of tb ions on b-sites, so the hopping length of conduction electrons rises. thus, description justifies the decrease in the dielectric constant values with the growing concentration of tb ions. initially, the dielectric constants for pure pva and all the fabricated samples decrease more rapidly with an increase in frequency (low region) but in the high frequency region, the value drops down to minimum and becomes almost constant. at lower frequencies, the higher values of dielectric constant are attributed to some polarizations like space charge, dipolar, ionic and electronic types (choudhury, rodríguez, bhattacharya, katiyar, & rinaldi, 2007). this behavior can be explained on the basis of the maxwell wagner model which is in agreement with koops phenomenological theory (costa, tortella, morelli, & kiminami, 2003). an additional interfacial space charge polarization plays a prominent role in these types of heterogeneous composites and that increases the dielectric constant. the interfacial polarization gives response very slowly to the external field; therefore, it governs largely in the low frequency region and has no significant influence in the high frequency region. dielectric constant values become constant at higher frequency values attributed to   journal of materials and physical sciences 1(2), 2020 93 the fact that space charge carriers(dipoles) of the composite material do not find much time to re-orient themselves (lagging off polarization) in the direction of the applied electric field (ali et al., 2014). the dielectric loss measures the loss of electrical energy from the applied electric field into the samples at different frequencies. the dielectric tangent loss (tanδ) was calculated using the relation 6 (mohamed et al., 2010). tanδ = ε′′ ε′ (6) figure 4: the variation of dielectric tangent loss with frequency of pure pva and pva/mg1-xtbx fe2o4 nanocomposites where tanδ is the loss angle, is the imaginary part of the dielectric constant and is the total amount of the absorbed energy by the material used from the alternating field is the real part of the dielectric constant. the graph of dielectric loss tangent versus frequency is depicted in figure 4. the variation of dielectric loss with frequency in the applied electric field is quite similar to the real part of the dielectric constant (ε') and depends upon conduction mechanism, composition of material, annealing temperature, synthesis technique, crystalline size etc. electron hopping and defect dipoles are major contributors in this regards. electron hopping is responsible only in low frequency region and it becomes ineffective at higher frequency values, hence dielectric loss decreases. the dielectric loss also shows the peaking behavior i.e. resonance peaks have been observed at higher frequency values as cleared from the fig. 4. at high frequency, it is the jumping frequency of fe2+ and fe3+ which becomes equal to the frequency of applied electric field. this peaking behavior is because of debye-type relaxation. the loss factors of these samples have been observed to decrease with the increase in frequency as shown in figure 5. it has been demonstrated that ionic radius of doping species (tb3+) is directly proportional to the polarization and the frequency of the applied electric field vary to the inverse of polarization. as the concentration of tb3+ increases, the grain size also increases but grain boundaries per unit volume decrease which ultimately reduces the dielectric loss. all the tb3+ substituted samples exhibit low values of loss factor as compared to the unsubstituted sample. in the high frequency region, the loss factor indicates very small values. (khan et al., 2012).     gulfam nasar, muhammad ishfaq, fawad ahmad, shahbaz nazir, faseeh ur raheem 94 figure 5: the variation of dielectric loss factor with frequency of pure pva and pva/mg1-xtbx fe2o4 nanocomposites 3.4. current-voltage measurements (i-v) the current–voltage specific (i–v) curve is a typical graphical relationship between the electric current passing through a substance and its corresponding voltage across that substance. the graph obtained through this procedure is helpful for electronic engineers to decide the fundamental behavior of the substance in the electric powered circuit (van der bijl, 1919). current-voltage study of the synthesized pva/mg1-xtbxfe2o4 nanocomposites (x=0.12, 0.14, 0.16, 0.18) was done using 6487 pico ammeter/voltage source (kiethely) at standard conditions. the voltage of the used apparatus was adjusted at -5 to 5 volts. the resulting i-v curves of pure pva and pva/mg1-xtbxfe2o4 nanocomposites (x=0.12, 0.14, 0.16, 0.18) as shown in figure 6. to calculate the values of resistivity, the following formula was used. resistivity = ra l (7) where l, a and r are taken as thickness, area and resistance of polymer composite films respectively as reported by shahzad, m.a., et al(shahzad, warsi, khan, iqbal, & asghar, 2015). the resistivity values obtained of all the composites are shown in the table 4.2 having the range of 2.5x109 ωcm to 18.8x109 ωcm which showed a nonlinear behavior. it was due to the substitution of tb3+ in the base materials as reported by rasheed, a., et al(rasheed et al., 2016). journal of materials and physical sciences 1(2), 2020 95 figure 6: current voltage (i-v) characteristics of pure pva and pva/mg1-xtbx fe2o4 nanocomposites table 2 resistivity values of pure pva and pva/mg1-xtbxfe2o4 nanocomposites (x=0.12, 0.14, 0.16, 0.18) sr. no composition resistivity (ώcm) 1 pva 2.5 x 109 2 mg0.88tb0.12fe2o4 2.08 x 10 9 3 mg0.86tb0.14fe2o4 8.5 x 10 9 4 mg0.84tb0.16fe2o4 18.8 x 10 9 5 mg0.82tb0.18fe2o4 4.47 x 10 9 4. conclusion nanocrystalline magnesium ferrites with terbium substitution (mg1-xtbxfe2o4) having composition, x=0.12, 0.14, 0.16, 0.18 were successfully prepared followed by synthesis of pva/mg1-xtbxfe2o4 nanocomposites employing a cheaper wet chemical method and solution casting technique respectively. the xrd and ftir studies demonstrated the fcc single phase spinel structure. the interactions between nanoferrite particles and pva matrix is also confirmed. the lattice constants and subsequently cell volume decreased with increasing tb3+ content. the dielectric and i-v values were measured to elucidate the practical applications. the dielectric constants and dielectric loss (tanδ) for all the synthesized materials had an inverse relationship with the frequency in the applied electrical field. the dielectric parameters also showed an inverse behavior with resistivity. references abdelwahab, n. a., & shukry, n. 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karachi 24700, pakistan article info abstract article history: received: may 01, 2020 revised: june 12, 2020 accepted: june 28, 2020 available online: june 30, 2020 in the modern world researchers caught the attraction towards spinal ferrites. the current work is based on spinel ferrites having formula ni0.5co0.5cexfe2-xo4 where (x = 0.0, 0.05, 0.1, 0.15, 0.2) prepared by co-precipitation method. the confirmation of spinal ferrite structure was done through xrd analysis. the crystallite size was found to be in the range of 8 to 11 nm. lattice perimeter is observe to obey the increasing trend due to replacement of larger ionic radii of cerium with smaller ionic radii of iron. koop's phenomenological theory, maxwell–wagner interfacial polarization and vegard’s law is used to explain the behavior of lattice constant. the electrical properties of prepared ferrites were revealed by impedance analyzer. various parameters like real and imaginary parts of dialectic constant, impedance and modulus was determined. in the frequency range of 1 to 3 ghz the detailed electrical inspection was done. during the electrode polarization the effect of grains on the increasing substitution of cerium was analyzed through real and imaginary parts of electrical modulus m' and m". in the frequency range of 3 ghz the value of m' is 2.1934 × 10-1 to 2.6581 × 10-1 and the value of m" is from 4.67 × 10-3 to 3.538 × 10-3. ac conductivity spectra shows a non-debye relaxation behavior and it dependents of conductivity on frequency. the observed dielectric constant, dialectic loss and tangent loss are found to be decreasing with the increase in frequency. the investigation shows that real and imaginary impedance z' and z" was found to be decreasing on lower frequencies and on higher frequencies all the curves merge with each other. the value of z' and z" at 3ghz frequency is in the range of 8.02 × 10-3 to 0.6073 and 3.7641 to 4.5617 respectively. increase in frequency increases the ac conductivity. the applications of prepared nanoparticles are suggested in high frequency devices because of the splendid dielectric properties of these particles. keywords: spinel ferrite nicofe2o4 ce3+ doping co-precipitation dielectric properties xrd ftir © 2020 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: noorulhudakhan@gmail.com 1. introduction spinel ferrites occupy polycrystalline nature. the immense significance of spinel ferrites is due to its extrinsic applications in various electronic fields. these ferrites are preferred on other materials because of its certain features like high electrical resistivity, high permeability and saturation magnetization in the radio frequency (aslam et al., 2019). the ab2o4 crystal structure of spinel ferrites provides them the best magnetic properties (peelamedu, grimes, agrawal, roy, & yadoji, 2003). the huge dialectic and electrical https://journals.internationalrasd.org/index.php/jmps mailto:noorulhudakhan@gmail.com saira yasmeen, h. m. noor ul huda khan asghar, zaheer abbas gilani, muhammad khalid 27 characteristics of spinal ferrites depends on its chemical composition and method of its preparation (farid et al., 2017). the significance of multi-ferroic materials is due to their ferromagnetic, ferroelectric and ferro elastic characteristics. when the stress, magnetic field and electric field is applied on ferrites, the deformation polarization and change in spontaneous magnetization occurs respectively. the applications of these materials are in sensing, storage and spintronic devices is due to the phenomena of mutual coupling (sheikh et al., 2019). annealing and composition are used to control the dialectic parameters like dialectic constant, tangent loss, ac conductivity and impedance (al-hilli, li, & kassim, 2012; nambikkattu, kaleekkal, & jacob, 2020). the attention towards cobalt ferrites is given because of their tremendous uses in high electromagnetic, industrial and biomedical applications. these ferrites occupy high chemical stability (bilecka, kubli, amstad, & niederberger, 2011; franco jr & e silva, 2010). the reduction in saturation magnetization occurs due to the week interaction of sub lattices and decrease in magnetic moments, this is because of the ionic radii of ce3+(1.03a°) ions are larger than the fe3+(0.64a°) ions (elayakumar et al., 2019). structural parameters like lattice constants and crystallite size reduces. this reduction occurs because of ce3+ doping which has the capability to impede the grain growth (sobhani-nasab, ziarati, rahimi-nasrabadi, ganjali, & badiei, 2017). when the rare earth ions are doped to spinel structure, the interaction between ce3+ and fe3+ occurs with 3d-4f electron coupling. this coupling reduces the magnetic exchange interaction between a and b site which ultimately causes the small variation in magnetization due to antiferromagnetism. interaction between the couplings of fe3+-o2--ce3+ is very weak. the decrease in the saturation magnetization increases the cerium constant which makes the sample suitable for technical applications (sagayaraj, aravazhi, & chandrasekaran, 2019). the details study of dielectric and impedance properties of cerium ferrites is done which were prepared by coprecipitation method. 2. materials and method 2.1. fabrication of ni0.5co0.5cexfe2-xo4 (x = 0.0, 0.05, 0.1, 0.15, 0.2) nano crystalline spinal ferrites with formula ni0.5co0.5cexfe2-xo4 where (x = 0.0, 0.05, 0.1, 0.15, 0.2) were prepared through coprecipitation method. the chemicals used for this composition are nickle nitrate-6-hydrat (ni (no3)2.6h2o) m.w=290.81, made by riedel-de hean-a6 seelze-hannover ,cobalt (ii) nitrate hexa-hydrate (co (no3)2. 6h2o) m.w= 291.03 made by sigma-aldrich, cerium (iii) nitrate hexa-hydrate (cen3o9.6h2o) m.w= 434.2, made by aldrich, ferric (iii) nitrate nano-hydrate (fe (no3)3.9h2o) m.w= 404, made by gpr. table 1 represents the various concentrations of materials used. table 1 concentration of materials used sample no ni (0.4m) co (0.4m) ce (0.8m) fe (0.8m) 1 26ml 26ml 0.0ml 52ml 2 26ml 26ml 1.25ml 50.75 ml 3 26ml 26ml 2.5ml 49.5ml 4 26ml 26ml 3.75ml 48.25ml 5 26ml 26ml 5ml 47ml volume required 130ml 130ml 12.5ml 247.5ml total volume 130ml 130ml 14ml 260ml the steps followed for this experimental work are preparation of solution, stirring of solution, drying of sample, sample's grinding, annealing and pelleting. for the preparation of sample distilled water was used. magnetic hot plate was used for stirring and mixing of all the solution of required quantities at 50° c. the ph values of all the solutions were maintain through ammonia solution. in further 5 hours the stirring of solution was done. the ph of the samples were reduce to 7 by the several times washing of precipitates. sample’s water was evaporated at 80°c in electrical oven. muffle furnace was used to anneal the sample at 800°c for 6 hours. all the samples were grinded into powder form for the characterization purpose (gilani et al., 2015). xrd advance diffractometer were used to examine the xrd patterns of all the compositions of ni0.5co0.5cexfe2-xo4. fourier transform infrared spectroscopy was done to investigate the chemical changes. in the frequency range journal of materials and physical sciences 1(1), 2020 28 of 1-3 ghz, inspection of dielectric impedance and modulus spectroscopy was carried out at room temperature. 3. results and discussion 3.1. x-ray diffraction analysis the structure of fabricated ferrites ni0.5co0.5cexfe2-xo4 where (x = 0.0, 0.05, 0.1, 0.15, 0.2) and their pattern were analyzed through xrd. the features of observed sample are given in figure 1. 10 20 30 40 50 60 70 80 in te n si ty / a r b . u n it s angle 2 theta/(degree) x=0.0 x=0.05 x=0.10 x=0.15 x=0.2 220 311 400 511 440 531 * figure 1: xrd analysis of ni0.5co0.5cexfe2-xo4 (x=0.0, 0.05, 0.1, 0.15, 0.2) the annealing temperature of sample were 800°c. the fcc cubic spinel structure with single phase was obtain and it is confirmed by all the peaks in xrd patterns. the magnitude of crystalline phases is observed to alter with ce3+ doping. the most strong peak is achieved at 2 = 35.56 for the concentration x=0.2, which is typically considered to be the ideal peak for cubic crystal formations. other peak analyses were (220), (311), (400), (511), (440), and (440), (531). the presence of these peaks indicates that the prepared structure is an fcc spinel structure. jcpds card number 22-1086 is also used to confirm the structure. the observations shows that all of the peaks were broad, indicating that the ferrite has been processed nano crystalline structure. there are also some impurity peaks, one of which is 2 = 76.7, with a hkl value of (633). the insoluble cerium phase at the octahedral location may cause these secondary peaks to arise (gilani et al., 2015). the appearance of this peak is may be due to the excessive ce3+ ions at octahedral site because as compared to host fe3+, they have larger ionic radii. to find the actual crystallized size debye scherer’s formula was used (al-hilli et al., 2012). d = 0.9 λ / β cosθ (1) the crystalline size is indicated by “d”, the wave length of x-rays is lambda (1.54a°). the diffraction angle is “θ” and ‘β” is for full width at half maximum. the crystalline size was observed to be 8-11 nanometer. crystalline sizes and lattice constants of prepared samples are given in figure 2. saira yasmeen, h. m. noor ul huda khan asghar, zaheer abbas gilani, muhammad khalid 29 0.00 0.05 0.10 0.15 0.20 8.0 8.5 9.0 9.5 10.0 10.5 11.0 concentration (x) c r y st a ll in e s iz e ( n m ) 8.10 8.15 8.20 8.25 8.30 8.35 8.40 l a tt ic e c o n st a n t (a o ) figure 2: crystalline size and lattice constant as a function of concentration of ni0.5co0.5cexfe2-xo4 (x=0.0, 0.05, 0.1, 0.15, 0.2) it is investigated that crystalline sizes first increases then decreases with doping concentration. this inhomogeneous behavior is due to interchanging of larger ionic radii with smaller ionic radii of fe3+. it is analyzed that the lattice constant increases with the substitution of cerium which is calculated by nelson riley function and it is shown in figure 2. due to their higher ionic radii, rare earth cations have a natural tendency to occupy the octahedral site (junaid et al., 2016). the behavior of lattice parameter can be explain by vegard’s law. many parameters, such as ionic radii, crystallite shape, surface structure, and long-range interactions, all play a role in lattice constant. coulomb forces have an effect on the lattice constant, which could explain the previously reported abnormal behavior (khan et al., 2020). the perimeter like cell volume, x-ray density, bulk density, lattice constant and crystalline sizes are given in the table 2. the table 2 shows the different parameters like crystalline size, lattice constant, unit cell volume, x ray density and bulk density. table 2 various parameters of x-ray analysis parameter x=0 x=0.05 x=0.1 x=0.15 x=0.2 crystalline size (nm) 8.299 11.011 9.463 9.648 9.968 lattice constant α (å) 8.141 8.355 8.309 8.302 8.357 cell volume (α3) 539.6 583.3 573.7 572.2 583.6 x-ray density (g/cm3) 5.773 5.435 5.624 5.737 5.720 bulk density(g/cm3) 2.827 3.293 3.589 3.280 3.662 lattice strain x 10-3 1.435 1.06 1.25 1.22 1.16 micro strain x 10-3 (lines-2/m-4) 4.17 3.14 3.66 3.59 3.47 dislocation density x 1015(lines/m2) 14.51 8.24 11.16 10.74 10.06 stacking fault 0.442 0.446 0.443 0.444 0.447 the observed most intense peaks are identified at (311). the increase in lattice constant is due to the larger ionic radii of cerium as compared to host cations of fe3+ (junaid et al., 2016). the relation used to calculate the x-ray density is x-ray density = 8m / nα3 (2) molecular weight of sample is identified by "m", avogadro’s number is "n" and volume of cubic unit cell is represented by alpha3. the relation for bulk density is bulk density = m/v (3) pellet thickness is represented by "h" where “m” and “r” are mass and radius of pellet respectively. journal of materials and physical sciences 1(1), 2020 30 3.2. fourier transform infrared analysis the spinel phase of all the compositions are confirmed through ftir. table 3 shows the variation with ce3+ concentration in vibrational bands and force factors (aslam et al., 2019). the values of the different parameters of ftir analysis are shown in the table 3. table 3 different parameters of ftir studies parameters x=0 x=0.05 x=0.1 x=0.15 x=0.2 molecular weight (g/mol) 235 239 243 247 251 ʋ1 (cm-1) 532 537 532 532 530 ʋ2 (cm-1) 417 418 410 418 418 ko (dyne/cm 2) x 105 1.44155 1.45154 1.39938 1.45742 1.46022 kt (dyne/cm 2) x 105 2.60087 2.63720 2.56791 2.62322 2.61839 ro 0.7152 0.7689 0.7574 0.7555 0.7693 rt 0.4426 0.4891 0.479 0.4775 0.4894 this spectroscopy also gives information about the cations distribution and chemical changes. two main frequency bands are analyzed, one is high frequency band and other is low frequency bands. the values of these bands are around 530 cm-1 and 400 cm-1 respectively (assar, abosheiasha, & el nimr, 2014; junaid et al., 2016). the distinguishing features of spinel ferrites were thoroughly examined by these frequency bands due to the octahedral stretching bands. the vibrations in high frequency band are measured between 530 and 538 cm-1, where the changes in low frequency band are measured between 410 and 418 cm-1. the force constants (k°) at octahedral side and (kt) at tetrahedral sites are obtained by the following: ko =0.942128 m (ʋ2)2 / m+32 (4) kt = (2)1/2 × ko ʋ1/ʋ2 (5) the tetrahedral and octahedral radii can be calculated by: rtetra = a (3)1/2 (u-0.25) – ro (6) rocta = a (5/8-u) ro (7) where the specimen have molecular weight "m". for the fcc structure, the oxygen parameter is represented by u, and its value is 0.375. the lattice parameter is indicated by the letter "a" (cao et al., 2018). it is observed that when cerium is doped, the strength of interatomic bonding increases with the increase in force factors. figure 3 shows the ftir spectra of ni0.5co0.5cexfe2-xo4 (x=0.0, 0.05, 0.1, 0.15, 0.2). 400 500 600 700 800 900 1000 t ra n s m it ta n c e / % wave number / cm -1 x=0.0 x=0.1 x=0.15 x=0.05 x=0.2 417 532 418 537 410 532 418 532 418 530 figure 3: ftir analysis of ni0.5co0.5cexfe2-xo4 (x= 0.0, 0.05, 0.1, 0.15, 0.2) saira yasmeen, h. m. noor ul huda khan asghar, zaheer abbas gilani, muhammad khalid 31 3.3. dielectric properties ferrite’s dielectric characteristics are critical, as we know, because of this ferrites are used in a variety of high-frequency applications. the technique of preparation, composition, and annealing time and temperature all play a role in these applications. dielectric parameters such as dielectric loss, dielectric constant, tangent loss, real and imaginary parts of impedance, electric modulus, and ac conductivity of ni0.5co0.5cexfe2-xo4 (x= 0.0, 0.05, 0.1, 0.15, 0.2) at room temperature were determine. 3.3.1.dielectric constant and dielectric loss it is observed that the dielectric constant and dielectric loss disperse at high frequency. the dielectric constant increases with increased in cerium substitution, according to the findings. in the low frequency area, it declines dramatically for all compositions with rising frequency and becomes nearly constant in the medium region up to 1.5 ghz. the phenomenon of dispersion, which occurs as a function of the applied field at lower frequencies, is linked to the reduction in dielectric constant with increasing frequency. at higher frequencies, however, similar dispersion effects are not observable. this phenomena in ferrites materials is explained by koop's phenomenological theory and maxwell–wagner interfacial polarization. they proposed that at low frequencies, grain borders are more active and essential than the grains themselves due to space charge polarization, whereas at high frequencies, the opposite is true (junaid et al., 2016). figure 4: (a) dielectric constant vs frequency and (b) dielectric loss vs frequency of ni0.5co0.5cexfe2-xo4 (x= 0.0, 0.05, 0.1, 0.15, 0.2) these theories show that grains are more operational at high frequencies and grain borders at low frequencies are more active. at high frequencies ionic and electronic polarization occurs at grain and grain limits due to the irregular oxygen ion distribution during annealing. this irregular oxygen distribution causes low-frequency interfacial polarization. the strength of polarization decreases as the frequency increases, and the dielectric constant tends to decrease. figure 4 (a) and (b) shows the dielectric constant and dielectric loss respectively. at the octahedral site, the electron exchange takes place between fe3+ and fe2+. electronic hopping reduces the dielectric constant because it does not follow the pattern of the applied alternating field at high frequencies (decker, 2016). the minimum dielectric loss value of 2.6 ghz is observed. 3.3.2.tangent loss and ac conductivity the observed variation in tangent loss is the same as the observed variation in the dielectric constant and the variation in the dielectric loss. in low frequency, the tangent loss is high as hopping electrons are parallel to field’s frequency, but at high frequency hopping journal of materials and physical sciences 1(1), 2020 32 electrons, refuse to obey the applied frequency which causes the tangent loss to decrease after some critical frequencies (sheikh et al., 2019). figure 5 clearly shows that tangent loss is considerable at low frequencies and steadily diminishes as frequency increases, as predicted by koops' phenomenological theory. the reduced tangent loss of nano ferrites is critical in a variety of applications. ac conductivity is the most important characteristic in dielectric material. at room temperature, the ac conductivity of a synthesized ferrite sample with composition ni0.5 co0.5 cex fe2 – x o4 (x=0.0, 0.05, 0.1, 0.15, and 0.2) is observed in the range of 1 to 3 ghz frequency. the ac conductivity has the formula: σ ac = t/a(z/)/z/2 + z//2 (8) where "t" represents the thickness of the pellet, a represents the area, and z' and z" represent the real and imaginary impedance, respectively. the ratio of ε′ and ε′′ with loss tangent (tan ś) is described by: tan δ = ε′′/ ε′ (9) the graph below depicts the conductivity of alternating current (sheikh et al., 2019). the figure shows that all samples show the same behavior at low frequency (increasing trend). the maxwell wagner heterogeneous model can also be used to explain the frequency dependence of ac conductivity. the structure of dielectric materials, according to this hypothesis, is made up of two layers. the first layer is made up of well-conducting grain, whereas the second layer is made up of grain boundaries that are very resistant. highly resistive grain boundaries become more active at low frequencies, preventing electron transfer between fe3+ and fe2+ cations. as a result, the ac conductivity decreases. conducting grains becomes active at increasing frequencies of an alternating field, and electron hoping between fe3+ and fe2+ cations increases. ac conductivity rises in lockstep with hopping (kamran & anis-ur-rehman, 2020). different parameters like dielectric constant, dielectric loss and tangent loss are given in the table 4. table 4 different dielectric parameters of ni0.5co0.5cexfe2-xo4 (x= 0.0, 0.05, 0.1, 0.15, 0.2) parameters frequency x=0.0 x=0.05 x=0.10 x=0.15 x=0.20 dielectric constant 1mhz 10.72 7.6 10.11 5.57 5.2 1ghz 4.21 3.3 3.31 3.49 3.11 2.5ghz 3.68 2.98 2.86 3.05 2.73 3ghz 3.9 3.21 3.2 3.24 2.9 dielectric loss 1mhz 5.078 3.75 5.37 2.21 1.78 1ghz 0.098 0.17 0.1 0.06 0.05 2.5ghz 0.318 0.06 0.087 0.15 0.19 3ghz -0.011 -0.008 0.14 0.07 0.032 tangent loss 1mhz 0.473 0.49 0.53 0.39 0.34 1ghz 0.023 0.05 0.03 0.02 0.017 2.5ghz 0.086 0.02 0.03 0.05 0.071 3ghz -0.003 -0.0024 0.043 0.02 0.011 saira yasmeen, h. m. noor ul huda khan asghar, zaheer abbas gilani, muhammad khalid 33 figure 5: (a) tangent loss vs frequency and (b) ac conductivity vs frequency of ni0.5co0.5cexfe2-xo4 (x= 0.0, 0.05, 0.1, 0.15, 0.2) 3.3.3.real and imaginary impedance impedance plays a vital role in the dielectric properties of the material. figure 6 (a) and (b) represents the real and imaginary impedance vs. log f. figure 6: (a) log f vs real impedance and (b) log f vs imaginary impedance of ni0.5co0.5cexfe2-xo4 (x= 0.0, 0.05, 0.1, 0.15, 0.2) the frequency applied influenced the real and imaginary impedance strictly. real and imaginary impedance parts can be calculated using formulas z/ = r = /z/ cos θz (10) z// =x = /z/ sinθz (11) the research reveals that applied frequency has an inverse relationship with real and imaginary impedance, implying that as frequency rises, imaginary and real impedance fall. all sample impedance curves merge at higher frequency. the constant higher frequency impedance is attributed to release of space charges. these space charges are formed as a result of the concentration differential as well as the inhomogeneity of the applied field. the concentration difference and inhomogeneity of the applied field combines the spatial charges at the grain limits. the reduction in the real and imaginary impedance manifests improved conductivity if the frequency applied is increased (parveen et al., 2019). 3.3.5 real and imaginary modulus the real and imaginary modulus qualities can be used to explain the purpose of grains and grains boundaries on a certain frequency range. journal of materials and physical sciences 1(1), 2020 34 figure 7: (a) real modulus vs frequency and (b) imaginary modulus vs frequency of ni0.5co0.5cexfe2-xo4 (x= 0.0, 0.05, 0.1, 0.15, 0.2) different values of dielectric parameters like ac conductivity, z', z'', m' and m'' are given below in table 5. table 5 various parameters of dielectric of ni0.5co0.5cexfe2-xo4 (x= 0.0, 0.05, 0.1, 0.15, 0.2) the following formulas can be used to calculate the real and imaginary modulus. m/ = €/ / (€/2 + €//2) (12) m// = €// / (€/2 + €//2) (13) figure 7 (a) and (b) shows that the frequency has a direct relationship with the real and imaginary modulus. the real and imaginary modulus have smaller values at low frequencies, and the modulus increases as the frequency rises. the greatest modulus values are found at 3 ghz frequency (rodrigues & mcphaden, 2014). the m' and m" have tiny values and little fluctuation at low frequencies, as shown in the figure. two opposed peaks (trough for real impedance and crest for imaginary impedance) are found due to relaxation phenomena (frequency dependent variation in conductivity). variations in dopant concentration cause a shift in the peak frequency (khan et al., 2020). the different values of m' and m" for the frequency ranges of 1mhz, 2mhz, 2.5 ghz, and 3ghz were analyzed, and it can be seen that the ac conductivity, real parts of modulus (m/), imaginary parts of modulus (m/), real parts of impedance (z/), and imaginary parts of impedance (z/) vary in a inhomogeneous manner. frequency concentrations x=0.0 x=0.05 x=0.1 x=0.15 x=0.2 ac conductivity 1 mhz 2.818×10-4 2.232×10 -4 2.1402×104 1.484×10-4 1.305×10-4 1 ghz 5.858×10-3 1.502×10-2 6.842×10-3 4.231×10-3 3.654×10-3 2.5 ghz 4.856×10-2 9.59×10-3 1.7228×10-2 2.97×10-2 3.680×10-2 3 ghz 1.621×10-4 3.53×10-3 2.3387×10-2 1.8153×10-2 8.358×10-3 z'/ohm 1 mhz 1.912×104 3.292×104 2.0047×104 2.9345×104 3.6111×104 1 ghz 2.306 8.454 3.74 2.153 2.166 2.5 ghz 3.607 0.983 1.852 2.324 4.162 3 ghz 8.02×10-3 0.2252 1.5024 1.1374 0.6073 z''/ohm 1 mhz 3.9724×104 5.605x104 4.4593x104 6.9315x104 7.9029x104 1 ghz 1.061×102 1.267×102 1.2508×102 1.2073×102 1.3024×102 2.5 ghz 4.5985×101 5.421 5.5455×101 5.2653×101 5.6770×101 3 ghz 3.7641×101 4.275 4.2869×101 4.2349×101 4.5617×101 m' 1 mhz 7.7161×10-2 1.089×10-1 8.6618×10-2 1.3463x10-1 1.535×10-1 1 ghz 2.073×10-1 2.475×10-1 2.4432×10-1 2.3584×10-1 2.545×10-1 2.5 ghz 2.2376×10-1 2.638×10-1 2.6984×10-1 2.5621×10-1 2.763×10-1 3 ghz 2.1934×10-1 2.49×10-1 2.4980×10-1 2.477×10-1 2.658×10-1 m'' 1 mhz 3.7145×10-2 6.395×10-2 3.8939×10-2 5.7001×10-2 6.529×10-2 1 ghz 4.503×10-3 1.652×10-2 7.306×10-3 4.421×10-3 4.232×10-3 2.5 ghz 1.7552×10-2 4.79×10-3 9.01×10 -3 1.131×10-2 2.025×10-2 3 ghz 4.67×10-5 1.312×10-3 8.755×10-3 6.628×10-3 3.538×10-3 saira yasmeen, h. m. noor ul huda khan asghar, zaheer abbas gilani, muhammad khalid 35 4. conclusions the nano-crystalline ferrite synthesized with the general formula ni0.5co0.5cexfe2– xo4 (x=0.0, 0.05, 0.15, 0.2). the ce3+ substitution clearly affects the structural and electrical characteristics. the crystalline dimensions of nano ferrites are calculated using the debye scherer formula and are between 8 nm and 11 nm. it was discovered that crystalline size does not changes uniformly with doping. the calculations demonstrate that grain sizes correlate with xrd data, confirming the crystalline size of the manufactured samples. the observations show that the extreme peaks were identified at 2θ = 35 with (311) hkl utility, which are the optimum peaks for spinel ferrite nano particles. there is a similarity of indexed peaks (220) (311) (400) (531) with a spinel structure. the lattice constant is observed as a growing trend. the increase in doping concentration also increases cell volume. the systematic variations and chemical effects of fourier transform infrared spectroscopy (ftir) are identified in octahedral and tetrahedral sites, there is a constant force range of 1.441 x 105 to 1.460 x 105 and 2.60 x 105 to 2.618 x 105, respectively. the range of the octahedral radii is between 0.715 and 0.769 and the tetrahedral radii between 0.442 and 0.489. dielectric properties are observed in the 1 mhz to 3 ghz frequency range. dielectric constant, dielectric loss and tangent loss is seen in the dielectric study to decrease in trend. the impedance of the composed spinal ferrite is strengthened by increasing the doping concentration of rare earth ion. this is owing to the fact that as frequency rises, impedance decreases. because of the hopping mechanism, ac conductivity spectra show continuous behavior at low frequencies but dispersion at high frequencies. the study of the real and imagination modulus shows that the effect of low-frequency grain boundaries is high. the excellent electrical properties of ferrites ensure that these materials are used for pharmacological delivery, cancer treatment, high frequency applications, microwave applications, storage and semiconductor devices. acknowledgement the authors are grateful to the oric of the balochistan university of information technology, engineering, and management sciences (buitems) in quetta, pakistan, for their assistance and financial support in completing this research project in the department of physics. references al-hilli, m. f., li, s., & kassim, k. s. 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(2017). five-component domino synthesis of tetrahydropyridines using hexagonal pbcr x fe 12− x o 19 as efficient magnetic nanocatalyst. research on chemical intermediates, 43(11), 6155-6165. https://doi.org/10.52131/jmps.2023.0401.0033 20 journal of materials and physical sciences volume 4, number 1, 2023, pages 20 31 journal homepage: https://journals.internationalrasd.org/index.php/jmps exploring study of magnetic and electrical properties of tl3+ doped co0.5ni0.5fe2o4 spinel ferrites touseef ahmad1, m.u. islam1*, i.h gul2, mutawara mahmood baig3, m. ajmal1 1 institute of physics, bahauddin zakariya university, multan, pakistan 2 school of chemical & materials engineering (scme), nust, islamabad, pakistan 3 school of chemistry and chemical engineering, yangzhou university, yangzhou, jiangsu, 225009 p. r. china article info abstract article history: received: february 26, 2023 revised: april 29, 2023 accepted: may 06, 2023 available online: june 28, 2023 co0.5ni0.5fe2-xtlxo4 (x=0, 0.05, 0.1, 0.15, and 0.2) spinel ferrites were prepared via the sol-gel technique. the xrd analysis revealed a single-phase spinel structure. the lattice constant ‘a’ increased from 8.223-8.269å with doping of tl+3 due to larger ionic radii of tl+3 than fe+3 ions. the mass susceptibility at 300k decreased from 7.46 x 10-3-4.15 x 10-3 cm3/g due tothe weakening of ab interactions followed by a decrease in curie temperature from 453k to 408k. the electrical permittivity follows the maxwell-wagner model and koop’s theory. the dc resistivity of ferrites at 300k increased from 1.82x109-9.23x109 ω-cm with increasing tl+3 contents due to increased hopping lengths. the activation energy obtained from arrhenius plots increased from 0.126 to 0.131ev, increasing tl+3contents. keywords: sol-gel auto combustion spinel ferrites x-ray diffraction magnetic susceptibility dielectric properties resistivity © 2023 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: dr.misbahulislam@bzu.edu.pk 1. introduction spinel ferrites have got prime importance due to their versatile properties. these magnetic materials have high resistivity (goldman, 2006; jalaiah, mouli, krishnaiah, babu, & rao, 2019) and low eddy current losses. the nanoparticles of spinel ferrites exhibit novel properties that are useful in biomedical applications. spinel ferrites are low-cost and easy to fabricate for various engineering applications like recording media, microwave absorbers, sensors, etc (kazimierczuk, 2009). amongst the various methods available for the preparation of sol-gel technique is low cost and easy to handle. the homogeneous distribution of nanoparticles is obtained using the sol-gel method (batoo, kumar, & lee, 2009; cullity & graham, 2011). co-ni spinel ferrites have attracted the attention of materials scientists (abdel-latif, 2012; abdul-aziz, abrahem, & khaleel, 2013; asghar et al., 2018; singha, singhb, & dosanjha, 2015; velhal, patil, shelke, deshpande, & puri, 2015) due to high saturation magnetization and curie temperature. since co is more anisotropic (kambale, shaikh, kamble, & kolekar, 2009; ortiz-quiñonez, pal, & villanueva, 2018) compared to ni, co-ni spinel ferrites become superior to other spinels. the substitution of transition metal ions in the co-ni ferrites may augment the magnetic properties. velhal et al.(velhal et al., 2015) reported the ni-doped co spinel ferrites via lowtemperature auto-combustion technique and reported that increasing the ni content in cobalt ferrite decreases the magnetization because of the lower magnetic moment of nickel than cobalt. gaffoor et al.(gaffour & ravinder, 2014) synthesized the co-doped nife2o4 spinel ferrites by the sol-gel route. they reported that increasing the cobalt content in nife2o4 increases the lattice parameter and crystallite size. amirabadizadeh et al.(amirabadizadeh & amirabadi, 2013) synthesized the al-doped ni0.6co0.4fe2o4 spinel ferrites via the sol-gel route. they reported that by increasing the content of al+3 (0-0.7) in https://journals.internationalrasd.org/index.php/jmps mailto:dr.misbahulislam@bzu.edu.pk touseef ahmad, m.u. islam, i.h gul, mutawara mahmood baig, m. ajmal 21 ni-co spinel ferrites, the crystallite size decreases from 29nm to 10nm. similarly, the saturation magnetization decreases from 61-10 emu/g with increasing al+3 content in ni-co spinel ferrites. farid et al.(m. farid et al., 2015)reported the effect of nd on the electrical properties of ni-co spinel ferrites prepared by the sol-gel route and observed that both the dc resistivity and activation energy increase with nd doping in ni-co spinel ferrites. in the present work, tl-substituted co0.5ni0.5fe2o4ferrites are prepared by the sol-gel technique. to the best of our knowledge, the tl-doped co-ni spinel ferrites have yet to be reported frequently in the literature. there was a need to investigate the tl-doped co-ni ferrites. 2. experimental procedure thallium (tl) doped co0.5ni0.5fe2o4 spinel ferrites were prepared via the sol-gel autocombustion method. analytical grade starting materials were used; fe(no3)3.9h2o, tlno3, ni(no3)3.6h2o, co(no3)3.6h2o, and citric acid. stock solutions of all the nitrate salts and citric acid were prepared in 100 ml of distilled water in a beaker. these stock solutions were added to a 1000 ml beaker and stirred at 70oc continuously to obtain a homogeneous solution. ammonium hydroxide was added dropwise in the solution to maintain the ph =7. after complete evaporation, a thick gel is formed; stirring was stopped, and the gel was burnt at about 400oc by the auto combustion process. the complete combustion ofthe ash gives ferrite powder (be implemented from june; kumar et al., 2015; sajjadi, 2005). the ash was ground and sintered at 1050oc for 5 hours in a box furnace. the following fig. (1) shows the steps for the sol-gel method. stirring stirring + heating ammonia solution at 70oc drop wise heated at 400oc figure 1: flow chart of sol-gel process 2.1. characterizations techniques 2.1.1. x-ray diffraction x-ray diffraction is used to determine the phase purity of samples; d-values, lattice constant, and hopping length may be determined from xrd data. bragg's law is used to determine the d-values of a specimen. bragg’s law is given below (de almeida et al.; suryanarayana, norton, suryanarayana, & norton, 1998): 2𝑑𝑠𝑖𝑛𝜃 = 𝑛𝜆 (1) where 𝜃 is the bragg angle, and d is the inter-planer spacing. the lattice constant is determined by using the following equation (kumar et al., 2015): stock solutions of nitrate salts + stock solution of citric acid homogeneous solution gel format ion auto combustio n evaporation ground for 30 mints ash formation ferrite powder journal of materials and physical sciences 4(1), 2023 22 𝑎 = 𝜆 2𝑠𝑖𝑛𝜃 √ℎ2 + 𝑘2 + 𝑙2 (2) where 𝑎= lattice constant, λ= 1.54å and 𝜃= bragg’s angle, and hkl are miller indices. the volume of the spinel unit cell is determined by using the formula: 𝑉 = 𝑎3(å3) (3) the distance between magnetic ions or hopping length is calculated by using the formulae (babbar, 1997): 𝐿𝐴 = 0.25 𝑎 √3 (4) 𝐿𝐵 = 0.25 𝑎 √2 (5) where la= hopping length in a-site, lb= hopping length in b-site, and ‘𝑎’ is lattice constant. 2.1.2. magnetic susceptibility the term magnetic susceptibility (χ) of magnetic materials is defined as the ratio of magnetization (m) to magnetic field intensity (h) (nikam et al., 2015): 𝜒 = 𝑀 𝐻 (6) the magnetic susceptibility of ferrites also depends on the temperature, called the curie-weiss law. at curie temperature, ferrites' magnetic susceptibility becomes constant, which is paramagnetic (callister jr, 2007). 2.1.3. construction of colpitts oscillator as susceptometer the lc oscillator can be used to find the magnetic susceptibility. the tank circuit of lc oscillators consists of two capacitors and an inductor. when the oscillator works, the solenoid's magnetic field is set up. when a magnetic material is put in the solenoid, it gets magnetized. the magnetic field strength is increased, and hence the inductance of the solenoid is increased (kazimierczuk, 2009; properties). the frequency of the lc oscillator is determined as (boylestad & nashelsky, 2009): 𝑓 = 1 2𝜋√𝐿𝐶 (7) since the capacitance (c) is constant, the frequency of lc oscillator is inversely proportional to the square root of inductance: 𝑓 ∝ 1 √𝐿 (8) the inductance of the solenoid is increased when the ferrite sample is placed in the solenoid field, hence the frequency of lc oscillator is decreased. the circuit diagram for the colpitts oscillator as susceptometer is shown in fig.(2). the susceptometer was constructed using the following circuit diagram to measure the magnetic susceptibility. the tank circuit of the colpitts oscillator consists of two capacitors and an inductor in the form of a solenoid. the frequency of the colpitts oscillator is determined as follows: 𝑓 = 1 2𝜋√𝐿𝐶𝑒𝑞 (9) where, 𝐶𝑒𝑞 = 𝐶1𝐶2 𝐶1+𝐶2 (10) touseef ahmad, m.u. islam, i.h gul, mutawara mahmood baig, m. ajmal 23 figure 2: colpitts oscillator as susceptometer circuit diagram the values of c1 and c2 were 0.33µf, and the solenoid had 550 turns twisted on ceramic paper with copper wire gauge 26 swg. the length of the solenoid was 5cm, and the volume was 55 cm3. the op-amp as inverting amplifier was used for oscillations because the tank circuit provides the 180o phase inversion, and the 180o phase inversion is also provided by inverting amplifier. thus the total phase inversion is 360o, which satisfies the barkhausen criterion condition for oscillations. when the sample is inserted into the magnetic field of the solenoid, the frequency changes; this change in frequency was converted into magnetic susceptibility using the following equation (figueroa et al., 2012; vannette, 2009): ∆𝑓 𝑓 = − 1 2 𝑉𝑆 𝑉𝐶 4𝜋𝜒 (11) where f = frequency of oscillator without sample, vs = volume of sample, vc= volume of a coil (solenoid), χ = magnetic susceptibility. the ∆f changes in the oscillator frequency: ∆𝑓 = 𝑓 / − 𝑓, where f/ = oscillator frequency with a sample. the change in frequency (∆𝑓) with the ferrite sample is negative. this negative sign is canceled with the negative sign of the right-hand side of equation (7); hence the magnetic susceptibility is positive for ferrites. the volume magnetic susceptibility (χ) of spinel ferrites was determined by: 𝜒 = − 2∆𝑓 𝑓 𝑉𝐶 4𝜋𝑉𝑆 (12) the volume magnetic susceptibility (dimensionless) is converted to mass susceptibility (χm) as (cullity & graham, 2011): 𝜒𝑚 = 𝜒 𝜌 ( 𝑚3 𝑘𝑔 ) (13) 𝜒𝑚 = 𝜒 𝜌 𝑋 1000 4𝜋 ( 𝑐𝑚3 𝑔 ) (14) journal of materials and physical sciences 4(1), 2023 24 where ρ= mass/volume = bulk density of the specimen. the mass susceptibility (χm) was converted into molar susceptibility (χmol) as (raghasudha, ravinder, & veerasomaiah, 2013): 𝜒𝑚𝑜𝑙 = 𝜒𝑚 𝑋 𝑀𝑜𝑙𝑒𝑐𝑢𝑙𝑎𝑟 𝑤𝑒𝑖𝑔ℎ𝑡 ( 𝑐𝑚3 𝑚𝑜𝑙 ) (15) 2.1.4. dielectric study the capacitance and dissipation of spinel ferrite specimens were measured through lcr model 8108 with a frequency range 20 hz to 1 mhz. the capacitance of the specimen was converted to dielectric constant (ε/) by using the following formula (pervaiz & gul, 2012): ′ = 𝐶𝑡 𝜀𝑜𝐴 (16) where ε’ = dielectric constant, εo= permittivity of free space (8.85 x 10-12 f/m), c= capacitance of the sample, and t = pellet thickness. the dielectric loss was measured from the following equation: ′′ = ′ 𝑡𝑎𝑛𝛿 (17) where ε’’ = dielectric loss and tan𝛿 = loss tangent. 2.1.5. resistivity measurement the well-known two-probe method was used to find the resistivity of spinel ferrites. for this purpose, the keithley source meter model 2400 was used. the temperature varied from 300 to 520k during the measurements. the following relation was used to find the resistivity of spinel ferrites (arshad et al., 2018): 𝜌 = 𝑅 𝐴 𝑡 (18) where ρ= resistivity of pellet, r= resistance of pellet, a= area of the pellet, and t = thickness of the pellet. the resistance (r) was measured from the slope of the i-v graph. 2.1.6. activation energy the activation energy of spinel ferrites was determined by using the arrhenius equation given below (ramarao et al., 2018): 𝜌 = 𝜌𝑜 exp ( 𝐸𝑎 𝑘𝐵𝑇 ) (19) where ρ is the resistivity of spinel ferrite at temperature t, ρo= resistivity of the sample at room temperature, ea = activation energy, and kb = 1.38066 x 10-23 j/k (boltzmann’s constant). by solving the equation (17), the activation energy was determined as(devmunde et al., 2016): 𝐸𝑎 = 0.1987 𝑋𝑠𝑙𝑜𝑝𝑒𝑜𝑓𝑡ℎ𝑒 𝑔𝑟𝑎𝑝ℎ (𝑒𝑉) (20) 3. results and discussion 3.1. x-ray diffraction fig. 3 shows the xrd patterns of co0.5ni0.5tlxfe2-xo4 spinel ferrites with x= 0.0, 0.05, 0.1, 0.15, and 0.2. the xrd analysis of tl-doped coni ferrites prepared by sol-gel auto combustion method and sintered at 1050oc for 5hours revealed the cubic spinel structure. the peaks were identified by comparing the d-values with jcpds card no. 21-1152. five peaks characteristic of the fcc structure were observed (220). (311), (400), (422), and (333) with no extra peak that revealed the single-phase cubic spinel structure of tl-doped coni ferrites (asghar et al., 2018). this is because the tl is soluble in the lattice, which is substituted in small amounts with interval x=0.05. since the minute amount of tl is substituted, no shift in the xrd peaks is observed even though the ionic radius of tl is larger than fe. the lattice constant of tl doped ferrites and unit cell volume are given in table 1. touseef ahmad, m.u. islam, i.h gul, mutawara mahmood baig, m. ajmal 25 20 25 30 35 40 45 50 55 60 0 100 200 300 400 500 600 700 in te n s it y ( a .u .) 2 (degrees) (220) (311) (400) (422) (333) x=0.2 x=0.15 x=0.1 x=0.05 x=0 figure 3: xrd patterns of co0.5ni0.5tlxfe2-xo4 (x=0.0-0.2) table 1 xrd parameter of ferrite compostions with varied thallium content thallium content (x) ferrite composition a(å) unit cell volume (å3) la (å) lb(å) 0.0 co0.5ni0.5fe2o4 8.223 556.02 3.561 2.907 0.05 co0.5ni0.5fe1.95tl0.5o4 8.235 558.46 3.566 2.911 0.10 co0.5ni0.5fe1.9tl0.1o4 8.245 560.5 3.570 2.915 0.15 co0.5ni0.5fe1.85tl0.15o4 8.258 563.15 3.576 2.919 0.2 co0.5ni0.5fe1.8tl0.2o4 8.269 565.4 3.581 2.923 the lattice constant of co-ni ferrites increased from 8.223 to 8.269å with the doping of tl+3 ions in coni ferrites because of the larger ionic radius of the tl+3 ions (1.025å) than that of fe+3 ions (0.67å) as shown in fig (4). 0.00 0.05 0.10 0.15 0.20 8.22 8.23 8.24 8.25 8.26 8.27 a (å ) tl content (x) journal of materials and physical sciences 4(1), 2023 26 figure 4: variation of lattice constant ‘a’ vs tl concentration for co0.5ni0.5tlxfe2-xo4 (x=0.0-0.2) ferrites lattice constantly followed vegard’s law (suryanarayana et al., 1998). the hopping lengths la and lb were calculated using equations (4) and (5) and are listed in table 1. it is observed that the hopping lengths la and lb increase due to lattice distortion produced when tl is substituted. 3.2. magnetic susceptibility the temperature-dependent magnetic susceptibility of tl-doped co-ni spinel ferrites was determined through the colpitts oscillator susceptometer at 10 khz frequency in the temperature range 290-520k.fig.5shows the temperature-dependent magnetic susceptibility of tl-doped co-ni ferrites.fig.5 shows that the maximum magnetic susceptibility is 7.46x10-3 cm3/g for a sample with x=0, and the minimum magnetic susceptibility is for the specimen with x=0.2. the magnetic susceptibility continuously decreases with increasing tl contents in ferrite. there are two sublattices in spinel ferrite called a and b-sublattice. both the sublattices are antiferromagnetically aligned. the total magnetization (m) of spinel ferrites is given by equation (shinde, 2016): 𝑀 = 𝑀𝐵 − 𝑀𝐴 (21) where mb= magnetization of b-sublattice and ma= magnetization of a-sublattice. 300 350 400 450 500 550 0.000 0.002 0.004 0.006 0.008  ( c m 3 /g ) temperatute (k) x=0 x=0.05 x=0.1 x=0.15 x=0.2 figure 5: magnetic susceptibility vs temperature for co0.5ni0.5tlxfe2-xo4 (x=0.00.2) according to neel's theory of ferrimagnetism, the a-b interactions are strongest in spinel ferrites than in a-a and b-b interactions. the tl is non-magnetic and prefers b-sites due to its larger ionic radius (1.03å) (goldman, 2006). by increasing the content of tl+3 ions in co-ni spinel ferrite the magnetization of b-sublattice (mb) decreased. hence the total magnetization (m) is decreased. thus due to the decrease of magnetization, the magnetic susceptibility is decreased with increasing content of tl+3 ions. the magnetic susceptibility at room temperature, effective magnetic moments, and curie temperature of ferrite specimens are given in table 2. the curie temperature of co-ni ferrite decreases with the increasing content of tl+3 ions. the a-b interactions decrease with increasing tl content in coni ferrites which causes the decrease in magnetization. whereas the curie temperature decreases with tl contents. fig.5 also shows that the magnetic susceptibility decreases with temperature. at lower temperatures, ferrites' thermal atomic vibrations are small, and the coupling of magnetic forces is large. in ferrites, the magnetic moments are aligned due to coupling magnetic forces. the susceptibility is high at lower temperatures due to large touseef ahmad, m.u. islam, i.h gul, mutawara mahmood baig, m. ajmal 27 coupling magnetic forces. when the temperature is increased, the thermal atomic vibrations are increased and dominate the magnetic coupling forces that disturb the alignment of domains in ferrites. thus the magnetic susceptibility decreases with temperature. the magnetic susceptibility is dropped to a minimum value above curie temperature. the domains are oriented randomly above curie temperature and the ferrite sample becomes paramagnetic (callister jr, 2007; kazimierczuk, 2009). fig.6 (a) & (b) show the plots of tl content vs magnetic susceptibilities at 300k and curie temperatures, respectively. table 2 magnetic susceptibility vs temperature content of prepared samples composition cm3/g) curie temp. tc (k) µeff mol(cm 3/mol) co0.5ni0.5fe2o4 7.46x10 -3 453 63.47 1.749 co0.5ni0.5fe1.95tl0.5o4 6.63 450 60.78 1.604 co0.5ni0.5fe1.9tl0.1o4 5.80 438 57.71 1.446 co0.5ni0.5fe1.85tl0.15o4 4.97 423 54.21 1.276 co0.5ni0.5fe1.8tl0.2o4 4.15 408 50.27 1.097 0.00 0.05 0.10 0.15 0.20 0.004 0.005 0.006 0.007 0.008 0.00 0.05 0.10 0.15 0.20 410 420 430 440 450 460  ( c m 3 /g ) tl content (x) (a) t c (k ) tl content (x) (b) figure 6: (a) plot of tl content vs magnetic susceptibility at 300k for co0.5ni0.5tlxfe2-xo4 (x=0.0-0.2) ferrites (b) plot of tl content vs curie temperature of co-ni ferrites the effective magnetic moment (µeff) of co0.5ni0.5tlxfe2-xo4 (x=0.0-0.2) spinel ferrites was calculated using the following formula [28, 34](zatsiupa et al., 2014): µ𝑒𝑓𝑓 = √ 3𝑘𝐵 𝑁𝐴µ𝐵 2 𝑋 √𝜒𝑚𝑜𝑙 𝑇(µ𝐵 ) (22) µ𝑒𝑓𝑓 = 2.828√𝜒𝑚𝑜𝑙 𝑇(µ𝐵 ) (23) where µeff = effective magnetic moment in bohr magnetrons, kb= boltzmann constant (1.38 x 10-16 erg/k), na= avogadro’s number (6.022 x 1023), and µb= bohr magnetron (9.274 x 10-21 erg/g). the effective magnetic moment was observed to decrease with doping non-magnetic (tl+3) ions in co-ni spinel ferrites, as listed in table2. 3.3. dielectric constant the frequency-dependent dielectric properties were determined in the frequency range from 20hz to 1mhz using equations (16) & (17). fig.(7a) shows the plot of dielectric constant vs frequency. the dielectric constant (ε/) and dielectric loss (ε//) were observed to decrease with frequency and also observed to decrease with the concentration of tl+3 ions. the interfacial polarization and conductivity of ferrites are due to the presence of fe+3 and fe+2 cations on the b-sites. with increasing the tl+3 ions in co-ni ferrites, the content of fe+3 ions decreases on the b-sites because the tl+3 ions prefer b-sites due to their larger journal of materials and physical sciences 4(1), 2023 28 ionic radius. thus the interfacial polarization is reduced, causing the dielectric constant's value to drop (m. t. farid, ahmad, murtaza, ali, & ahmad, 2016). according to the maxwell-wagner model (1951) (batoo et al., 2009), ferrites consist of two layers; the conducting grains and highly resistive grain boundaries. at lower frequencies, the resistive grain boundaries are more active and resist electrons hopping between fe+2 and fe+3 cations, causing interfacial polarization. at higher frequencies, the conducting grains are more active and allow the hopping of electrons from fe+2 to fe+3 cations; thereby, polarization decreases. thus, the dielectric constant is decreased at higher frequencies (batoo et al., 2009; devmunde et al., 2016). according to maxwell-wagner theory, the dielectric loss is also reduced due to decreased space charge polarization, as shown in fig. (7b). 0.00 2.50x10 5 5.00x10 5 7.50x10 5 1.00x10 6 0 200 400 600 800 1000 1200 1400 0.00 2.50x10 5 5.00x10 5 7.50x10 5 1.00x10 6 0 200 400 600 800  / frequency (hz) x=0 x=0.05 x=0.1 x=0.15 x=0.2 (a) 0 20000 40000 60000 80000 100000 0 200 400 600 800 1000 1200 1400  / frequency (hz)  // frequency (hz) x=0 x=0.05 x=0.1 x=0.15 x=0.2 (b) 0.0 2.0x10 4 4.0x10 4 6.0x10 4 8.0x10 4 1.0x10 5 0 200 400 600 800  // frequency (hz) figure 7: (a) dielectric constant vs frequency for tl doped co0.5ni0.5fe2o4 ferrites (b) dielectric loss vs frequency for tl doped co0.5ni0.5fe2o4 ferrites 3.4. dc resistivity fig. (8) shows the arrhenius resistivity plots for tl doped co0.5ni0.5fe2o4 spinel ferrites measured by two probe methods. the resistivity of co-ni spinel ferrites was observed to increase with the doping of tl+3 cations (fig. (9a)). 2.0 2.5 3.0 3.5 12 14 16 18 20 22 24 in  (  -c m )→ t/1000 (k) → x=0 x=0.05 x=0.1 x=0.15 x=0.2 figure 8: arrhenius plots for co0.5ni0.5tlxfe2-xo4 ferrites touseef ahmad, m.u. islam, i.h gul, mutawara mahmood baig, m. ajmal 29 according to verway’s mechanism(arshad et al., 2018), the conductivity of ferrites is due to the presence of fe+2 and fe+3 cations on the b-site. as the tl+3 contentsare increased, the concentration of fe+3 cations decrease on the b-sites. the hopping length in b-site (lb) was found to increase with the doping of tl+3 ions, as mentioned in table 1. thus the hopping of electrons between fe+2 and fe+3 cations decreases. so the resistivity of coni spinel ferrite is increased with doping tl+3. the resistivity of tl-doped co0.5ni0.5fe2o4 was also observed to decrease with increasing temperature, confirming these ferrites' semiconducting behavior (bhandare, jamadar, pathan, chougule, & shaikh, 2011; pervaiz & gul, 2012). the activation energy of spinel ferrites was determined from arrhenius plots as shown in fig.(9b). the activation energy of co-ni spinel ferrite increases with the doping of tl+3 ions according to verway’s hopping mechanism (devmunde et al., 2016)—the plot of activation energy vs. tl contents follow the room temperature resistivity as shown in fig.(9b). 0.00 0.05 0.10 0.15 0.20 0.25 2.0x10 9 4.0x10 9 6.0x10 9 8.0x10 9 1.0x10 10 0.00 0.05 0.10 0.15 0.20 0.25 0.126 0.128 0.130 0.132  (  c m ) tl content (x) (a) e a ( e v ) composition of tl (x) (b) figure 9: (a) variation in resistivity vs tl content for co0.5ni0.5tlxfe2-xo4 ferrites (b) plot of activation energy vs tl content for co0.5ni0.5tlxfe2-xo4 ferrites conclusions the lattice constant was observed to increase from 8.223 to 8.269 å.the hopping length in the a-sites was found to increase from 3.561 to 3.581 å, andin the b-sites increased from 2.907 to 2.923å with doping tl+3 ions.the magnetic susceptibility at room temperature decreased from 7.46 x 10-3 to 4.15 x 10-3 cm3/g, increasing the tl content from 0 to 0.2. the effective magnetic moment was found to decrease from 63.47 to 50.27 b with doping tl+3 ions in co-ni spinel ferrites. the curie temperature decreases from 453 to 408k with increasing the tl contents in co-ni ferrites.according to the maxwell-wagner model, the dielectric constant and dielectric loss decrease with frequency. the dielectric constant decreases at 20 hz from 1295 to 190 with increasing the contents of tl from 0 to 0.2.the dc resistivity of tl-doped co-ni ferrites increases from 1.82 x 109 to 9.23 x109ω-cm with increasing the contents of tl from 0 to 0.2. the activation energy was observed to increase from 0.126 to 0.131 ev and follows room temperature resistivity. reference abdel-latif, i. a. 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(2014). magnetization, magnetic susceptibility, effective magnetic moment of fe3+ ions in bi25feo39 ferrite. journal of solid state chemistry, 212, 147-150. https://doi.org/10.52131/jmps.2021.0201.0014 33 journal of materials and physical sciences volume 2, number 1, 2021, pages 33 44 journal homepage: https://journals.internationalrasd.org/index.php/jmps structural elucidation and magnetic behavior evaluation of nddoped nickel-cobalt spinel ferrites muhammad waqar1, a. i. aljameel2* 1 institute of physics, the islamia university of bahawalpur, bahawalpur-63100, pakistan 2 department of physics, college of science, imam mohammad ibn saud islamic university (imsiu), riyadh 11623, saudi arabia article info abstract article history: received: april 08, 2021 revised: may 14, 2021 accepted: june 28, 2021 available online: june 30, 2021 nano ferrites crystals of ni0.4co0.6ndxfe2-xo4 for 0.00 ≤ x ≤ 0.08 with step size of 0.02 were synthesized by sol gel technique with annealing at 950 oc for 6 hours. spinel phase along with a secondary phase for nd concentration x ≥ 0.04 due to formation of ndfeo3 was observed in xrd patterns. lattice constant and grain size were found in decreasing trend with increasing concentration of nd as compared to that of undoped nickel cobalt ferrites. x-ray density and porosity both were increased with increasing concentration of neodymium. two characteristics frequency bands were observed in the range of 400cm-1 to 550 cm-1 which showed successful formation of spinel structure. it is also the evidence of metaloxygen bonding at octahedral and tetrahedral sites in spinel ferrites. also, bands for carbon-hydrogen, carboxyl group, carbon-oxygen stretching and iron-cobalt alloys were observed in the ftir spectra. by using these values of characteristics frequencies, octahedral and tetrahedral radii were calculated and found in decreasing trend with increasing concentration. force constants are increasing with increase in neodymium concentration. saturation magnetization, coercivity and remanence values were calculated from the m-h loops. saturation magnetization showed the decreasing behavior with increase in neodymium concentration. coercivity showed increasing values as compared to the base sample and also showing reciprocal relation with saturation magnetization. magnetic moment is decreasing with increase in neodymium concentration. keywords: xrd ftir magnetic properties coercivity remanence ratio © 2021 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: jameel@imau.edu.sa 1. introduction in today’s world we are surrounded by magnetic materials which occurs naturally as well as in many technologies. they have a variety of applications which encompass vast range of fields from computer technology, audio, video applications, telecommunication technology, transportation and energy supply. automotive industry uses them in their sensory applications and electric motors, medical imaging and stealthy aircrafts also make use of magnetic materials. over the years, the production, characterization and application of nanoparticles have gained prominence due to the immense potential present in its application in the environmental, electronics and biomedical fields. in this context, the special properties related to manufacturing processes make nanoparticles a fertile field for technological applications. many researchers have studied different properties of spinel ferrites due to their importance in a wide variety of fields (pardavi-horvath, 2000). https://journals.internationalrasd.org/index.php/jmps mailto:jameel@imau.edu.sa muhammad waqar, a. i. aljameel 34 the influence of neodymium (nd) substitution on the dielectric, electrical and structural properties of nickel cobalt crystals with composition nixco1-xndyfe2-yo4 (0.00 ≤ x ≤ 1.00 and 0.00 ≤ y ≤ 0.10) was studied by m. t. farid et. al using sol gel method. secondary phase of iron neodymium oxide (ndfeo3) was also observed along with the spinel phase when y≥0.06. due to greater ionic radius of neodymium as compared to iron, a trivial increase in lattice parameter was also detected and neodymium substitution restricted the grain growth. it was observed that dc resistivity increased with the increase in neodymium concentration. also rise in temperature led to drop in dc resistivity thus proving the semiconducting materials. the ac-conductivity, dielectric loss (tan δ) and dielectric constant were reduced because of neodymium doping. due to smaller values of conductivity at room temperature these prepared compositions can be used for the microwave applications that need insignificant eddy currents. the reduction in dielectric constant is attributed to the decrease in the internal viscosity of the samples and this can be explained based on space charge polarization. (m. farid et al., 2015). in another paper m. t farid et. al discuss the structure, dielectric and electric properties of different composition by using the sol gel technique. x-ray diffraction analysis revealed that nixco1-xpryfe2-yo4 (0.00 ≤ x ≤ 1.00 and 0.00 ≤ y ≤ 0.10) samples clearly indicate formation of cubic spinel crystals. in the last three samples secondary phase was also identified. lattice constant exhibited increase from 8.363å to 8.384 å with rising pr concentration. dc resistivity at room temperature of ferrites nixco1-xpryfe2-yo4 was increased with increase in praseodymium concentration. the introduction of pr³⁺ replacement with fe³⁺ caused a minor rise in lattice parameter because of greater ionic radius of the doping ions. the grain growth was hindered by doping of praseodymium. temperature dependent direct current electrical resistivity was observed to decrease as the temperature increased which indicated semi-conductor behavior of the samples. these prepared compositions can also be utilized in microwave communication due to low values of dielectric loss and dielectric constant. this synthesized ferrite may be appropriate for applications in the high frequency ranges as having lower values of eddy current losses by the consequence of high dc resistivity values. calculated drift mobility increased with increase in temperature. the dielectric constant value for y = 0.00 were very greater as compared to y = 0.10. in accordance with previous studies, it was observed that the acconductivity, dielectric loss (tan δ) and dielectric constant reduced because of pr3+ substitution (m. t. farid, ahmad, murtaza, ali, & ahmad, 2016). rare earth la3+ material substituted in nickel-cobalt nanocrystalline ferrites were synthesized by sol gel technique. ni0.5co0.5laxfe2-xo4 (where x = 0.025, 0.050, 0.075, 0.100 and 0.125) nanoparticles was carried out at different percentage of la3+ compositions with analytical grade metal nitrate. the fabricated samples have sintered at 400oc and characterized by xrd. scherrer’s formula was used to calculate the particle size. the nanoparticles dimensions of nicofe2o4 with the influence of la3+ was investigated in the range of 23.30 to 32.31 nm range. the crystallite size was observed to be constant with increasing of the lanthanum contains in the compositions. also, the magnetic properties of prepared samples were studied by hysteresis loop terser. we have successfully synthesized nanoparticles of ni0.5co0.5laxfe2-xo4. the xrd pattern of synthesized samples confirmed phase formation of ni0.5co0.5laxfe2-xo4 ferrite. the particle size calculated from x-ray diffraction it showed constant in particle size. from the magnetic properties, it was cleared that the prepared material was soft ferrite. the magnetic saturation changed with substitution of different compositions (kulkarni, bhujbal, & rathod, 2016). 2. materials and methods more than a few approaches have been testified to produce nanocrystalline spinel ferrites; these include powder ceramic technique ( k r i e b l e , l o , m e l i k h o v , & s n y d e r , 2 0 0 6 ) , micro-emulsion method (iqbal & siddiquah, 2008), chemical coprecipitation method (anis-ur-rehman, ansari, mughal, awan, & maqsood, 2012) and soft citrate-gel method (hankare, sankpal, patil, lokhande, & sasikala, 2011). in the current work, sol gel method is used for the preparation of nd doped nickel cobalt nano crystals. the preference to this method was given as it is a simple, speedy and time saving with less energy feeding as compared to other methods. the journal of materials and physical sciences 2(1), 2021 35 impartial of the current work is to prepare nd replaced nickel-cobalt nanocrystal using sol gel technique for exploring the magnetic and structural behavior. nano ferrite of the composition ni0.4co0.6ndxfe2-xo4 (for 0.00 ≤ x ≤ 0.08) has been prepared at a small temperature (90°c) by citrate-gel auto combustion method. nd doped ni-co nano ferrite with the chemical formula ni0.4co0.6ndxfe2-xo4 (where 0.00 ≤ x ≤ 0.08) were synthesized by sol gel technique by using the following starting materials (cannas, falqui, musinu, peddis, & piccaluga, 2006). nickel nitrate, cobalt acetate, neodymium trinitrate hexahydrate, ferric nitrate, citric acid and ammonia and their detailed description of these starting materials required for the synthesis of neodymium doped nickel cobalt nano-ferrites by sol-gel auto-combustion method. proper quantities of nitrates of metals designated in the starting materials for nd doped ni-co nanocrystal system neodymium trinitrate, ferric nitrate and nickel nitrate along with other salts cobalt acetate and citric acid have been solved in isolated beakers. the mixture of nitrate was added with the properly calculated quantity of citric acid for the purpose of chelating agent. magnetic stirrer was used for mixing to get the homogenous solution. firstly, the solution temperature raised to 90 oc then ammonia solution was added at very slow rate to the citrate nitrate mixture for adjusting the ph in range 7 to 8 for each sample marked number 1 to 5. the mixture solution was maintained about 90 oc by continuous stirring with the help of hot magnetic plate for evaporation until a highly sticky gel obtained. finally, the viscous gel began bubbling and just after it gel started its combustion automatically. the ashes collected from beakers of each sample were grinded and collected it in the powdered form. finally, the dried and grinded sample of each composition of ni0.4co0.6ndxfe2-xo4 ferrite was annealed by using the controlled muffle furnace vulcan a550 as shown in figure. the annealing was done for 6 hours continuously and the temperature of the annealing was kept at 950ºc to obtain the proper spinel phase. after this all samples were ed into fine powder. several methods were used to find the different characteristics of the prepared samples with different compositions for analysis and investigation which are: xrd, ftir, vsm. 3. results and discussion 3.1. structural analysis the nanocrystals of ni0.4co0.6ndxfe2-xo4 spinel ferrites with 0.00 ≤ x ≤ 0.08 were synthesized by sol gel technique. the structural elucidation and magnetic behavior of nd doped ni-co ferrite studied with changed concentrations of neodymium in ni-co spinel ferrite. with the help of these observations, the substitution and distribution of nd3+ in a and b sublattices of nickel-cobalt ferrites was studied. the xrd peaks of neodymium doped nickel-cobalt nanocrystals with step size x = 0.00, 0.02, 0.04, 0.06 and 0.08 are shown in figure1 for all the prepared samples. table 1 x-ray density, secondary phase, porosity, lattice parameter and grain size of ni0.4co0.6ndxfe2-xo4 for 0.00 ≤ x ≤ 0.08 sample compositions secondary phase lattice constant a (å) x-ray density (g/cm3) grain size (nm) porosity ni0.4co0.6fe2o4 --8.373033 5.309609 25.90719 0.328702 ni0.4co0.6nd0.02fe1.98o4 --8.366359 5.362448 23.23839 0.426503 ni0.4co0.6nd0.04fe1.96o4 ndfeo3 8.35285 5.428825 22.98876 0.60207 ni0.4co0.6nd0.06fe1.94o4 ndfeo3 8.366754 5.441921 23.90425 0.426871 ni0.4co0.6nd0.08fe1.92o4 ndfeo3 8.355141 5.504928 23.97696 0.480963 the comparison of these peaks patterns for each sample with the reference data from the icdd nos. cofe2o4 (00-01-1121) and nife2o4 (00-03-0875) revealed the crystalline phases. the observed patterns showed a cubic spinel structure of single phase with another peak for secondary phase at x ≥ 0.04. the observed bragg’s reflections were indexed as (220), (311), (222), (400), (422), (511) and (440) with 2θ ranging from 25 to muhammad waqar, a. i. aljameel 36 80 degrees. x-ray density, secondary phase, grain size and lattice parameter (a) are recorded for ni0.4co0.6ndxfe2-xo4 ferrites system along with the compositions in following table1. figure 1: xrd patterns of ni0.4co0.6ndxfe2-xo4 spinel ferrites with 0.00 ≤ x ≤ 0.08 a peak corresponding to 2θ = 32.6 ̊ (indicated by * in fig.1) is denoted as secondary phase for x ≥ 0.04 at grain boundaries and with increasing concentration of nd, the intensity of the peak was also increased. the labelled peak recognized as ndfeo3 (iron neodymium oxide) corresponding with icdd no. 74-2203. this appearance of secondary phase is the consequence of larger reactiveness of fe3+ with the neodymium nd3+. it also confirms that nd3+ ion replacement has the solubility bound in lattice of nd doped nickel cobalt ferrites. the lattice parameter and distance between adjacent miller planes (h, k, l) were determined according to bragg’s equation for cubic lattice as: ( ) 1 2 2 2 2 2 sin h k l a   + + = (1) where a is lattice parameter, (h k l) are the interplanar distance, the x-ray wavelength is λ (anupama & rudraswamy, 2016). the average particle size estimated from the maximum intensity recorded (311) peaks of x-ray diffraction patterns with the formula given by scherrer’s as: 0.9 cos d    = (2) where average crystalline size is d of nanocrystal in nano meter, the x-ray wavelength taken 1.54 å is denoted by λ, the bragg’s angle is θ and the full width at half maximum (fwhm) is denoted by  . the table1 showed the values of crystallite size and lattice parameter. the calculated values for x-ray density of each sample are tabulated in table1. these values were calculated using the mathematical formula: 8 x a m n v  =  (3) where molecular weight is denoted by m of the sample, na denotes the avogadro’s number and volume of the cubical unit cell is v. journal of materials and physical sciences 2(1), 2021 37 figure 2: nd contents vs lattice parameter the trivial variations are there in lattice parameter ‘a’ that could be linked in the increasing nd3+ concentration, the ionic radii of nd3+ (0.983 å) is larger as compared to fe3+ (0.645 å). the lattice constant first somewhat reduced with neodymium count in the lattice and then increased with higher substitutions and then decreased again, as shown in the figure 2 and table1. it is clearly recognized that the lattice constant is powerfully reliant on the nd3+ ion radii. the substitution of a specific amount of nd3+ ions at the octahedral sites would rise the value of a compared to the undoped nicofe2o4 ferrite. the decrease in a by increase in nd3+ amount could be attributed to the ionic rearrangement between the existing interstitial octahedral b and tetrahedral a sites for the spinel frame. another reasonable description for the experimental reduction in lattice parameter can be made from likely vacancies of iron in the in crystallization process in samples because of the adding of a greater ion size in the b site. in addition that, by increasing of nd3+ concentration, the reduction in lattice parameter could be ascribed to the firmness of spinel lattice made by the secondary phases due to the difference in thermal expansion coefficients (dasan, guan, zahari, & chuan, 2017). figure 3: crystallite size as a function of nd concentration another experimental effect of neodymium exchange is the drop in the samples’ crystallite size. with the addition of nd amounts, the grain size was showing the reducing trend. the bond energy of nd3+–o2is higher than that of fe3+–o2may suggests that additional energy is desired to push the nd3+ to arrive the lattices and nd3+–o2form muhammad waqar, a. i. aljameel 38 bonding. consequently, higher thermal stability of the nd3+ substituted ferrites was observed as compared to the pure nickel cobalt ferrites, and higher amount of energy is required for the replaced samples to comprehensive grain crystallization and development (munir, ahmed, saqib, & anis-ur-rehman, 2016). also, it has been reported in literature that the hindrance in the development grains of the ferrite is the presence of formed ndfeo3 phase located near the grain boundary. it may also be suggested that the introduction of the nd3+ ions cause lattice stresses and a chaotic lattice structure. these variations confine grain crystallization and delay the grain evolution, consequently reducing the crystallite dimensions (peng et al., 2011). 3.2. spectroscopic analysis fourier transform infrared analysis deliver the data about the chemical changes and possession of the cations on different sites. figure 4 shows the fourier transform infrared analysis of ni0.4co0.6ndxfe2-xo4 ferrites for 0.00 ≤ x ≤ 0.08. in different compositions of prepared ferrites, in the range from 400 to 600 cm-1 two characteristics peaks were observed (junaid et al., 2016). ftir spectral analysis reveal the existence of characteristics bands that are ascribed to prepared nickel cobalt spinel ferrites. commonly, the band with higher frequency located in 500 to 600 cm-1 range characterizes the fundamental vibration of tetrahedral group, whereas the lesser frequency band in the range of 400–500 cm-1 represents the octahedral groups. these bands are characteristic feature of spinel ferrites (dasan et al., 2017). figure 4: ftir spectra of ni0.4co0.6ndxfe2-xo4 with 0.00 ≤ x ≤ 0.08 from the figure 4, it has observed that with the decrease in concentration of neodymium, the shifting of bands toward the lower wave number was noted. the bond length of octahedral site is greater than as compared to bond length of tetrahedral site causing the vibration of characteristics group seemed at smaller frequency in octahedral site than the tetrahedral site (dasan et al., 2017). absorption at frequency around ʋ2 (400-500 cm-1) is produced by elongating of the octa-hedral oxygen and metallic bond, while the absorption at frequency around ʋ1 (500600 cm-1) is caused by oxygen in the direction perpendicular to the axis joining the tetrahedral ion and oxygen (shobana, kwon, & choe, 2012). likewise, very intense peaks in range of 2900 cm-1 region can be attributed to c-h stretching frequencies. these were originated from the defect sites that exist within the structure of nd doped ni-co ferrites. supplementary, the bands displays absorption bands at 1396 cm-1 conforming to the presence of carboxyl group (coo-). the band for carbon oxygen stretching is also present at 1244 cm-1. there are also the bands with frequencies 1062 cm−1 and 890 cm-1 which show the presence of fe-co alloy system. the frequency band which present at 3672 cmjournal of materials and physical sciences 2(1), 2021 39 1 associated to oxygen-hydrogen vibration due to presence of absorbed water or moisture at surface. these observed peaks are tabulated in table 2 (rana, philip, & raj, 2010). figure 5: ftir spectra of ni0.4co0.6ndxfe2-xo4 with 0.00 ≤ x ≤ 0.08 table 2 ftir spectral bands of annealed ni0.4co0.6ndxfe2-xo4 ferrites nanoparticles from figure 4 and 5 samples’ composition frequency (cm-1) representations of appeared bands ni0.4co0.6ndxfe2-xo4 ferrites (0.00 ≤ x ≤ 0.08) annealed at 950oc for 6 hours 3672 (h–o) of free or absorbed water 2980, 2900 (c-h) stretching frequencies 1396 (coo-) carboxyl group 1244 (c-o) stretching frequency 1062, 890 iron–cobalt alloys 540.42 to 533.68 spinel characteristic (fe-o) (tetrahedral) 410.85 to 416.54 spinel characteristic (fe-o) (octahedral) it has been revealed from the fourier transform infrared analysis that the intensity of ʋ2 rises with neodymium increasing concentration. the cause of this intensity variation is neodymium ion preference to go at b site and pushes the fe ion to a site by increasing concentration of nd and rises the radius of b-site (dasan et al., 2017). the following formulae were used to found the force constants ko and kt: ko = 0.942128m ʋ22/(m+32) (4) kt = (2) 1/2 ko ʋ1/ ʋ2 (5) here ko is octahedral site force constant and kt is tetrahedral site force constants. m represents molecular weight, ʋ1 for frequency at tetrahedral and ʋ2 frequency at octahedral site. from table 3 it was observed that both ko and kt keep on increasing with increasing nd3+ concentration. rtetra = a (3) ½ (u 0.25 ro) (6) rocta = a (5/8 u) ro (7) where a represents lattice constant, u is oxygen positional parameter, ro represents oxygen radius, tetrahedral radii is rtetra and octahedral radii (1.32å) is rocta. for fcc crystal, the value of oxygen parameter is 0.375å. table 3 shows, it has been observed that the tetrahedral and octahedral radii decreased with the addition of nd3+ contents and the bond length decreases with the rise of nd concentration (junaid et al., 2016). muhammad waqar, a. i. aljameel 40 table 3 molecular weight, characteristics frequencies, ko, kt, sample composition and radii at octahedral and tetrahedra sites for ni0.4co0.6ndxfe2-xo4 ferrites (0.00 ≤ x ≤ 0.08) composition weight (gm/ mole) ʋ1 (cm-1) ʋ2 (cm-1) ko(dyne/ cm2)×105 kt(dyne/ cm2)×105 ro rt ni0.4co0.6fe2o4 234.523 533.68 410.85 1.399353 1.817711 0.7733 0.24994 ni0.4co0.6nd0.02fe1.98o4 236.291 535.43 413.73 1.420316 1.838107 0.7716 0.24869 ni0.4co0.6nd0.04fe1.96o4 238.059 537.89 416.19 1.438531 1.859178 0.7682 0.24616 ni0.4co0.6nd0.06fe1.94o4 239.827 539.59 416.47 1.441726 1.86794 0.7717 0.24877 ni0.4co0.6nd0.08fe1.92o4 241.595 540.42 416.54 1.443455 1.872741 0.7688 0.24659 3.3. magnetic properties the magnetic hysteresis loops are shown in the figure 6 for the ni0.4co0.6ndxfe2-xo4 with step size x = 0.00, 0.02, 0.04, 0.06 and 0.08. the small part from (h = -840 oe to 0 oe) and (m = 0 emu/g to 32 emu/g) is also there in set in the magnetic hysteresis loops figure 6 to show change in values of m vs h with change in concentration of doped neodymium. the small area of the hysteresis loops showed the magnetic behavior of the prepared ferrites as soft magnet. the energy dissipated during the setback of applied magnetic field responsible for the hysteresis loop area. many aspects like porosity, density, grain size and chemical composition are also influencing the outline and size of the loops, that also affected by the sintering process, heat treatment conditions and preparation method etc. (kadam, shinde, yadav, patil, & rajpure, 2013). figure 6: mh loops of ni0.4co0.6ndxfe2-xo4 with 0.00 ≤ x ≤ 0.08 the measurements for parameters like hc, ms and (mr) were calculated from loops in hysteresis mh curves and presented in the figure 7. it has been revealed from the figure 7 that the (ms) values for undoped nickel cobalt ferrite base sample is greater with comparison of the nd3+ ion replaced models because of high crystallinity (dasan et al., 2017). journal of materials and physical sciences 2(1), 2021 41 figure 7: saturation magnetization (ms) vs nd concentration of ni0.4co0.6ndxfe2-xo4 with 0.00 ≤ x ≤ 0.08 3.3.1.saturation magnetization (ms) it is clear from the figure 7 that ms is decreasing with the increase in nd3+ concentration. the reduction in ms can be associated to the strong irreversible movement and movement of the domain wall in the applied magnetic field direction. the domain wall energy that hindering the displacement for occurring should be higher than the external applied field. therefore, the tougher the displacement to occur will results in the reduction of the ms. further-more, magnetization may be defined as m = |mb–ma|, m decreases by the replacements at b-site (peng et al., 2011). the replacing nd3+ ions rather employed the bsite owing to their large ionic radii. the magnetic moment of fe3+ ions has larger value as of nd3+ ions (przeniosło et al., 1996). this work results also show accordance with it as magnetic moment shows a decreasing trend with increasing nd concentrations as prescribed in table 3. the decrease in the number of fe3+ ions at b-site cause the decrease in magnetization at b-sublattice, showing the observed decrease in ms with the ndsubstitution. the localized 4f electrons are the prime responsible factor for origin of the magnetic moments of rare earth metals which are considered by lower magnetic ordering temperatures. thus, they exhibits disordered orientatins of their magnetic dipole moment at room temperature and later at room temperature they show paramagnetic behavior and contribute very slight to the magnetization of doped ferrite. with increase in neodymium contents, magnetization decreases at b-sub lattice. moreover, nd3+ ions addition by substitution of fe3+ magnetic ions at b-site weakens a–b super exchange interactions. therefore the ferrimagnetic ordering of nickel cobalt ferrite has been distressed due the substitution of nd3+ ions and hence ms decreases (jacob, thankachan, xavier, & mohammed, 2013). 3.3.2.coercivity (hc) the overall trend of coercivity is increasing except for nd concentration at x = 0.04 as compared with the hc value of base sample having zero nd concentration. it is observed that hc first increase and then decrease from x = 0.02 to x = 0.04 and then increases for further doping from x = 0.04 to 0.08. this one step decrease in coercivity at x = 0.04 may be due to one of the any reason as hc is depends upon microstructural property, further having dependence on presence of nonmagnetic atoms, strain and defects etc. present in the material, porosity and anisotropy in magneto crystalline. also, this increasing trend of hc except x = 0.04 is in reciprocal relation with decreasing saturation magnetization values by increasing the concentration of doped rare earth metal neodymium. the effect of induced strain is the increase due to additional doping to the deformation of the spinel muhammad waqar, a. i. aljameel 42 lattice and the surplus presence of nd3+ ions in the lattice causes an increase in magneto crystalline anisotropy (singhal, barthwal, & chandra, 2006). table 4 saturation magnetization, retentivity, coercivity, remanence ratio and magnetic moment of ni0.4co0.6ndxfe2-xo4 (0.00 ≤ x ≤ 0.08) composition ms (emu/gm) mr (emu/gm) remanence r = mr / ms hc (oe) magnetic moment µb ni0.4co0.6fe2o4 68.16 31.85 0.467282864 790 2.86215 ni0.4co0.6nd0.02fe1.98o4 65.26 30 0.459699663 809 2.761032 ni0.4co0.6nd0.04fe1.96o4 62.38 28 0.448861815 765 2.658931 ni0.4co0.6nd0.06fe1.94o4 60.28 28.5 0.47279363 797 2.588501 ni0.4co0.6nd0.08fe1.92o4 58.19 27.8 0.477745317 818 2.517174 another way to explain the coercivity is the grain size. there is inverse relation between coercivity and grain size. a higher number of domain walls are there for the larger grains. the less amount of energy needed for the magnetization or demagnetization by domain wall movement as compared to that of due to domain rotation. opposite to this, with the increase in grain size, movement of walls increases with the higher number of grain walls and this influences magnetization or demagnetization caused by domain rotation (costa, tortella, morelli, & kiminami, 2003). consequently, lower coercivity values are expected for the samples having larger grains and vice versa. this may be important reason in coercivity values for the synthesized nickel cobalt ferrites with doping of nd3+ ions for 0.00 ≤ x ≤ 0.08. also, the presence of impurities which are distributed in the grain boundary are a pause and go counter to the domain walls displacement. because of the presence of the secondary phase ndfeo3 and the corresponding, the higher coercivity values are expected for samples with more nd3+ ions as shown in table 4 (peng et al., 2011). 3.3.3.remanence ratio (r) the “remanence ratio r = mr / ms is a sign of the comfort by which the direction of magnetization reoriented to most nearly easy axis magnetization direction after the removal magnetic field”. the isotropic nature of the synthesized samples is being revealed from the lower value of r (shirsath, toksha, & jadhav, 2009). from table 4, it can be observed that the variation in r with changing compositions is comparable to hc. therefore doping of nd3+ in nickel-cobalt nanoferrite lead to the decrease in magnetic hysteresis loss for the nanocrystals. also the sample ni0.4co0.6nd0.04fe1.96o4 showed the minimum loss. the decrease in magneto crystalline anisotropy and grain growth because of doping of neodymium could be the major reason for the hysteresis loss reduction for doped ferrites from x = 0.02 to x = 0.04. the value of saturation magnetization is lower in comparison with undoped base sample of nickel-cobalt ferrites. it may be clarified by means of the core–shell model, which states that the effects due to finite size of the nanocrystals may lead to a canting of spins on the surface and thus decreases the magnetization (jacob et al., 2013). conclusion sol-gel auto combustion method was used to synthesize the nickel cobalt nanoferrites with neodymium doping to study the structural, spectral and magnetic properties. the observed results are being discussed in this conclusion. the x-ray diffraction patterns of the prepared samples confirmed the spinel phases. an extra peak was observed for the samples with concentration of neodymium x ≥ 0.04 that shows the formation of ndfeo3. some trivial changes are observed in lattice constant and the crystallite size. lattice constant found first to decrease up to x = 0.04 then increase for x = 0.06 and again decrease for x = 0.08. the reduction in the crystallite size as compared to base sample was observed by adding neodymium in nickel cobalt nanoferrites with slight increase after x > 0.04. the cubic spinel characteristics frequency bands were also there in ftir spectra with shifting towards lower wave number with decrease in neodymium concentrations. other peaks were also observed in ftir spectra showing the presence of different stretching frequency vibrations for the samples. tetrahedral and octahedral radius were calculated. force constants showed the decreasing behavior with the increase in journal of materials and physical sciences 2(1), 2021 43 neodymium concentration. a decreasing trend was observed for the saturation magnetization with increase in neodymium doping as compared to undoped nickel cobalt ferrites. the coercivity value was also found in increasing order as compared to base sample except x = 0.04. the variation in remanence ratio was similar to that of 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(2006). xrd, magnetic and mössbauer spectral studies of nano size aluminum substituted cobalt ferrites (coalxfe 2− xo 4). journal of magnetism and magnetic materials, 306(2), 233-240. https://doi.org/10.52131/jmps.2021.0201.0011 1 journal of materials and physical sciences volume 2, number 1, 2021, pages 01 11 journal homepage: https://journals.internationalrasd.org/index.php/jmps enhancement in corrosion resistance and hardness of az91d magnesium alloy by carbon ion implantation m. kashif mumtaz1, g. murtaza1* 1 centre for advanced studies in physics, gc university, lahore-54000 article info abstract article history: received: february 02, 2021 revised: april 06, 2021 accepted: june 28, 2021 available online: june 30, 2021 to improve the mechanical and corrosion resistance of az91d magnesium alloy, carbon ion implantation technique has been carried out using 2 mv pelletron accelerator on the polished magnesium alloy surface. vickers hardness test, particle induced x-ray emission (pixe) analysis, scanning electron microscopy (sem), x-ray diffraction (xrd) and corrosion tests are employed to analyse the properties. vickers hardness tests revealed the improvement in surface hardness which we infer is due to the enhancement in dislocation density, as a consequence of carbon ion implantation with varied dose from 1.26×1013 to 8.4×1014 ions-cm-2. that is, the increase in hardness is directly related to the ion dose, variation in lattice parameters, crystallite size, and change in peak intensity, all due to the increase in ion fluence. the non-destructive elemental analysis, pixe, gave the elemental profile before and after ion implantation. sem results indicated that singly ionized carbon ion implantation has modified the surface of az91d mg-alloy. xrd results showed that the unexposed and treated samples include α-mg and β-mg17al12 phases. xrd results also revealed that after the carbon ion implantation the diffraction peak position and intensity of all the phases shifted. the corrosion tests were carried out using two methods, namely, weight loss method and electrochemical test. the results guided that for a higher dose of ion implantation, the corrosion resistance increased and loss of mass of exposed surface of specimens decreased, which reflect the enhancement of corrosion resistance. keywords: mg-alloy ion implantation x-ray diffraction corrosion test scanning electron microscopy hardness © 2021 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: gmrai@gcu.edu.pk 1. introduction magnesium has a vast area of applications in pure and alloy form in; automotive, biomedical, electronics and aerospace industry. despite lighter in weight, it has high specific strength and dimensional stability, and recycling potential (höche, blawert, cavellier, busardo, & gloriant, 2011; ueda, reuther, & lepienski, 2005; wang, li, xiong, tian, & yang, 2011). magnesium is the lightest by weight among all commonly used materials with a density of 1.74 g-cm-3 which is approximately one-third of that of aluminium. it oxidizes/corrodes in normal humid air, and the oxide layer thus developed does not shield the rest from humidity and further corrosion carries on. this deprived corrosion resistance limits its use in many industrial applications (h. liu, xu, jiang, wang, & zhang, 2013; song, johannesson, hapugoda, & stjohn, 2004; tian, wei, yang, fu, & chu, 2005). the main reason is its low potential (e0 = -2.34 v vs. normal hydrogen electrode) even against the normal atmospheric conditions. https://journals.internationalrasd.org/index.php/jmps mailto:gmrai@gcu.edu.pk m. kashif mumtaz, g. murtaza 2 the corrosion is defined as the eating away of metals and alloys due to physical, chemical and electrochemical reactions with its environment. it depends upon the movement of the electrons, ions and atoms (r. xu et al., 2012). increase in corrosion resistance may cause a decrease in corrosion rate which will not only enhance the mechanical properties but also a life of parts in automation, communication and consumer electronics, aerospace engineering, electromagnetic shielding and good dimensional stability. generally, corrosion is classified into two types. (a) aqueous or wet corrosion. (b) dry corrosion due to interaction between metal and any oxidizing gas like oxygen, carbon dioxide or oxidizing sulphur at elevated temperatures (suresh, srinivasan, pillai, & pai, 2013). wet corrosion is produced in the prances of liquid (water) or an aqueous solution of electrolytes. dry corrosion is produced in the absence of a liquid phase. in this kind of corrosion, vapours and gases are the co rodents at high temperatures (y. li et al., 2014). several workers have explored different techniques for the surface modifications of mg alloys; physical vapour deposition, nitrogen ion implantation, chemical conversion coatings, micro-arc oxidation, electroless nickel deposition, ion implantation, super-hydrophobic coating, chemical conversion coating and slippery coatings (butt et al., 2019; gu, yan, zhang, & tu, 2016; y. li et al., 2014; suresh et al., 2013; tian et al., 2005; r. xu et al., 2012; j. zhang, gu, tong, yan, & tu, 2016; j. zhang, gu, & tu, 2017). ion implantation is a material modification process in which ions are accelerated and bombarded on the surface of the sample. in this material-engineering process, the mechanical, electrical, chemical and physical properties of materials are modified. mostly, it is used for the fabrication of semiconductor devices, and for metal finishing and various applications of material science projects (tian et al., 2005). if the implanted ions have a mass comparable to the atoms of the target surface, then atoms of the sample are knocked out resulting in local surface modification. ion implantation, especially, carbon ion implantation, has given significant results to enhance the corrosion resistance (höche et al., 2011; h. liu et al., 2013; ueda et al., 2005; wang et al., 2011) and/or mechanical properties (butt et al., 2019; y. li et al., 2014; h. liu et al., 2013; song et al., 2004; suresh et al., 2013; tian et al., 2005; r. xu et al., 2012). for biomedical applications, the corrosion resistance of magnesium alloys must be improved while maintaining the surface morphology and biocompatibility. for this purpose, carbon has beneficial, clinical, chemical, and physical characteristics (höche et al., 2011; h. liu et al., 2013; ueda et al., 2005; wang et al., 2011). therefore, carbon ion implantation technique may help to enhance the corrosion resistance and biocompatible characteristics of mg-alloy. carbon ion implantation may increase the electrochemical behaviour of mg-alloy, demonstrating remarkable improvement in corrosion resistance. previously, carbon ion implantations gave reasonably good results on steel, aluminium, titanium and zirconium alloys. having knowledge of the known possibilities, based on prior work by several authors (butt et al., 2019). in this study, carbon ion implantation on az91d magnesium alloy is studied and the consequent improvement in corrosion resistance and the changes of mechanical properties have been calculated. 2. experimental details 2.1. sample preparations total eight number of az91d mg alloy samples, with a thickness of 0.5 cm (each) were prepared. whereas, four were cut into a square [2×2 cm2] and the other four were rectangular strips [4×2 cm2]. after cutting, the samples were ground up employing abrasive sic papers, sequentially with 320, 500, 1000, 1500, 2000 and 3000 grits, followed by final polishing using 10 µm diamond paste. after each stage of grinding and final polishing, the samples were carefully washed using an ultrasonic bath and rinsed with acetone. note that out of eight samples, one pair (one squared and one rectangular shaped) were kept without ion implantation (we name these as untreated) and other three pair were dosed with similar three ion implantations and are named as sample1, sample2 and sample3 respectively. one set of four samples (squared ones) were used for xrd, sem and pixe analyses, whereas the other set was used for micro hardness and electrochemical tests. journal of materials and physical sciences 2(1), 2021 3 2.2. ion implantation and characterizations three pair of az91d mg-alloy were selected for ion implantation. singly charged carbon ions were used for implantation in evacuated target chamber of 2 mv pelletron accelerator, installed at casp, gc university lahore. these ions were produced by sputtering from cesium target. a maximum of 500 kev energy was given to the carbon ions, which is enough to make the ions stay near the surface of the sample (höche et al., 2011). energy remained the same for all three pair but dose (ions-cm-2) was different which is: 1.26 × 1013, 5.0 × 1013 and 8.4 × 1014. pixe analysis of the untreated and carbon-beam treated samples were carried out, setting the beam of protons to an energy of 4 mev and maintaining a current of 20 na as optimized set of parameters (shafique et al., 2016), giving good combination of background ratios and high cross-section for the element of interest (az91d in our case). the diameter of the beam was adjusted to 400 µm and samples were placed perpendicularly facing the beam. a si-li detector was placed at an orientation of 45o to the beam direction and 10 cm apart from the sample. the consequent characteristic x-ray spectra were collected at the detector of a multi-channel analyser and were concluded using gupix software. 2.3. corrosion tests 2.3.1.weight loss method weight loss method is the most commonly used technique of all corrosion rate measurements (yan et al., 2015). the samples were measured for weight and then exposed to a corrodent for a known period followed by re-weight. the rate of loss in mass due to corrosion can be calculated by using 𝑅 = 𝐾𝑊/𝜌𝐴𝑇 (1) 𝑊 = 𝑅𝜌𝐴𝑇/𝐾 (2) where w is weight loss (gm), r is corrosion rate (mmpy), ρ is density (g cm-3), a is the area (cm2), t is a time of exposure (hours or days) and k is constant. weight loss is measured in mg dm-3 (days). it is time dependent technique in which time duration of (2, 10, 15, 20 and 30 days) was used. the corrosion rate is expressed in mills penetration per year (mpy). the corrosion rate in (mpy) can be calculated by using, mpy = 534w/dat. where w = weight loss in mg, a = area in sq. cm, t = time of exposure in hours, d is the density of the metal in g cm-3 (khosro aghayani & niroumand, 2011; p. li, han, xin, zhu, & lei, 2008). 2.3.2.electrochemical test the corrosion rate of the metals/alloys can be calculated in a more rigorous way of using the electrochemical test, based on faraday’s first law, as described in theory, the current is uniformly distributed over the wetted surface area (baboian, 2005). 𝐶𝑅(𝑚𝑚𝑝𝑦) = 𝐾1𝑖𝑐𝑜𝑟𝑟(𝐸.𝑊.) 𝜌 (3) where cr is the corrosion rate (mmpy), k1 is constant (3.27×10-3 mm µa-1 cm-1 y1), icorr is the corrosion current density (µa cm2), e.w. is the equivalent weight (g) and ρ is the density (g cm-3). using the equivalent weight (e.w. = 12.16 g) and density (ρ = 1.74 g cm-3) (langford & wilson, 1978), equation 3 can be reduced to 𝐶𝑅(𝑚𝑝𝑦) = 0.90 𝑖𝑐𝑜𝑟𝑟 (4) where icorr is determined for each experiment using tafel plots. briefly, a graph is plotted between; electrode potential vs. sce (saturated calomel electrode) (along y-axis) and logi (along x-axis). the slopes of tangents to anodic (βa) and cathodic (βc) branches are interpolated and their intersection point determines the value of icorr and ecorr in the plane of a graph (for more detail, see (baboian, 2005)). m. kashif mumtaz, g. murtaza 4 3. results and discussion 3.1. xrd analysis xrd analysis of mg-alloy provides information about phases of crystalline structure. figure 1 shows a variation in the structure before and after carbon implantation. three main peaks of the untreated alloy have appeared at 32.453º, 34.647º, 36.336º, which are attributed to αmg phase as mg (100), mg(002) and mg(101) planes. however, after ion implantation clear variations are observed in these main peaks as well as another phase has been observed. the pure and secondary phase .e., αmg and β-mg17al12 are matched very well with the (jcpds nos. 04-0770 and 01-1128), respectively. using scherrer equation (langford & wilson, 1978) and unit cell software (tim holland and simon redfern), crystallites size and lattice parameters of the untreated and treated samples are calculated and given in table 1: 𝐷 = 𝑘𝜆 𝜋 180 √𝜔𝑖 2−𝜔0 2 𝑐𝑜𝑠𝜃 (5) where, 𝜅 has value 1 and a dimensionless constant that is related to the shape and distribution of crystallites (klug & alexander, 1954) 𝜆 is the wavelength of x-ray and 𝜃 is the bragg angle. 𝜔0 and 𝜔𝑖 are the full width at half maximum (fwhm). these results clearly exhibit the effect of carbon ions in the composites of mg alloys, as the lattice parameters initially decrease and then a slight increment has been observed at the last dose. 20 30 40 50 60 70 80 * in te n s it y ( a .u .) 2 (degree) 1 0 0 unexposed 1.2 x 10 13 5 x 10 13 8.4 x 10 14 0 0 2 1 0 1 1 0 2 1 1 0 1 0 3 0 0 4 0 0 4 * * −mg 17 al 12 the indexed peaks are -mg sample 1 sample 2 sample 3 figure 1: xrd spectrum of unexposed and exposed az91d mg alloys with variable dose of carbon ion implantation table 1 lattice parameters, cell volume and crystallites size calculated from xrd data samples a (å) c (å) v (å)3 d(å) unexposed 3.205 5.186 46.148 276.6 sample 1 3.194 5.160 45.611 210.1 sample 2 3.209 5.185 46.244 136.25 sample 3 3.195 5.269 46.586 175.75 journal of materials and physical sciences 2(1), 2021 5 similarly, crystallite size decreases with the ion implantation, which is also good evidence for the incorporation of carbon ions and a good agreement with the literature (abdi & savaloni, 2016). it is revealed that after carbon ion implantation crystallinity decreases with respect to ion dose. the intensity of all the peaks appears suppressed as compared with that of the untreated sample. moreover, the β-mg17al12 phase seems to be more prominent for a higher dose of carbon ions, variation in the intensity due to ion implantation has been described by makinson et al, (makinson et al., 2000). xrd data reveals that the variation in the intensity, lattice parameters and crystallites play a vital role in the corrosion, which has been discussed in the previous section (b. s. liu, wei, chen, hou, & guo, 2015). 3.2. pixe analysis the elemental compositions of; the seawater treated and untreated samples (using pixe) are shown in figs. 2(a-b), where the number of counts is plotted against the energy of the emitted characteristic x-rays. fig. 2(a) depicts the elemental analysis and confirms the existence of mg, si, mn, al and zn in az91d mg alloy. it also reveals that after the carbon ion implantation, the peak of si is suppressed due to the incorporation of c ions. since carbon and silicon belong to the same group, there is more tendency that the carbon ions may replace the si position. due to pixe limitations of lower atomic number, c ions are not shown in spectra. whence the variation in peaks predicts the existence of c ions due to the fluence of the ion dose. 0 5 10 15 20 energy (kev) unexposed c o u n ts ( a .u .) al mg si s mn zn zn fluence 1.2×10 13 cm -2 sample 1 fluence 5×10 13 cm -2 sample 2 fluence 8.4×10 14 cm -2 (a) sample 3 0 5 10 15 20 unexposed znni energy (kev) imerse in salt al al si cl mn zn fluence 1.2×10 13 cm -2 +imerse in salt mg cr ni sample 1 fluence 5×10 13 cm -2 +imerse in salt sample 2 fluence 8.4×10 14 cm -2 +imerse in salt (b) sample 3 figure 2: pixe spectrum of az91d mg alloys; (a) before and (b) after immersion in nacl with different fluence of c ions similarly, fig 2(b) depicts the elemental analysis of the samples after treated with 3.5 % nacl solution for 30 days. results predict a few new elements after immersion in the solution, such as na, cl, ca, fe, cr and ni. existence of ni and cr might be associated with a thick layer of corrosive product, arose on the surface of samples. although, cr element is not part of the sample, however, it reacts with the alloy from solution side and becomes m. kashif mumtaz, g. murtaza 6 prominent at the surface of the samples, as shown in fig 2(b). also, the peak of ni is due to the reaction of the solution with the sample, as ni exists in small proportion in az91d. 3.3. sem analysis figure 3 presents the microstructure of az91d. the unexposed sample, fig. 3a (which is alloy matrix) contains large amount α-mg phase with scattered granular and flower-shaped particles inside the grain and along the grain boundaries. while the images of carbon implanted ions samples given in figs. 3(b-d), show micro-cracks on the surface of alloys which may be caused by desorption of water during heat treatment due to incorporation of carbon ions (j. xu et al., 2017). by increasing, the ion dose from 1.26×1013 to 8.4 ×1014 ions-cm-2, the consequent damage also increases, which led to the propagation of microcracks with elongated shape structure to release the accumulated stress (l.-n. zhang et al., 2013). these irradiation outcomes also guide us for the formation of barrier layers on the surface of specimens, causing the resistance to corrosion and will be discussed later (uglov, cherenda, danilyuk, & rauschenbach, 2000). one can see that with different ion dose, the surfaces of the exposed samples are changed altogether. the sem micrographs represent the grey and bright regions that lead to different zones on the surface of mg-alloy, which is in agreement with the previous study (suresh et al., 2013; r. xu et al., 2012). figure 3: sem surface images of unexposed sample and samples1, 2, and 3 which exhibit the surface modification due to the appearance of micro-cracks grains and tangled forest of dislocations 3.4. microhardness tests to assess the localized surface modification, the surface morphology of the samples was tested using a vickers hardness testing instrument. the test was conducted using 200 gm load with a set time of 10 s. each sample was indented on three neighbouring planar points, thereby calculating the average value of vickers hardness. the untreated sample stood with hv0 = 82.76. the sample dosed with minimal in the set (1.26×1013 ions-cm-2) showed increased hardness hv1 = 83.9, and next higher dosed sample (5×1013 ions-cm-2) journal of materials and physical sciences 2(1), 2021 7 did not give a remarkable further increase in the hardness hv2 = 84.0 and the highest dosed sample (8.4×1014 ions-cm-2) presented the highest value hv3 = 90.1. the resulting average hardness value was plotted against the corresponding dose as shown in figure 4. the graph shows that hardness has increased directly with dose. generally, the measurements and calculations demonstrated that the microhardness tends to increase by increasing dose. 0 2 4 6 8 10 82 84 86 88 90 92 sample 3 sample 2 5 x 10 14 cm -2 h a rd n e s s (h v ) fluence of carbon ions unexposed 1.26 x 10 13 cm -2 5 x 10 13 cm -2 sample 1 figure 4: hardness assessment by using vickers hardness test against implantation microhardness enhancement might be associated with the microstructural defects, the formation of dislocation clusters and re-adjustment of interstitial sites which depends on dislocation density. this, for obvious reasons, has occurred in these samples by c ions implantation. from the microstructural modifications (due to ion dose, as discussed above), the localized increase in hardness can be associated to new phase formations and the distribution of grain size in the matrix, thereby increasing the barrier force. inferring, these factors may be denounced for the increase in the microhardness which are consequences of ion implantation. 3.5. corrosion tests 3.5.1.weight loss test prepared and treated (carbon ion-implanted) samples of interest were exposed to a corrodent (seawater, 3.5% nacl solution in this study) for several days to determine the corrosion resistance with the help of loss in mass as given in table 2. the data are plotted in figure 5, which shows that there is a trend of reduced mass loss with an increase of ion dose (going from left (non-immersed) to right (more dosed samples)). after 2 days, the loss of mass is the least. given more immersion time the loss of mass is higher which is an anticipated result. the calculated rate of mass loss is plotted in figure 6. results confirm that after thirty days, corrosion resistance and loss in mass are found inversely related. the high dosed sample has maximum corrosion resistance and minimum loss in mass. the results and measurements describe that due to an increase in ion dose of implantation, corrosion resistance also increases the loss of mass of specimens decreases. which reflects the enhancement effect of corrosion resistance as shown in figs. 5-6. table 2 loss in mass of four samples exposed with given doses loss of mass (g) 2 days 10 days 15 days 20 days 30 days m. kashif mumtaz, g. murtaza 8 unexposed 0.21 0.54 0.39 0.46 0.66 sample 1 0.18 0.36 0.34 0.35 0.38 sample 2 0.12 0.22 0.27 0.26 0.29 sample 3 0.07 0.18 0.16 0.14 0.12 unexposed sample 1 sample 2 sample 3 0.1 0.2 0.3 0.4 0.5 0.6 0.7 l o s s i n m a s s ( g ) samples of different ion doses loss in mass after 2 days loss in mass after 10 days loss in mass after 15 days loss in mass after 20 days loss in mass after 30 days figure 5: corrosion resistance increases with increase of ion dose and loss in mass (w) decreases unexposed sample1 sample2 sample3 20 30 40 50 60 70 c o rr o s io n r a te [ m p y ] sample number figure 6: corrosion rate (mpy) as determined by weight loss method 3.5.2.electrochemical test journal of materials and physical sciences 2(1), 2021 9 the electrochemical test results are given in table 3. the data are plotted in fig. 7. the trend is obviously the same as of weight-loss method, i.e. the corrosion resistance has increased with ion dose as direct. the tabulated parameters (beta a, beta c, icorr and the cr), all have a similar trend of showing values decreasing with dose, but the ecorr does not show a similar trend. which may be associated with the change of mass (loss) due to immersion and the consequent change of shape (corroded) and density of the sample. 1e-6 1e-5 1e-4 1e-3 0.01 0.1 -2.0 -1.5 -1.0 -0.5 0.0 e ,v (s c e ) i, a cm -2 unexposed sample 1 sample 2 sample 3 figure 7: tafel plots for az91d immersed in 3.5 wt. % nacl solution table 3 the electrochemical test parameters and corrosion rate electrochemical parameters unexposed sample1 sample2 sample3 beta a (v/decade) 442.6 × 10-3 157.5 × 10-3 129.5 × 10-3 117.4 × 10-3 beta c (v/decade) 344.5 × 10-3 266.3× 10-3 233.7 × 10-3 188.9 × 10-3 icorr (µa cm2) 180 112 95.9 67.7 ecorr (volts) -1.37 -1.27 -1.32 -1.35 cr (mpy) 162.4 101 86.5 61.1 it has been observed that the absolute values of corrosion rate just determined should not be considered right away due to various factors not covered in this study. but more important is that the calculated values by using two methods show the same trend of increasing corrosion resistance with dose. 4. conclusions eight samples of az91d magnesium alloy were tested, where three pair were implanted with 500 kev energy and a different dose of ions from 1.26×1013,5 × 1013and 8.4×1014 ions-cm-2 by using 2 mv pelletron accelerator. the characterizations of the samples were done by using xrd, sem, vickers hardness, weight loss and electrochemical tests for corrosion rate determination. it was found that after carbon ions implantation, the existence of two phases’ α-phase and β-phase were confirmed by xrd analysis. surface modifications and carbon ions interacted structural changes were examined by sem. from experimental results, we conclude that hardness and corrosion resistance have been progressed. these two effective outcomes have been verified by using a hardness test and corrosion resistance test. carbon ion implantation on mg alloy creates productive, astonishing, and effective characteristics at the same time i.e. corrosion resistance and hardness. these two factors play an important and revolutionary role in a variety of applications in preferable, effectual point of view. the improved quality of mgalloy may play an impressive role in biocompatibility, aerospace and electromagnetic shielding for m. kashif mumtaz, g. murtaza 10 being lightweight and improved characteristics (r. xu et al., 2014). from the above results of corrosion testing, it can be concluded that carbon-ion implantation on az91d mg-alloy is a useful technique to give strength against corrodents. this ability enhances its commercial exploitation in many aspects (mao et al., 2015), which works in a way directly related to the 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tb-cr substitution on the structural and magnetic properties of cobalt ferrites abdul hameed1, muhammad waqas khaliq2* 1 institute of physics, the islamia university of bahawalpur, bahawalpur-63100, pakistan 2 alba synchrotron light source, carrer de la llum, 2, 26, 08290 cerdanyola del vallès, barcelona, spain article info abstract article history: received: july 18, 2021 revised: september 16, 2021 accepted: december 29, 2021 available online: december 31, 2021 the impact of tb-cr substitution in cobalt-based ferrites having composition co1-xtbxfe2-ycryo4 (x=0.0-0.1, y=0.0-0.5) prepared by solid state reaction method on structural, magnetic and dielectric parameters was explored. structural analysis was carried out by x-ray diffraction technique. a variation in lattice parameter (a) was observed as a function of doping. the lattice constant ‘a’ increases from 8.37 å to 8.39 å, whereas crystallite size (d) decreases from 44 nm to 28 nm with tb-cr substitution. unit cell volume was found in the range 586.8 å3 590.6 å3. x-ray density, bulk density as well as porosity were also affected with the inclusion of tb-cr ions. saturation magnetization and remanence were observed to decrease from 62 emu/g to 51 emu/g and 13.38 emu/g to 8.29 emu/g, respectively with the addition of tb-cr contents. the incorporation of tb-cr cations caused the decrease in dielectric parameters like dielectric constant as well as dielectric loss. keywords: spinel ferrites x-ray diffraction magnetization coercive force dielectric properties © 2021 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: mkhaliq@cells.es 1. introduction ferrites, magnetic materials, are relatively inexpensive and thermally stable than other magnetic materials. these materials have extensive industrial applications like highfrequency circuits, transformer cores, high-quality filters, and operating devices (shirsath, jadhav, toksha, patange, & jadhav, 2011). the field of spinel ferrite is an important class of ferrite family due to its potential applications in different fields such as electronics, modern technology, and electrical and microwave industries. multilayer chip indicators are unique, essential elements of modern electronics products used in videos cameras, notebook computers, cellular phones, and silver electrodes (bhandare, jamadar, pathan, chougule, & shaikh, 2011). the researchers and engineers have investigated that nanoferrites show tremendous properties compared to their bulk counterparts. in the nano regime, grain boundaries control physical properties instead of grains (gadkari, shinde, & vasambekar, 2013). recently, cobalt ferrites have been extensively focused on their use in electrical and microwave industries, such as reflection coils, antennas, inductors, transformers cores, and nano-metric scales as ultrafine powders (patange et al., 2011). though, the uses of ferrites depend on their soft magnetic and hard magnetic nature. ferrites exhibiting a high coercive field (hc) are an essential parameter as these materials having significant coercivity can be used in many advanced applications. cobalt ferrite is considered a hard magnetic material because of its large coercivity and reasonable saturation magnetization, a prerequisite for high-density magnetic recording and data storage devices. their high coercivity value results from the high anisotropy of the co2+ ions because of its significant spin-orbit coupling (mallapur et al., 2009). electrical and magnetic characteristics of ferrites https://journals.internationalrasd.org/index.php/jmps mailto:mkhaliq@cells.es abdul hameed, muhammad waqas khaliq 55 can be tailored by doping the transition metals (ni, co, zn, cd, etc.) as well as the rare earth elements (gd, dy, tb, etc.) synthesized via various techniques (ahmed, afify, el zawawia, & azab, 2012; batoo, kumar, lee, & alimuddin, 2009; zhao et al., 2006). the distribution of cations at octahedral (b) and tetrahedral (a) sites plays a chief role in controlling the structural, electric, dielectric, and magnetic behavior (g. kumar et al., 2013). the rare earth cations have unpaired 4f electrons with ionic radii larger than fe cation when substituted in spinel ferrite lattice, ensuring structural, magnetic, and electrical properties (asif iqbal et al., 2014). s. g kakade et al. synthesized the er3+ substituted cobalt ferrites and studied that structural, electrical, magnetic, and dielectric parameters were changed and exhibited significant changes with doping the rare earth metals. the optimized electric resistivity shows that the prepared samples are applicable for decreasing eddy current losses at large frequency regions and can be suitable for multilayer chip inductor (mlci) devices (kakade, kambale, kolekar, & ramana, 2016). h-z duan et al. investigated the influence of rare earth cation on absorbing and magnetic properties of ce doped ni-co hollow spheres nanoparticles synthesized via hydrothermal method (duan, zhou, cheng, chen, & li, 2017). in recent work, we explored the influence of tb-cr doping for fe-co in cobalt-based ferrites by the standard ceramic method. the cobalt-based ferrites have been explored for their outstanding uses in magnetic recording media and em attenuation. the central theme of this work is to elucidate the changes in structural parameters, absorption bands, and magnetic as well dielectric properties with doping of transition (cr) and rare-earth element (tb). the optimized results of this research are discussed here in detail. 2. experimental methods cobalt ferrite and tb-cr substituted cobalt ferrites were fabricated by the standard ceramic method. analytical reagents were used to prepare tb and cr doped cobalt spinel ferrites with composition co1-xtbxfe2-ycryo4 (x = 0.0-0.1, y=0.0-0.5) using starting materials fe2o3 (sigma-aldrich 99.9 %), coo (sigma-aldrich 99.9 %), tb4o7 (sigma-aldrich 99.9 %) and cr2o3 (sigma-aldrich 99.9 %). these materials were combined in a stoichiometric ratio to prepare the required compositions. the dried residues were then ground for 4 hours using a pestle and mortar to obtain the fine powders. the ground powders were then converted into pellets at a pressure of (~35 kn) for 5 minutes by a paul-otto weber hydraulic press. after that, the samples were firstly sintered at 650 °c for 24 hours and finally sintered at 825 °c for eight hours, followed by air quenching. differential thermal analysis and thermogravimetric analysis of un-sintered powder were carried out to investigate the sintering temperatures by the thermal analyzer instrument model; mettler toledo gc 200), having a heating rate of 10 ºc/min. x-ray diffraction statistics data were collected using bruker d8-advanced x-ray diffractometer with cu-kα radiation (λ=1.54178 å). magnetization measurements under an applied magnetic field of ±1t were carried out at room temperature using a quantum design vibrating sample magnetometer (vsm: model 6000). dielectric parameters were examined for a frequency range 1mhz to 3ghz using the two probe method. 3. results and discussion 3.1. tga/dta analysis figure 1 shows the thermogravimetric (tga), differential gravimetric (dta), and differential scanning calorimetric (dsc) studies for un-annealed co0.96tb0.04fe1.8cr0.2o4 ferrite sample. tga curve depicts that the entire weight loss of material was 19.4 % which was split into four portions. the first loss was 6.24 % at 82 °c, followed by a second loss of 3.16 % at 158.7 °c because of water evaporation. in the third part, 6.9 % weight loss was observed at 262 °c because of the decomposition of another phase before the development of spinel ferrite (mahmood et al., 2013). in the last part, weight loss was 2.1% from 262 to 950 °c because of the transition of metal oxides into ferrite materials. this temperature is the annealing temperature [14]. further, no additional weight loss after 950°c was seen, which proves the complete journal of materials and physical sciences 2(2), 2021 56 breakdown of complexes and shows the completion of phase formation.(farhadi & rashidi, 2010). figure 1: tga, dta, dsc curves for as-prepared co0.96tb0.04fe1.8cr0.2o4 sample dta analysis describes the decomposition rate of material. the amount of the reacting substances can be measured through the area of the peak. endothermic peaks describe phase transition, dehydration, and reduction, while exothermic peaks describe the crystallization and oxidation processes. the differential scanning calorimetry (dsc) curve of the sample is also shown in figure 1. in the dta curve, peaks appeared at 65.31 °c, and 215.5 °c designate the breakdown of anions, whereas a sharp peak at 356 °c depicts the breakdown of metallic complexes. the peak at 228.95 °c describes the exothermic behavior due to the heat evolved during the crystallization of ferrite material. 3.2. structural analysis figure 2 shows the xrd spectra of terbium and chromium co-doped cobalt ferrites with composition co01-xtbxfe2-ycryo4 (x=0-0.1, y=0.1-0.5).the xrd spectra of entire samples reveal the xrd peaks, which are indexed as (111), (220), (311), (222), (400), (422), (511), and (440) reflections (muhammad azhar khan et al., 2015; mukhtar et al., 2015). these xrd peaks are the characteristics planes of single-phase cubic spinel structure. the addition of tb and cr in the cobalt ferrite exhibits the presence of the tbfeo3 residual phase (*). this peak is observed at an angle of 33. 47° and is found as (322) plane of tbfeo3 orthorhombic phase confirmed through icdd # 88-0144. the tb-cr co-doped cobalt soft ferrites reveal the secondary phase peak, and its intensity gradually increases with the incorporation of dopants. it is also observed that the incorporation of larger radii rare earth cations increases the lattice constant due to the formation of the secondary phase (m. azhar khan et al., 2009). the crystallite size of all prepared samples was calculated by scherrer’s formula given as (iqbal, ahmad, meydan, & nlebedim, 2012). d=   cos 9.0 (1) d shows crystallite size, β shows full width at half maximum (fwhm), λ is x-ray's wavelength, and θ shows diffraction angle. the structural parameters such as lattice constant, cell volume, x-ray density, bulk density, and crystallite size were evaluated from the recorded data of xrd. all these parameters are listed in table 1. crystallite size exhibits abdul hameed, muhammad waqas khaliq 57 a non-linear behavior with the increasing contents of tb and cr in cobalt ferrite. the decrease in crystallite size has also been reported in the literature by including rare earth cations (rezlescu, rezlescu, pasnicu, & craus, 1994). the lattice constant increases from 8.372 å to 8.39 å with the increase of tb3+ and cr3+ concentration in the spinel lattice of cobalt ferrites. figure 2: xrd patterns of co1-xtbxfe2-ycryo4 (x = 0.00.10 and y = 0.00.5) ferrites the cell volume was also increased from 586 (å)3 to 590 (å)3. the slight increase in the lattice constant is attributed to the larger ionic radius of tb3+ (0.93 å) than co2+ (0.74 å) and smaller ionic radius of cr3+ (0.63 å) as compared to fe3+ (0.67 å) (b. cheng, 2006; john berchmans, kalai selvan, selva kumar, & augustin, 2004). the replacement of smaller cations (co) with the larger cations (tb) justified the increase in lattice constant. the bulk densities of all samples were observed to be smaller than x-ray densities, which revealed the presence of pores in these soft ferrites obtained in the preparation or sintering of the ferrite samples. the value of x-ray density increases from 4.79 to 5.09 g/cm3 with an increasing amount of dopants. it is also obvious from table 1 that bulk density increases from 3.68 to 3.93 g/cm3 with the increase of dopants content, and it might be because the tb ion has a higher atomic weight than the co cation. the porosity varies from 24.6 to 22.8 %. similar results were reported in the literature for rare earth substituted cobalt spinel ferrites (dascalu, popescu, feder, & caltun, 2013; tahar et al., 2008). table 1 crystallite size (d), lattice constant (ɑ), cell volume (vcell), x-ray density (ρx), bulk density (ρb), and porosity (p %) of co1-xtbxfe2-ycryo4 (x = 0.0-0.1, y=0.00.5) nano-ferrites composition d (nm) a (å) vcell (å3) ρx (gm/cm3) ρb (gm/cm3) p (%) x=0.00, y=0.0 44 8.372 586.8 4.79 3.68 23 x=0.02, y=0.1 43 8.374 587.2 4.86 3.72 23.5 x=0.04, y=0.2 39 8.377 587.8 4.97 3.75 24.5 x=0.06, y=0.3 41 8.382 588.9 5.01 3.78 24.6 x=0.08, y=0.4 32 8.386 589.7 5.06 3.84 24.1 x=0.10, y=0.5 28 8.390 590.6 5.09 3.93 22.8 3.3. magnetic properties m–h loops of pure and tb-cr co-doped cobalt ferrites were obtained up to an applied magnetic field of 10 koe and are exhibited in figures 3a to 3f. magnetic parameters, i.e., journal of materials and physical sciences 2(2), 2021 58 coercivity (hc), saturation magnetization (ms), and remanence (mr), were taken out from these loops and are tabulated in table 2. the ms can also be calculated using the law of approach to saturation (grossinger, 1981). all the fitted curves of saturation magnetization are calculated using this law at 300 k are shown in figures 4(a-f). all samples revealed high ms values while coercivity (hc) values were relatively low, indicating that all the materials showed strong magnetism (ozkaya et al., 2009). coercivity values range from a few hundred oersteds for entire materials, and these elucidate the intrinsic behavior of soft ferrites. it was noticed that co-doping of tb and cr in co soft ferrites substantially lowers the coercivity. this decrement in coercivity was attributed to the decrease of the magnetocrystalline anisotropy of co ferrite; as the concentration of co decreases that has a high value of magneto-crystalline anisotropy from other cations present in these materials (kambale, song, won, lee, & hur, 2012; ren & xu, 2014; sodaee, ghasemi, paimozd, paesano jr, & morisako, 2013). figure 3a: m-h loop of cofe2o4 ferrite figure 3b: m-h loop of co0.98tb0.02fe1.9cr0.1o4 ferrite abdul hameed, muhammad waqas khaliq 59 figure 3c: m-h loop of co0.96tb0.04fe1.8cr0.2o4 ferrite figure 3d: m-h loop of co0.94tb0.06fe1.7cr0.3o4 ferrite figure 3e: m-h loop of co0.92tb0.08fe1.6cr0.4o4 ferrites journal of materials and physical sciences 2(2), 2021 60 figure 3f: m-h loop of co0.90tb0.10fe1.5cr0.5o4 ferrite the coercive force can be co-related with crystallite size. the larger crystallites provide minimum pinning of domain walls due to the smaller volume fraction of the grain boundaries. it was found that crystallite size exhibits non-linear behavior by increasing doping concentration. similarly, coercivity first decreases from 425 oe to 364 oe, and later it increases for higher dopants concentration. the ms reduces from 62 to 51 emu/g by increasing the dopants concentration. the decrement in the ms can be associated with exchange interaction among tetrahedral cations (a-sites) and octahedral cations (b-sites). the decrease in the ms is due to the dilution of magnetization for tb3+ and cr3+ in the b-site (panneer muthuselvam & bhowmik, 2010; wells & ramana, 2013). when a small amount of these dopants are introduced in these ferrites, these paramagnetic cations tend to arrive in the b-sublattice (y. y. li, 1974) and substitute ferromagnetic co cations at b-sites. hence, the magnetization decreases, resulting in the ms decreases for all tb-cr co-doped ferrites (l. kumar & kar, 2012). the remanence reduces from 13.38 to 8.12 emu/g by increasing the contents of dopants. the fitted curves of ms, acquired from the law of approach to saturation, are calculated at 300 k for all samples and are shown in figures 4a to 4f. figure 4a: the fitted curve of ms at 300 k obtained from the law of approach to saturation for cofe2o4 ferrite abdul hameed, muhammad waqas khaliq 61 figure 4b: the fitted curve of ms at 300 k was obtained from the law of approach to saturation for co0.98tb0.02fe1.9cr0.1o4 ferrite figure 4c: the fitted curve of ms at 300 k was obtained from the law of approach to saturation for co0.96tb0.04fe1.8cr0.2o4 ferrite. figure 4d: the fitted curve of ms at 300 k was obtained from the law of approach to saturation for co0.94tb0.06fe1.7cr0.3o4 ferrite. journal of materials and physical sciences 2(2), 2021 62 figure 4e: the fitted curve of ms at 300 k was obtained from the law of approach to saturation for co0.92tb0.08fe1.6cr0.4o4 ferrite. figure 4f: the fitted curve of ms at 300 k was obtained from the law of approach to saturation for co0.90tb0.10fe1.5cr0.5o4 ferrite table 2 saturation magnetization (ms), remanence (mr) and coercivity (hc) for co1xtbxfe2-ycryo4 (x = 0.0-0.1, y=0.0-0.5) nano-ferrites composition ms (emu/g) mr (emu/g) hc (oe) x=0.00, y=0.0 62 13.38 425 x=0.02, y=0.1 61 10.96 397 x=0.04, y=0.2 59 10.11 398 x=0.06, y=0.3 58 8.12 365 x=0.08, y=0.4 56 9.10 399 x=0.10, y=0.5 51 8.29 409 3.4. dielectric properties ferrites are dipolar materials as they have fe2+ cations in the minority fe3+ cations in the majority. dipoles of fe3+-fe2+ align in the direction of the electric field. it can be seen from figure 5 that at a lower frequency, the dielectric constant (εꞌ) decreases quickly. still, it decreases gradually at the higher frequency region and becomes almost independent of frequency. in the literature, other researchers have reported a similar dielectric behavior abdul hameed, muhammad waqas khaliq 63 (d.r. patil, 2009; n. singh, 2011). in this research work, the movement of electrons between fe3+ cations and fe2+ cations and the movement of holes between ni2+ cations and ni3+ cations contributes to the local direction of electrons in the electric field, resulting in polarization. koop’s theory is helpful to interpret this fast decrement of dielectric constant at minimum frequency (koops, 1951). on the basis of koop’s phenomenological theory dielectric structure having inhomogeneous medium consisting of two layers and this is also ascribed to the maxwellwagner model (jacob, thankachan, xavier, & mohammed, 2013). this is evident from figure 5 that the dielectric constant is reduced by incorporating dopants (tb3+-cr3+). figure 5: dielectric constant (εꞌ) vs frequency for co1-xtbxfe2-ycryo4 (x = 0.0-0.1, y = 0.00.5) ferrites in ferrites, there are two losses, including magnetic loss and dielectric loss. figures 6 and 7 indicate the dielectric loss (εꞌꞌ) and tan loss of tb-cr doped cobalt ferrite. figure 7 shows that dielectric tan loss decreases by increasing the number of dopants. the dielectric loss initially decreases rapidly and then increases slowly, and the last composition exhibits strange behavior. the variation in dielectric losses is because of the ion shifting. the loss peak is usually observed when the frequency of the external electric field becomes equal to the hopping frequency of the electron between fe2+ and fe3+ ions. figure 6: dielectric loss (εꞌꞌ) vs frequency for co1-xtbxfe2-ycryo4 (x = 0.0-0.1, y = 0.00.5) ferrites journal of materials and physical sciences 2(2), 2021 64 the resonance phenomenon happens because of the matching of frequencies of external electric field and hopping frequency of transferring electrons. when dopants are incorporated in cobalt ferrite, it occupies the octahedral site, decreasing the number of cobalt and iron ions on that site. due to this, electrical conduction decreases (zhijian penga, 2011). ac conductivity was calculated using the following equation: σac= 2𝜋𝑓 ′ ′′𝑡𝑎𝑛𝛿 (2) figure 7: tan loss vs frequency of co1-xtbxfe2-ycryo4 (x=0.0-0.1,y=0.0-0.5) ferrites figure 8 shows that ac conductivity rises with the increase of doping contents of tb3+ cr3+. figure 8 reveals that ac conductivity rise with the rise in frequency. this behavior can be explained using maxwell wagner's models and koop's theory. based on these models, ferrites are called conducting grains separated by a thin resistive layer called grain boundaries. in the lower frequency region, grain boundaries are more active and contribute to conduction. in higher frequency regions, conductive grains increase conduction and hoping conduction (asif iqbal et al., 2014). peaking behavior is also observed beyond 1.5 ghz, which reveals the resonance phenomenon. the decrement in the ac conductivity with the increased dopants is ascribed to a decrease in the hoping frequency of electrons between fe2+ and fe3+. the decrease in ac conductivity may be described by grain size. since grain size declines for higher dopants concentration and hence grain boundaries become larger, ac conductivity declines. figure 8: ac conductivity vs frequency for co1-xtbxfe2-ycryo4 (x=0.0-0.1, y=0.00.5) ferrites abdul hameed, muhammad waqas khaliq 65 in ferrites, the conduction mechanism and relaxation behavior can be understood from the interpretation of the dielectric modulus. the real and imaginary parts of the dielectric modulus can be obtained using the following equations: m'=ε'/(ε'2+ε''2) (3) m''=ε''/(ε'2+ε''2) (4) the nature of real (m') and imaginary (m'') parts of electric modulus as a function of applied field frequency is significant to knowing the relaxation mechanism (asif iqbal et al., 2014). figure 9 and figure 10 indicate the real (m') and imaginary (m'') parts of the dielectric modulus as a function of applied frequency. m'' increases with the rise in the biasing oscillating applied electric field and reaches the highest value at some applied frequency called relaxation frequency. an oscillating frequency and applied field frequency become equal. according to these figures (9 &10), when the contents of dopants (tb3+cr3+) increased highest peaks in m'' shifts towards the lower frequency region. this decrease in maxima peak with increased doping concentration for different compositions suggests the contribution of the grain boundary resistance (pervaiz & gul, 2014). these graphs show the missing relaxation phenomenon in these doped cobalt ferrites associated with the relaxation process (pervaiz & gul, 2014). this may be the reason for low loss, which makes these ferrites bad conducting and low dielectric loss to be used in an instrument that absorbs electromagnetic radiation (asif iqbal et al., 2014). figure 9: real part of electric modulus vs frequency for co1-xtbxfe2-ycryo4 (x=0.00.1 and y = 0.00.5) ferrites figure 10: imaginary part of electric modulus vs frequency for co1-xtbxfe2-ycryo4 (x = 0.0-0.1 and y = 0.00.5) ferrites journal of materials and physical sciences 2(2), 2021 66 4. conclusion tb-cr substituted cobalt soft ferrites having the following compositions co1-xtbxfe2ycryo4 (x = 0.0-0.10, y = 0.0-0.5) were synthesized by solid-state reaction method. cofe2o4 has a single-phase cubic spinel structure, and all other doped compositions exhibited traces of the ortho phase (tbfeo3) and the cubic spinel phase. the 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(2011). effect of pr3 þdoping on magnetic and dielectric propertiesof ni–zn ferrites by ‘‘one-step synthesis’’. journal of magnetism and magnetic materials 323 (2011) 2513–2518, 323 (05-05-2011), 6. http://dx.doi.org/10.1016/j.jmmm.2013.10.056 http://dx.doi.org/10.1016/0304-8853(94)00309-2 http://dx.doi.org/10.1016/j.jmmm.2012.10.050 http://dx.doi.org/10.1016/j.jmmm.2008.06.031 http://dx.doi.org/10.1016/j.ceramint.2013.05.073 http://dx.doi.org/10.1016/j.matlet.2005.07.083 https://doi.org/10.52131/jmps.2020.0101.0001 1 journal of materials and physical sciences volume 1, number 1, 2020, pages 01 11 journal homepage: https://journals.internationalrasd.org/index.php/jmps synthesis and characterization of lanthanum doped co-zn spinel ferrites nanoparticles by sol-gel auto combustion method zaheer abbas gilani1, amir farooq1, h. m. noor ul huda khan asghar1*, muhammad khalid2 1 department of physics, balochistan university of information technology, engineering & management sciences, quetta 87300, pakistan 2 department of physics, university of karachi 24700, pakistan article info abstract article history: received: april 18, 2020 revised: may 28, 2020 accepted: june 28, 2020 available online: june 30, 2020 spinel ferrites nanoparticles play a significant role in our everyday lives. in the current work, la3+ doped co-zn ferrites with chemical formula co0.5zn0.5laxfe2-xo4 (x = 0.00 to x = 0.2 with step size 0.04) was effectively prepared by sol gel technique. the formation of fcc spinel structure was confirmed by x-ray diffraction (xrd) analysis. the average crystallite size were calculated to be in the 8 nm to 13 nm range. the lattice parameters were found to be decreased with the doping of lanthanum (la3+) contents. xray density is analyzed to increase as the concentration of (la3+) doping increases, this is due to the fact that la3+ ion has a higher molar weight than fe3+ ion. the spinel phase structure was affirmed by using ftir.the two main absorption bands ν1 and ν2 are referred to tetrahedral stretching band and octahedral stretching band respectively, is found to be in the range of at around 400-530 cm-1. spinel ferrites, such as co-zn spinel ferrites, have dielectric features that make them ideal for use in high-frequency applications. with new potential applications being investigated all the time. physical properties, synthesis method, as well as sintering temperature and time, are all important factors in regulating the properties of dielectric materials. the dielectric features were measured in the frequency of 1 mhz to 3 ghz range. lowered dielectric parameters studied across a higher frequency range recommend that such nano crystalline ferrites could be used to fabricate the equipment needed to perform at ghz frequencies. keywords: co-zn ferrite spinel ferrites nanocrystallite ferrites sol-gel xrd ftir dielectric properties © 2020 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author: noorulhudakhan@gmail.com 1. introduction the potential and theory of nano science and technology is focused on the fact that materials at the nanoscale have mechanical, chemical, electrical, magnetic, and optical properties that are completely different from bulk materials (mansoori, 2005). some of these characteristics are intermediate between those of the smallest constituents (such as particles and atoms) from which they can originate and those of microscopic level materials when contrasted to bulk materials. as nanoparticles are used in comparative applications, it shows that they have execution abilities. nanotechnology has a wide range of current and future applications, including bottom-up approaches in medicine, genetics, medicines, electronics, electricity, and the environment (mansoori & soelaiman, 2005). a stainless steel substance with magnetic characteristics which can be used in a wide variety of devices. ferrites are stiff, porous, metal, grey or black in color, and poly crystalline, made up of several smaller clusters. ferrites are made up of a specific mixture of fe2o3 and one https://journals.internationalrasd.org/index.php/jmps mailto:noorulhudakhan@gmail.com journal of materials and physical sciences 1(1), 2020 2 or more elements. the discovery of stones with an inclination to iron hundreds of years preceding the christ's birth began the history of ferrites. the massive wedge of these rocks was discovered in magnesia. these are being used as solvents in paintings at some stage during the paleozoic era. ferrites have the general formula mefe2o4 and me is a divalent metal ion in this case. the interconnected arrangement of covalently bonded oxygen anions and metallic ions is known as the ferrite structure. ferrites are commonly thought of as having a high tensile strength when compared to metals (matsushita et al., 2006). the most widely used ferrites are the spinel ferrites. spinel ferrites are an amazing family of oxides that modify the pattern of typical spinel ferrites (hill, craig, & gibbs, 1979). although a few mechanically significant spinels are organic, magnetite with general formula fe3o4 is a characteristic oxide that is still one of the most important and perhaps the most known with useful applications. spinels are ionic in nature. numerous aspects, including covalent-bonding impact and metal oxide cation crystalline lattice normalization energies, influence cation adherence to specific sites. the crystal structures of spinel ferrites with a net charge of 8, various types of cations sorting can occur to even out the anion's net negative charge (verweel & smit, 1971). spinel crystal structure was first discovered by bragg (bragg, 1915) and nishikawa (nishikawa, 1915) in 1915. the crystal structure of spinel ferrites with general formula ab2o4. the atoms of oxygen are arranged in a cubical arrangement, where a and b represents tetrahedral and octahedral sites of the crystal structure of spinel ferrites. the domain class fd3m is found in the majority of spinel compositions. m8fe16o32 is the formula, overall the oxygen anions in the cubic unit cell make up 96 interstitial spaces, and 64 and 32 a and b lattice sites. the cubic spinel structure ferrites unit-cell is moulded with 56 atoms and 32 of those are oxygen atoms, which are arranged in a cubic near stuffed structure, with 24 transition metals spread among 8 lattice site a and 16 lattice site b. completely accessible there were 64 a lattice sites, but only 8 are involved, and there are 32 accessible b lattice sites, but only 16 were involved to charge neutrality. spinel crystal structure can be categorized into regular, inverse, or intermediate spinel ferrites based on cation distribution between these a and b lattice sites. for regular spinel inversion parameter = 1, for inverse spinel inversion parameter = 0, and for intermediate ferrite δ ranges varies among these two acute ranges (sickafus, wills, & grimes, 1999). in spinel ferrites, not all interstitial sites are the same; lattice sites a are connected by four oxygen ions that are closest to each other. as a result, lattice sites a are referred to as tetrahedral sites. a tetrahedral site is formed by three atoms in a field contacting one another, with a fourth atom sitting on top in a trigonal arrangement. to maintain charge neutrality in the crystal structure, only 8 of the 64 a lattice sites are involved. the interstitial sites in octahedral lattice sites b in cubic spinel crystal structure are formed by the coordination of 6 closest oxygen particles. the sides of an octahedron are present in the oxygen particles at the lattice site b. 4 of the six particles are in a line, while the other two are in the trigonal position above and below the plane. only 16 of the 32 lattice sites b in a crystal structures are filled to maintain charge neutrality (smit, wijn, & ferrites, 1961). in the present study, we have developed a co-zn ferrites series by substitution of la3+ using the sol-gel method. we studied the different structural and dielectric properties by changing the concentration. 2. experimental procedure lanthanum substituted cobalt-zinc spinel ferrites with chemical formula co0.5zn0.5laxfe2-xo4 (x = 0.00, 0.04, 0.08, 0.12, 0.16, 0.20) were effectively prepared by using sol-gel technique. where x denotes varying proportion of impurity doped that is la3+. the chemicals used were cobalt (ii) nitrate hexa-hydrate [co (no3)2.6h2o] m.w = 291.03 made by sigma-aldrich, (99%), zinc nitrate [zn (no3)2.6h2o] m.w = 297.46, lanthanum nitrate [la (no3)3.6h2o] m.w = 433.02 made by merck-germany (99.9%), iron nitrate [fe (no3)3.9h2o] m.w = 404 made by gpr and citric acid [c6h8o7.h2o] (99.9%). the solutions of the samples were prepared in order to make the homogeneous mixture and magnetic stirrer rod was used to dissolve chemicals properly in distilled water. after preparation and properly mixing of solution proportionate forms of solutions in six different beakers were put it on the hotplate. to increasing the temperature between (90°c-120°c) for up to 2 hours. the materials inside the beakers are subjected to form gel at the bottom, which contributes to the formation of sol with the consistent increase in temperature. the zaheer abbas gilani, amir farooq, h. m. noor ul huda khan asghar, muhammad khalid 3 samples were burned due to increase in temperature to 200°c. the burned samples are subjected to properly grinded one by one in such a way that the samples became in the form of fine powder. after the samples were properly grinded, hydraulic press was used for pelleting by applying 07 ton compressed forced. after annealing the specific amount of the materials were taken out and make pellets for each samples by hydraulic press to applying 07 ton of force. after making the pellets the remaining samples are put into different tubes. different characterization techniques, such as xrd, ftir, dielectric, sem etc., were used to characterize the materials. 3. results and discussion 3.1. xrd analysis the x-ray diffraction pattern for all co0.5zn0.5laxfe2-xo4 (x= 0.0, 0,04,0.08, 0.12, 0.16, 0.2) spinel ferrite nano particles synthesized via sol–gel technique. the co-zn composites samples were sintered for 5 hours at 700°c. the crystal structure and crystalline phase pattern was identified using the xrd. which is a very helpful method for calculating crystalline parameters. the xrd most intense peak was reported at 2=35°, which is usually assumed to be an optimal intense peak for cubic crystal structure. all of the peaks are well matched with the peak of co-zn ferrite recorded in jcpds card number # 22-1086 and are listed respectively as (220), (311), (400), (422), (511), (440), (620) and (622). the positions and miller indices of the peaks show that a fcc spinel structure has formed. the fcc spinel structure is described by all of the peaks in the pattern, suggesting that the prepared ferrites had an fcc spinel structure. some impurity peaks obtained at 2=33°, the presence of these impurity peaks revealed that la3+ was insoluble in the octahedral site (gilani et al., 2015). the xrd pattern shown in figure 1. the debye scherrer formula was used to determine the average crystallite size (dm), given as: 𝐷𝑚 = 𝑘 𝑐𝑜𝑠 (1) where k = 0.9 for spinel ferrites,  = 1.54 å represents the x-ray beam wavelength, '' is the fwhm of the most intense peak and  is the angle of the diffraction of the most intense peak. the crystalline size was measured to be in 8 nm to 13 nm range, and was found to be very small. the size of the crystallites increases as the concentration of la3+ doping increases to be in the range of 8 nm (x=0.0) to 13 nm (x=0.20) [9,10]. figure. 1. xrd analysis of la3+ doped co-zn ferrites (x= 0.00 to x=0.20 with step size x= 0.04) journal of materials and physical sciences 1(1), 2020 4 the average lattice parameter 'a' can be calculated by the following formula given as: 𝑎 = 𝑑√ℎ2 + 𝑘2 + 𝑙2 (2) where’d’ is the crystal planes spacing and hkl represents the values of miller indices. the average lattice constant was measured for all samples to be in the range of 8.49 å to 8.56 å. the ionic radii of the ions la3+ and fe3+ were being used to explain the average lattice parameter 'a'. the average lattice parameter was found to be decreased with the la3+ doping contents (mustafa et al., 2020). x-ray density x can be measured by using the following formula: 𝜌𝑥 = 8𝑀 𝑁𝑎3 (3) where 'm' is the composition molecular weight, z=8 for spinel structure represent the number of molecules per unit cell, n is the avogadro no. (6.0221 × 1023) and a3 is a volume of the unit cell. x-ray density was calculated in the range of 5.06 g/cm3 to 5.51 g/cm3. the relation between x-ray density and concentration, the curve is almost linear, which mean the x-ray density increases as the amount of la3+ doping increases, because la3+ has a stronger molar weight than fe3+ (sheikh et al., 2019). the bulk density by size and mass of the pellets can be determined by using the following relation: 𝜌𝑚 = 𝑚 𝑣 (4) where 'm' represents mass and 'v' represents volume of the pellets. the bulk density were calculated from 2.94 g/cm3 to 3.51 g/cm3 range. the bulk density first increases then decreases and then again increases gradually due to the concentration of la3+ doping. consequently, the reduction in bulk density corresponds to the overall weight of pallets (khalid et al., 2021). the lattice strain is calculated by using the following formula: = 𝛽 4𝑡𝑎𝑛𝜃 (10−3) (5) where  is the angle of diffraction of the most intensity peak. lattice strain was calculated to be in the range of 8.87×10-3 to 13.68×10-3. the lattice strain is found to be decreases as the amount of la3+ doping increases. the higher value of lattice strain was observed at the value of x = 0.0. micro-strain can be determined by using the following relation given as: 𝑀𝑖𝑐𝑟𝑜 − 𝑠𝑡𝑟𝑎𝑖𝑛 = 𝛽𝑐𝑜𝑠𝜃 4 (10−3) (6) micro-strain was calculated to be in the range of 2.66×10-3 to 4.11×10-3. the microstrain is found to be decreases as the concentration of la3+ doping increases. the higher value of micro-strain was observed at the value of x = 0.0. dislocation density of the prepared nanoparticles can be determined by using the following equation given as: 𝛿 = 1 𝐷2 (1015) (7) where 'd' is the crystalline size. the stacking fault of the prepared ferrites can be determined by using the following relation given as: 𝑆𝑡𝑎𝑐𝑘𝑖𝑛𝑔 𝐹𝑎𝑢𝑙𝑡 (𝑆𝐹) = 2𝜋2 45√3𝑡𝑎𝑛𝜃 (8) the stacking fault was calculated to be in the range of 0.4510 to 0.4538. the stacking fault first increases then gradually decreases which may be due to the concentration of la3+ doping. the maximum value of stacking fault is found to be at the value of x= 0.04. table 1 shows the different structural parameters of xrd analysis with different doping concentration zaheer abbas gilani, amir farooq, h. m. noor ul huda khan asghar, muhammad khalid 5 table 1 different parameters for crystal composition of la3+ doped co-zn ferrites (x= 0.00 to x=0.20 with step size x= 0.04) parameters x = 0.0 x = 0.04 x = 0.08 x = 0.12 x = 0.16 x = 0.20 crystalline size (nm) 8.435 10.267 10.021 11.096 11.398 13.009 lattice constant a(å) 8.545 8.566 8.556 8.525 8.495 8.492 cell volume (a3) 624.006 628.573 626.333 619.659 613.126 612.392 x-ray density (gram/cm3) 5.0635 5.0969 5.1856 5.3127 5.4413 5.5199 bulk density (gram/cm3) 2.947 3.352 3.449 3.159 3.144 3.512 lattice-strain (10-3) 13.683 11.554 11.641 10.442 10.182 8.870 micro-strain (lines-2/m-4) (10-3) 4.108 3.375 3.458 3.123 3.0399 2.663 dislocation-density (lines/m) (1015) 14.055 9.486 9.958 8.122 7.697 5.909 stacking fault 0.451 0.454 0.4536 0.452 0.4523 0.4509 3.2. ftir spectroscopy we used ftir to confirm the spinel phase structure of all the samples. we learned about cations distribution in all sites (tetrahedral and octahedral) in a crystal from ftir, as well as chemical changes in the composition. in every concentration of co0.5zn0.5laxfe2-xo4 (x=0.00, 0.04, 0.08, 0.12, 0.16, 0.20) ferrites, the spinel phase structure was affirmed by using ftir. the features of spinel crystal structure are classified into two primary frequency bands one is high frequency band ν1 (approx. 500 cm-1) and the other one is the low frequency band ν2 (approx. 400 cm-1). because of the tetrahedral site of inherent stretching vibration, the absorption peaks are referred to as higher frequency bands ν1. the term "lower frequency bands ν2" refers to octahedral stretching bands. the ftir spectra are shown in figure 2 was ranged between 400 to 1000 cm-1. the table shows the various frequencies that can be achieved by increasing the la+3 content (gilani et al., 2015). the higher frequency bands ν1 varied from 535 to 544 cm-1 whereas in the lower frequency bands ν2 values remain same which shows that the frequency band remain static. the strength of absorption bands ν1 and ν2 changes due to the difference in stretching vibrations of fe+3o-2 at tetrahedral lattice sites and octahedral lattice sites. figure 2. ftir spectra of la3+ doped co-zn ferrites (x= 0.00 to x=0.20 with step size x= 0.04) furthermore, figure 2 shows that as the amount of lanthanum in the nanoparticles increases, the frequency band shifts slightly, which could be due to grain size and lattice parameters. the fe+3-o-2 stretching vibrations were caused by changes in lattice constant, journal of materials and physical sciences 1(1), 2020 6 resulting in a shift in band position. furthermore, when six sets of data are compared, it is revealed that as lanthanum concentration rises, the intensity of the ν1 absorption band increases as well, whereas the intensity of the ν2 absorption band remains unchanged (shahzadi et al., 2020). the values of force constants, denoted by kt and kօ for tetrahedral and octahedral sites, were computed from table 2 using the following formulas: kօcta = 0.942128 m (ν2)2 / (m+32) (9) ktetra = √2 kօ ν1/ ν2 (10) where ν1 and ν2 are high frequency and low frequency bands respectively, m shows the molecular weight of the composition. the values of tetrahedral and octahedral radii were also determined using the following formulas: rtetra = a √3 (u 0.25) ro (11) rocta = a (5/8-u) ro (12) where rtetra and rocta represents the tetrahedral and octahedral radii respectively, ‘a’ is the lattice parameter and 'u' is the oxygen position parameter. for fcc structure the value of oxygen parameters is 0.375. the values of different ftir parameters were computed in below table 2. table 2 different structural parameters involved in ftir spectra parameters x = 0.00 x = 0.04 x = 0.08 x = 0.12 x = 0.16 x = 0.20 molecular weight (g/mole) 237 241 244 247 251 254 ν1 /cm −1 535 535 540 544 535 542 ν2 /cm −1 406 406 406 406 406 406 kocta (dyne/cm 2) ×105 1.36881 1.37105 1.37323 1.37537 1.37745 1.37949 ktetra (dyne/cm 2) ×105 2.55085 2.55502 2.58301 2.60619 2.56696 2.60439 rocta 0.081634 0.082154 0.081899 0.081136 0.080385 0.080299 rtetra 0.0530122 0.0534625 0.0532419 0.0525816 0.0519306 0.0518571 3.3. dielectric properties table 3 different dielectric properties of la3+ doped co-zn ferrites (x= 0.00 to x=0.20) parameters frequency x =0.0 x =0.04 x=0.08 x =0.12 x =0.16 x =0.2 dielectric constant 1 mhz 5.9822 5.3315 5.5405 5.9616 4.6260 3.9242 1 ghz 6.2626 5.5560 5.2872 5.3028 4.9767 4.9546 3 ghz 5.6709 5.28581 4.48815 4.9839 4.34863 4.6512 dielectric loss 1 mhz -0.494 -0.921 -0.065 -0.081 -0.198 -0.285 1 ghz 0.0367 0.1839 0.0281 0.2808 0.0953 0.1844 3 ghz 0.27442 0.25499 0.11167 0.12388 0.13794 0.12857 tangent loss 1 mhz -0.0827 -0.1728 -0.0118 -0.01375 -0.0428 -0.0726 1 ghz 0.0058 0.03311 0.0053 0.05297 0.0191 0.0372 3 ghz 0.04839 0.04824 0.02488 0.02486 0.03172 0.02764 ac conductivity 1mhz 2.56298 e-05 1.64593e -05 3.07773 e-05 5.77269e -05 7.79359e -06 2.41441 e-05 1ghz 0.00148 6 0.011194 0.00156 1 0.010787 0.004610 0.00930 3 3 ghz 0.04398 8 0.035354 0.02097 7 0.024476 0.027272 2 0.02264 72 spinel ferrites, such as co-zn spinel ferrites, have dielectric features that make them ideal for use in high-frequency instruments, and new applications are being investigated all the time. physical properties, synthesis method, as well as sintering temperature and time, are all important factors in regulating the properties of dielectric materials. the dielectric features such as dielectric constant, permit loss, permittan, real and imaginary components of impedance, electric modulus and ac conductivity of la-doped co-zn spinel ferrites having chemical formula co0.5zn0.5laxfe2-xo4 (x=0.0, 0.04, 0.08, 0.12, 0.16, and zaheer abbas gilani, amir farooq, h. m. noor ul huda khan asghar, muhammad khalid 7 0.20) were measured in the 1 mhz to 3 ghz frequency range in the present work (junaid et al., 2016) and are interpreted in the table 3. 3.3.1.dielectric constant and dielectric loss dielectric constant (ɛ') and dielectric loss (ɛ") can be calculated by using the formulas given as: ′ = 𝑡 𝜔𝐴ɛօ × 𝒁" (𝒁′𝟐 +𝒁"𝟐) (13) " = 𝑡 𝜔𝐴ɛօ × 𝑍′ (𝑍′2 +𝑍"2) (14) where t is the thickness of pellets, 'a' is the area of the pellets surface, 'ω' is the angular frequency, ɛօ is the permittivity of free space (8.85 × 10-12), z' and z" are the real and imaginary impedance respectively. figure 3: (a) dielectric constant vs. frequency graph (b). dielectric loss vs. frequency graph figure 3(a) shows the dielectric constant graph for the frequency range of 1 mhz to 3 ghz, with various concentrations of la3+. the results showed that the dielectric constant rises with increasing the doping of la3+. it decreases precipitously for all composition in the lower frequency region with increasing the frequency. dispersion is caused by a decrease in dielectric constant with increasing frequency, which occurs as a function of the applied field at lower frequencies. the inter-facial polarization assumed by the maxwell-wagner model can be used to describe dielectric dispersion in ferrites. ferrites have a dielectric structure with good conducting grains isolated by weak conductor grain boundary. electron hopping between fe3+ and fe2+ causes electrons to pile up at grain boundaries, causing polarization in ferrites (khan et al., 2020). consequently, at low frequencies, electrons hoping between equivalent atoms ions (fe3+-fe2+) generates strong polarization and thus increases the dielectric constant. furthermore, as the electrons' hoping frequency is gradually increased, the electrons' exchange rate decreases, and the dielectric constant value decreases as well. dielectric loss in ferrites is primarily caused by electron hopping and defect dipoles. electron hopping causes dielectric loss only at very low frequencies. the effect of electron hopping decreases with increasing frequency, and thus the dielectric loss in the high frequency field decreases, figure 3(b) depicts it. charged distortion dipoles lead to dielectric loss in the high frequency range. the dielectric loss also has a peaking pattern, as shown in figure 3(b) (malik et al., 2014). journal of materials and physical sciences 1(1), 2020 8 3.3.2.tangent loss and ac conductivity figure 4: (a) tangent loss as a function of frequency (b). ac conductivity as a function of frequency the tangent loss (tan) specifies the rate of energy loss in dielectric materials. the tangent loss (tan) can be calculated using the formula below: 𝑡𝑎𝑛𝛿 = ɛ" ɛ′ (15) figure 4(a) depicts the tangent loss variance for frequencies ranging from 1 mhz to 3 ghz with various la3+ concentrations. it has been seen that the dielectric constant decreases as the applied frequency rises. permittan is greatest when the applied ac electric field is smaller than the hopping frequency, however, it is minimal when the electrons' hopping frequency is so high that they do not follow the applied electric field. permittan is high at low frequencies, as seen in figure 4(a), and it exponentially decreases as frequency is increased. the low tangent loss of nanoferrites is significant in a variety of applications (parveen et al., 2019). one of the most important properties of dielectric materials is ac conductivity. at room temperature, the ac conductivity of prepared ferrites of la3+ doped co-zn ferrites (x= 0.00 to x=0.20 with step size x= 0.04) with respect to frequency from 1 mhz to 3 ghz range can be calculated by the following formula: 𝜎𝑎𝑐 = 𝑡 𝐴 × 𝑍′ (𝑍′2+𝑍"2) (16) where t represents the thickness of the pellets, a represents the pellets surface area, and z' and z" represent the real and imaginary parts of impedance, respectively. in figure 5 the graph exhibit the dispersion at higher frequency region. the conductivity of all materials is minimal at low frequencies region. thin conducting grain-barrier layers separated the grains in spinel ferrites. the ac conductivity is influenced by the resistive behaviour of grain boundaries. figure 4(b) depicts, the minimal acconductivity in the low frequency range can be due to the higher resistance of the grain-boundaries, because of charge carrier exchange (hopping) between fe2+ and fe3+ ions at octahedral sites, the grains are conductive in the high frequency field. as a result, the hopping frequency rises as the applied electric field frequency rises, and the ac conductivity rises (mustafa et al., 2020). zaheer abbas gilani, amir farooq, h. m. noor ul huda khan asghar, muhammad khalid 9 3.3.3.real and imaginary impedance figure 5(a). real parts of impedance as a function of log f (b). imaginary parts of impedance as a function of log f the applied frequency has a large impact on real and imaginary components of impedance. figure 5(a) and figure 5(b) depict the impedance with respect to frequency from 1 mhz to 3 ghz range. the following relations can be used to determine real impedance (z') and imaginary of impedance (z") z' = r = |z| cosz (17) z" = x = |z| sinz (18) the resistive behaviour of grain barriers due to inter-facial polarization is recorded in the low-frequency region for all compositions, resulting in a high impedance. impedance analysis is showing the real and imaginary impedance decrease with increasing the applied frequency and impedance curves merge with each other at high frequency region, because of the conductive behaviour of grains in the higher-frequency field, the impedance is quite low (khalid et al., 2021; mustafa et al., 2020). 3.3.4.real and imaginary electric modulus figure 6: (a)real electric modulus as a function of frequency (b). imaginary electric modulus vs frequency the electric modulus has an effect on the dielectric properties of a material. modulus features are used to investigate the role of grains and grain barriers in a particular frequency range. charge carrier and stimulation behaviour of spinel ferrites can be studied using the electric modulus. the real and imaginary parts of the electric modulus in the frequency region of 1 mhz to 3 ghz were calculated using the formulas below: journal of materials and physical sciences 1(1), 2020 10 m' = ɛ'/ (ɛ'2+ ɛ"2) (19) m" = ɛ"/ (ɛ'2+ ɛ"2) (20) where ɛ' is the real dielectric permittivity or dielectric constant and ɛ" is the imaginary dielectric permittivity or dielectric loss. firstly, the real and imaginary components of the electric modulus have quite lower values in the low-frequency field. electric modulus analysis is showing the real and imaginary parts of electric modulus increase with increasing the frequency of applied field, while the electric modulus become maximum at high frequency region (khalid et al., 2021; mustafa et al., 2020). the different calculated values of impedance and electric modulus are depicted in table 4. table 4 impedance, modulus and ac conductivity of la3+ doped co-zn ferrites (x=0.00 to x=0.20 with step size x=0.04) parameters frequency x = 0.00 x = 0.04 x = 0.08 x = 0.12 x = 0.16 x = 0.2 z' (ohm) 1mhz 8.87e+03 7.38e+03 1.26e+04 2.40e+04 3.79e+03 1.20e+04 1ghz 4.69e-01 4.13e+00 6.22e-01 4.17e+00 1.99e+00 4.03e+00 3 ghz 1.79e+00 1.58e+00 1.16e+00 1.20e+00 1.58e+00 1.21e+00 z" (ohm) 1mhz 9.92e+04 1.13e+05 1.08e+05 1.06e+05 1.18e+05 1.19e+05 1ghz 9.51e+01 1.03e+02 1.07e+02 1.05e+02 1.11e+02 1.11e+02 3 ghz 3.41e+01 3.57e+01 3.98e+01 3.75e+01 4.07e+01 3.92e+01 m' 1mhz 0.192625 0.219643 0.208866 0.206758 0.229126 0.231046 1ghz 0.185804 0.200621 0.208731 0.205496 0.217077 0.217571 3 ghz 0.198598 0.2081701 0.232129 0.2186862 0.2373542 0.2282571 m" 1mhz 0.017229 0.014332 0.024463 0.046607 0.007361 0.023403 1ghz 0.000916 0.008065 0.001215 0.008154 0.003884 0.007881 3 ghz 0.010423 0.009196 0.006778 0.007099 0.009218 0.007076 4. conclusions spinel ferrites nanoparticles play a significant role in our everyday lives and used in variety of application such as medical industries, nano electronics, and waste water treatment etc. lanthanum (la3+) substituted co-zn nanoferrites with general formula co0.5zn0.5laxfe2-xo4 (x = 0.00 to x = 0.20 with step size 0.04) was effectively synthesized via sol-gel technique, that is the easiest way to synthesis of such types of nano ferrites. the xrd process was used to examine crystal structure and crystalline phase formation, which is a very helpful method for calculating crystalline features such as crystalline size, lattice constant, lattice strain, micro-strain, x-ray density, bulk density and stacking fault. the xrd most intense peak was reported at 2=35°, which is usually assumed to be an optimal intense peak for cubic crystal structure. the positions and miller indices of the peaks show that a fcc spinel structure has formed. the spinel phase structure was affirmed by using ftir. the features of spinel structure are classified into two primary frequency bands one is the higher frequency band ν1 (approx. 500 cm-1) and the other one is the lower frequency band ν2 (approx. 400 cm-1). because of the tetrahedral site of inherent stretching vibration, the absorption peaks are referred to as higher frequency bands ν1. the term "lower frequency bands ν2" refers to octahedral stretching bands. spinel ferrites, such as co-zn spinel ferrites, have dielectric features that make them ideal for use in high-frequency instruments, and new applications are being investigated all the time. physical properties, synthesis method, as well as sintering temperature and time, are all important factors in regulating the properties of dielectric materials. the dielectric properties of la-doped co-zn spinel ferrites were measured in the frequency of 1 mhz to 3 ghz range. the lowered dielectric features identified across a higher frequency range recommend that such nano crystalline ferrites could be used to fabricate the equipment needed to perform at ghz frequencies. acknowledgement we are grateful to oric of balochistan university of information technology, engineering and management sciences (buitems), quetta pakistan. zaheer abbas gilani, amir farooq, h. m. noor ul huda khan asghar, muhammad khalid 11 reference bragg, w. h. (1915). xxx. the structure of the spinel group of crystals. the london, edinburgh, and dublin philosophical magazine and journal of science, 30(176), 305315. gilani, z. a., warsi, m. f., khan, m. a., shakir, i., shahid, m., & anjum, m. n. (2015). impacts of neodymium on structural, spectral and dielectric properties of lini0. 5fe2o4 nanocrystalline ferrites fabricated via micro-emulsion technique. physica e: low-dimensional systems and nanostructures, 73, 169-174. hill, r. j., craig, j. r., & gibbs, g. (1979). systematics of the spinel structure type. physics and chemistry of minerals, 4(4), 317-339. khalid, m., chandio, a. d., akhtar, m. s., khan, j. k., mustafa, g., channa, n. u., & gilani, z. a. (2021). aluminum substitution in ni-co based spinel ferrite nanoparticles by sol–gel auto-combustion method. journal of electronic materials, 50(6), 3302-3311. khan, j. k., khalid, m., chandio, a. d., shahzadi, k., uddin, z., mustafa, g., . . . gilani, z. a. (2020). properties of al 3+ substituted nickel ferrite (nial x fe 2-x o 4) nanoparticles synthesised using wet sol-gel auto-combustion. journal of sol-gel science and technology, 1-12. malik, h., mahmood, a., mahmood, k., lodhi, m. y., warsi, m. f., shakir, i., . . . khan, m. a. (2014). influence of cobalt substitution on the magnetic properties of zinc nanocrystals synthesized via micro-emulsion route. ceramics international, 40(7), 9439-9444. mansoori, g. a. (2005). principles of nanotechnology: molecular-based study of condensed matter in small systems: world scientific. mansoori, g. a., & soelaiman, t. f. (2005). nanotechnology—an introduction for the standards community. journal of astm international, 2(6), 1-22. matsushita, n., kondo, k., yoshida, s., tada, m., yoshimura, m., & abe, m. (2006). ni-zn ferrite films synthesized from aqueous solution usable for sheet-type conducted noise suppressors in ghz range. journal of electroceramics, 16(4), 557-560. mustafa, g., khalid, m., chandio, a. d., shahzadi, k., uddin, z., khan, j. k., . . . gilani, z. a. (2020). dielectric, impedance, and modulus spectroscopic studies of lanthanumdoped nickel spinel ferrites nila x fe 2-x o 4 nanoparticles. journal of sol-gel science and technology, 1-10. nishikawa, s. (1915). structure of some crystals of spinel group. proceedings of the tokyo mathematico-physical society. 2nd series, 8(7), 199-209_191. parveen, a., khalid, m., gilani, z. a., aslam, s., saleem, m., shaikh, f. a., & rehman, j. (2019). dielectric, impedance and modulus spectroscopic studies of co 0.3 cd 0.7 zn 1.5 x fe 2− x o 4 nanoparticles. applied physics a, 125(10), 1-11. shahzadi, k., chandio, a. d., mustafa, g., khalid, m., khan, j. k., akhtar, m. s., & gilani, z. a. (2020). impact of aluminum substitution on the structural and dielectric properties of ni–cu spinel ferrite nanoparticles synthesized via sol–gel route. optical and quantum electronics, 52(4), 1-17. sheikh, f. a., khalid, m., shifa, m. s., aslam, s., perveen, a., ur rehman, j., . . . gilani, z. a. (2019). effects of bismuth on structural and dielectric properties of cobaltcadmium spinel ferrites fabricated via micro-emulsion route. chinese physics b, 28(8), 088701. sickafus, k. e., wills, j. m., & grimes, n. w. (1999). structure of spinel. journal of the american ceramic society, 82(12), 3279-3292. smit, j., wijn, h., & ferrites, l. (1961). bibliothèque technique philips. dunod, paris. verweel, j., & smit, j. (1971). ferrites at radio frequencies. magnetic properties of materials(13), 64. https://doi.org/10.52131/jmps.2022.0302.0030 96 journal of materials and physical sciences volume 3, number 2, 2022, pages 96 108 journal homepage: https://journals.internationalrasd.org/index.php/jmps synthesis and characterization of rare earth doped ferrite / polyethylene oxide nanocomposites muhammad ishfaq1, mahvish gul2, hatem alamri3, gulfam nasar4*, faseeh ur raheem5 1 govt. graduate college chishtian, bahawalnagar, pakistan 2 department of chemistry, the islamia university of bahawalpur, bahawalpur 63100, pakistan 3 umm al-qura university makkah, saudi arabia 4 department of chemistry, balochistan university of information technoogy, engineering and management sciences, quetta, pakistan 5 institute of physics, the islamia university of bahawalpur, bahawalpur, pakistan article info abstract article history: received: november 19, 2022 revised: december 15, 2022 accepted: december 30, 2022 available online: december 31, 2022 nano-sized li0.5ni0.48tb0.02dy0.1fe1.9o4 spinel ferrite nanoparticles were synthesized employing the micro-emulsion synthesis method. polyethylene oxide was prepared through in-situ polymerization route. the ferrite-polymer nanocomposites have been synthesized by combining li0.5ni0.48tb0.02dy0.1fe1.9o4 ferrite with polyethylene oxide polymer. spectral, structural, morphological, and dielectric properties of the prepared nano-ferrite powders as well as nanocomposites were investigated by “x-ray diffraction analysis” (xrd), “scanning electron microscopy” (sem), “fourier transform infrared spectroscopy” (ftir) and dielectric measurements. xrd analysis confirmed the synthesis of single-phase spinel structure only. the dielectric parameter was augmented with an increase of ferrite amount. ftir spectra confirmed the existence of interactions between polyethylene oxide and ferrite particles. sem study revealed that the nanocomposites comprised core/shell structure and inhomogeneous distribution of grain size. the dielectric parameters such as “real part of dielectric constant” (έ), “imaginary part of dielectric constant” (ɛ"), “tan loss”, “ac conductivity” and “quality factor” were investigated in the required range of frequency; that is, 1 mhz – 3 ghz. the peaking behavior has been observed for real (εꞌ) and “imaginary (εꞌꞌ) parts of dielectric constant” and “dielectric loss” (tanδ). “the peaking behavior” was detected beyond 1.5 ghz. a decrease in “the dielectric constants” and “dielectric loss” was found to with the increasing frequency. dielectric parameters have been well elucidated by explaining “debyetype relaxation model” in agreement with two layer “koop's phenomenological theory”. the present investigated samples might have potential applications in high frequency. keywords: ferrite-polymer nanocomposites polyethylene oxide ftir xrd dielectric properties sem © 2022 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: gulfam.nasar@buitms.edu.pk 1. introduction ferrites and oxides possess magnetic properties which have been a matter of great interest and have been studied extensively (rinkevich, korolev, samoylovich, klescheva, & perov, 2016). magnetic properties of the oxide nanoparticles are elucidated to set up a logical connection between the magnetic behavior and the nanoscale size. superparamagnetic properties have been observed by the magnetite nanoparticles prepared at the room temperature by co-precipitation method (kim & shima, 2007). magnetic oxides are applied effectively in a variety of technological fields, including water treatment and https://journals.internationalrasd.org/index.php/jmps mailto:gulfam.nasar@buitms.edu.pk muhammad ishfaq, mahvish gul, hatem alamri, gulfam nasar, faseeh ur raheem 97 environmental protection. using this technique, huge amount of water can be treated in a relatively very short time and more effectively (qi, huang, yan, li, & pan, 2015). the nanocomposites of “zinc ferrite-reduced graphene oxide” (zf-rgo) have been able to remove toxic contaminations very effectively using their high adsorption capability. the adsorption of a magnetic ferrite is attributed to its enhanced magnetic properties (fei, wang, zhong, & su, 2016). the applicability of nanomaterials could possibly be enhanced by varying the nanoparticles’ size(nasar et al., 2016). the size of nanoparticles has a direct connection with the physical properties (choudhry et al., 2015). perovskites (the metal oxides with general formula abo3) have been found very useful in several technological applications due to their unique properties (kammer hansen, 2013; li, qiu, wang, jiang, & xu, 2008). polymer nanocomposites with magnetic materials form a prominent class of material science, in which nanoparticles of magnetic materials are entrenched in polymer matrix (ahmed, okasha, mansour, & el-dek, 2010). the nanocomposites thus formed possess a great capability of applications like electromagnetic interference suppression, drug discharge (yinglin et al., 2014), industrial automatization (cheng, zhang, yi, ye, & xia, 2008) and electromagnetic devices (varshney et al., 2012). polymerferrite nanocomposites have been finding special attention due to their wider applicability in various advanced devices; for example fuel cell (ahmed et al., 2010), high performance batteries (salafsky, 1999) , supercapacitor (awadhia, patel, & agrawal, 2006) and sensors (ashis, sukanta, amitabha, & de, 2004). polymers serve as preferable matrix due to their binding properties and stabilization (awadhia et al., 2006). polymer matrix can build up a good interaction with ferrite nanoparticles and this interaction is attributed to formation of chemical or temporary bonds e.g., hydrogen bonding between the two components of the composite material. normally extend of magnetization of the nanocomposite has an inverse relation with the ferrite concentration (sankara rao et al., 2015). the magnetic properties of given nanocomposites are altered by varying the concentration of the ferrites (azhar khan et al., 2015). quite a large number of scientific studies have been reported on ferrite-polymer nanocomposites such as sm substituted lithium nickel ferrite-polyaniline nanocomposites as soft magnetic material (li, jiang, & xu, 2007), polyaniline-lini ferrite composites synthesized by in situ polymerization of aniline (jiang, li, & xu, 2007), cobalt ferrite/polyvinyl alcohol nanocomposites (mirzaee, farjami shayesteh, & mahdavifar, 2014), cobalt ferrites nanoparticles with polymethyl methacrylate (pmma) (hannour et al., 2014) have been studied theoretically and experimentally. the ferrite polymer composites with varying compositions of ferrites or matrices have been synthesized using polymers, copolymers, conducting (feller, bruzaud, & grohens, 2004) and non-conducting (seo, rhee, & park, 2011) polymers including crystalline (castel et al., 2009) and amorphous fillers (abbas, dixit, chatterjee, & goel, 2007). these composites exhibited very auspicious properties which make them fit to be used in electrical applications, as effective emi shielding materials (huang et al., 2007), medical instruments, radar system, high-speed wireless systems, satellite communications etc. (bueno, gregori, & nóbrega, 2008). till now, various composites have been used for variety of applications. however, rare earth doped li-ni ferrite (li0.5ni0.48tb0.02dy0.1fe1.90o4) with polyethylene oxide polymer is not discussed. in present work, micro-emulsion method was employed to synthesize li0.5ni0.48tb0.02dy0.1fe1.90o4 ferrite and “in situ polymerization method” was taken into consideration to prepare ferrite-polymer nanocomposites. in this study we have explored the effects of ferrite concentration in the polymer matrix on the structural, morphological, spectral, and dielectric properties of lithium-nickel rare earth doped ferrite-polymer nanocomposites. the main aim of the current research is to explain the usefulness of the nanocomposites in high frequency devices applications. 2. experimental procedure 2.1. materials lithium chloride, nickel (ii) chloride hexahydrate, terbium heptoxide, dysprosium nitrate hydrate, iron (iii) chloride, cetyltrimethylammonium bromide (ctab), aqueous ammonia and de-ionized water. journal of materials and physical sciences 3(2), 2022 98 2.2. synthesis of li0.5ni0.48tb0.02dyxfe2-xo4 nanoparticles different amounts of metal salt solutions were added to form various compositions of li0.5ni0.48tb0.02dyxfe2-xo4, where x = 0, 0.05, 0.1, 0.15, 0.2. appropriate concentration of salt solutions of li, ni, tb, dy and fe were prepared and mixed with magnetic stirrer at 5060 °c. 0.3 molar aq. solution of ctab was added to this mixture. the ph of prepared solution was sustained up to a level of 10 by a continuous slow addition of aqueous solution of ammonia. thereafter, all samples were stirred for six hours and were kept overnight to ensure complete settling down of the precipitates, which were later washed using “deionized water” until ph ~ 7 was attained. the washed contents were heat dried and ground followed by annealing for eight hours at 980 °c to remove any possible traces of ctab and impurities of organic compounds. 2.3. preparation of nanocomposites initially, 60 ml water was heated in a beaker at 50 °c and 1g pre-weighed polyethylene oxide was added slowly into it with continuous and vigorous stirring for three hours. at this stage 0.1, 0.2, 0.3, 0.4 and 0.5 g pre-weighed ferrite was added slowly into solution, with continuous stirring. the temperature of homogenous solution was kept at 60 °c along with steady stirring to obtain thick gel of polymer nanocomposites. the gels were converted into films by evaporation at room temperature in a petri dish. on drying, films were detached from the petri plates for characterization. 2.4. characterization techniques the measured xrd plots of li0.5ni0.48tb0.02dyxfe2-xo4 nano-structured ferrite and their nano-composites were recorded on diffractometer model “philips-x” pert-pro 3040 / 60” taking copper-kα as “primary source of radiation” to examine the development of phase of the prepared materials. average crystallite size (d) of the given prepared nanomaterials inspected on the basis of “line broadening peaks of x-ray diffraction” and determined through the “scherrer’s formula”: d = kλ / β cosθ (1) here d labels the “average size of crystallite” of the particles under examination, k is the “scherrer’s constant” is equal to 0.89, λ denotes to the wavelength of applied x-ray beam” used, β corresponds to the “full-width at half maxima of xrd peaks” (fwhm) and θ = “bragg’s angle of diffraction” (cullity, 1978). “fourier transformation infrared spectroscopy” (ftir) was employed using “tensor 27 spectrometer”. the spectra of ftir were used to determine all types of organic, functional groups in organic materials, various types of inorganic compounds and molecular composition of surfaces. all frequencies are simultaneously observed by ftir spectroscopy (griffiths, 1986). the morphological studies of ferrite-polymer nanocomposites were executed using electron scope model: “jeol jsm6490a”. the purpose of the sem examination was to know their surface morphology and to make an estimation of particle size. the dielectric measurement was performed and evaluated using “4287/arf lcr meter” for frequency ranges from 1 mhz to 3 ghz. the dielectric behavior of the synthesized samples was investigated as a function of frequency and concentration. the frequency range was 1mhz3ghz. every material has unique electrical characteristics and it depends on its dielectric properties, which are significant for designing the material for specific application (goldman, 1990). 3. results and discussion 3.1. structural analysis “x-ray diffraction patterns” of li0.5ni0.48tb0.02dy0.0.02fe1.9o4 ferrite/polyethylene oxide (peo) nanocomposites are shown in fig.1. the compositions of all the samples under investigation and their ferrite-polymer ratios are tabulated in table 1. all these peaks were clearly matched and confirmed the “single phase spinel structure” using the results of x-ray diffraction. the peak with the maximum intensity of all sample is identified with hkl (311) muhammad ishfaq, mahvish gul, hatem alamri, gulfam nasar, faseeh ur raheem 99 (ali et al., 2014). the secondary trace of ortho-rhombic phase is appeared at 33° (labeled by * in fig 1) which is identified as dyfeo3. the appearance of secondary peak is attributed to excess of dy3+ ions because it possesses larger ionic radii than that of the host ions. the results revealed that substitution of little amount of dy+3 ions into the structure of spinel ferrites replace ferric fe3+ ions on the “octahedral-sites” obeying the vegardʼs law. the average lattice constant was observed to 8.329 å. the calculated crystallite size lies within the range 34-47 nm. the lithium and nickel ions have preference to go “tetrahedral sites” and ferric fe3+ ions are disseminated between “tetrahedral and octahedral sites” (al-hilli, li, & kassim, 2009). figure 1: xrd patterns of li0.5ni0.48tb0.02dy0.0.02fe1.9o4 ferrite/peo nanocomposites “nelson-riley function” was empyed to find out the average value of “lattice constant” (a). the average lattice constant of li0.5ni0.48tb0.02dy0.0.02fe1.9o4 ferrite/peo nanocomposites is found to increase from 8.3298.349 å. the increase in (a) has been explained with respect to ionic radii of cations. the ionic radii of dopants such as of terbium (0.93 å) and dysprosium (0.912å) are larger than that of host cations; ferric ions (fe3+ is 0.64 å), (li+1 is 0.74 å) and (ni2+ is 0.69 å). the raise in lattice constant is owing to substitution of small-size ions with the larger ones (azhar khan et al., 2014; ishaque et al., 2010). figure 2: lattice constant and crystallite size of li0.5ni0.48tb0.02dy0.02fe1.9o4 ferrite/peo nanocomposites journal of materials and physical sciences 3(2), 2022 100 the average size of crystallite was deliberated by the scherer’s equation (soibam, phanjoubam, sharma, sarma, & prakash, 2009). initially the value of crystallite size of li0.5ni0.48tb0.02dy0.0.02fe1.9o4 ferrite/peo nanocomposites decreases and then it increases with an increase of ferrite concentration (al-hilli, li, & kassim, 2012). these variations are shown in table 2 as well as in fig. 2. 3.2. spectral analysis the ftir spectra of li0.5ni0.48tb0.02dy0.0.02fe1.9o4 ferrite/peo nanocomposites are measured in the range 500-4500 cm-1 and these are shown in fig. 3 (a-e). ftir bands detected in the range of 400-600 cm−1 are assigned to metal-oxygen stretching vibrations. the “absorption bands” which are in the given range 500-600 cm-1 are attributed as tetrahedral-sites (a) fundamental stretching vibration of metal-ions while the peaks appearing within 400-385 cm-1 are attributed as “octahedral sites (b) among the metal stretching vibrations” (choodamani et al., 2013). (a) (b) (c) (d) (e) figure 3: ftir spectra (a: li0.5ni0.48tb0.02fe1.90o4, b: li0.5ni0.48tb0.02fe1.90o4, c: li0.5ni0.48tb0.02fe1.90o4, d: li0.5ni0.48tb0.02fe1.90o4 e: li0.5ni0.48tb0.02fe2o4) muhammad ishfaq, mahvish gul, hatem alamri, gulfam nasar, faseeh ur raheem 101 both mention fundamental bands attributed to the vibrations of octahedral and tetrahedral sites of cations in the spinel ferrites lattice. the appeared variation in the absorption location of tetrahedral and octahedral complexes of spinel arrangement is attributed to the diverse detachment between ferric-oxygen ions (fe3+–o2−) in the tetrahedral and octahedral-sites (srivastava, ojha, chaubey, sharma, & pandey, 2010). the peaks appeared in the range 1500-1700 cm-1 are due to the n-h and c = o vibrations of stretching. the spectra appeared above 3600 cm-1 are due to moisturizing and water molecules (srivastava et al., 2014). table 1 the synthesized compositions of polymer, ferrite/polymer composites. sr. no. composition ferrite : polymer ratio 1 p polymer 2 fp1 0.1g : 1g 3 fp2 0.2g : 1g 4 fp3 0.3g : 1g 5 fp4 0.4g : 1g 6 fp5 0.5g : 1g table 2 lattice parameter and crystallite size of ferrite/polymer nanocomposites ferrite concentration (x) lattice constant (a) å crystallite size (d) nm 0.1 8.329 47.76 0.2 8.3316 36.56 0.3 8.342 34.70 0.4 8.348 39.57 0.5 8.349 47.24 3.3. morphological analysis the “scanning electron micrographs” (sem) is best for morphological analysis of li0.5ni0.48tb0.02dy0.0.02fe1.9o4 ferrite/peo nanocomposites are shown in fig. 4 (a-c). the micrographs of nanocomposites indicate irregular size of the particles. a slight agglomeration of particles has been observed owing to the inter particles (particle-particle) interactions. particles of ferrite are monitored for uniform encapsulation with polymeric matrix which signifies the presence of the nano-crystalline ferrites into the medium of polymer. all sem images exposed the confirmation of nano-sized structure in all compositions. an increase in the average crystallite size was observed with increasing ferrite content (patil, jadhav, & hankare, 2013; srivastava et al., 2010). (a) journal of materials and physical sciences 3(2), 2022 102 (b) (c) figure 4: sem micrograph of ferrite/peo nanocomposites (a: li0.5ni0.48tb0.02fe2o4 (fp 1), b: li0.5ni0.48tb0.02fe2o4 (fp-3), c: li0.5ni0.48tb0.02fe2o4 (fp-5)) 3.4. dielectric properties for li0.5ni0.48tb0.02dy0.0.02fe1.9o4 ferrite figure 5 and 6 demonstrate the frequency dependent difference of “dielectric constant (real component)” and “dielectric loss (imaginary component)” respectively of li0.5ni0.48tb0.02dy0.0.02fe1.9o4 ferrite/peo nanocomposites taken at ambient temperature within 1 mhz-3 ghz. it is evident from the figures that both “dielectric loss” and “dielectric constant” exhibit dispersion with frequency. both ɛ´ and ɛ" show increasing trend at lower frequency but decline quickly at larger frequency. this kind of behavior basically involves the spreading process due to “maxwell-wagner type interfacial polarization” which is in good agreement with two-layer “koop’s phenomenological model”. the electron exchange phenomenon happening between ferrous fe2+/ ferric fe3+ ions result in rearrangement of charges under the influence of an external applied electric field which is responsible for the electric polarization. the degree of polarization drops off with increasing the frequency and approaches a steady value because the variation of position of electrons between the two types of ferrous fe2+/ ferric fe3+ ions cannot match with the alternating field further than a certain frequency limit. the interfacial as well as dipolar polarization participate at low frequency while contribution to hopping process at high frequency mainly comes from the electronic polarization. muhammad ishfaq, mahvish gul, hatem alamri, gulfam nasar, faseeh ur raheem 103 figure 5: dielectric constant of li0.5ni0.48tb0.02fe1.90o4 ferrite/peo nanocomposites figure 6: dielectric loss of li0.5ni0.48tb0.02fe1.90o4 ferrite/peo nanocomposites several resonance peaks occurred at high frequency (f > 1.5 ghz) once the frequently electrons transfer between ferrous (fe2+) /ferric (fe3+) ions become equivalent to the frequency of external applied ac field which occurred due to un-damped dipoles. this type of phenomenon is termed as ferromagnetic resonance (azhar khan et al., 2014; singh, agarwal, & sanghi, 2011). generally, when an ion possesses two stable states e and f carrying some potential energies with them and separated through a potential barrier, then jumping probability on either side is the same for both ions. the frequency at which ions journal of materials and physical sciences 3(2), 2022 104 change their polarity at any side is named as its natural frequency. the moment at which external applied field and natural frequencies become equivalent, highest amount of electrical energy is transferred to oscillating ion that increases power loss which caused the resonance effect and ultimately the shaping the resonance peaks (asif iqbal et al., 2014). 3.4.1.loss tangent fig. 7 displays the “dielectric loss factor” variation with frequency from 1 mhz-3 ghz for all ferrite-polymer nanocomposites. it is obvious from fig. 7 that tanδ decreases with increasing the frequency. when the frequency of the externally applied ac electric field is much smaller as compared to the electrons hopping frequency between ferrous fe2+/ ferric fe3+ ions then electrons can chase the applied field and as a resultant, loss is maximum. when the frequency of the externally applied electric field is high than the hopping frequency of the electron exchange between fe3+-fe2+ ions, electrons cannot chase the applied field further than certain frequency limit resulting in a minimum loss. at lower frequency tanδ is high and tends to decrease quickly at larger frequency in agreement with koop’s phenomenological model. it is worth remembering that high energy loss is associated with small frequency region while this loss has low value for high frequency zone (asif iqbal et al., 2014). figure 7: tan loss of li0.5ni0.48tb0.02fe1.90o4 ferrite/peo nanocomposites figure 8 reveals the deviation in conductivity behavior for all samples of ferritepolymer nanocomposites. the ac conductivity plots indicate that all compositions follow a rising behavior at lesser frequency area whereas dispersion takes place at a greater frequency zone. the “two-layer of the ferrite composites comprise of well conducting grains, alienated from each other through a thin layer of resistive grain boundaries explained by koop’s and “maxwell-wagner model. both dielectric polarization and conduction procedure are coupled to each other. grains play dominant role at higher frequency and hopping rate between ferrous fe2+/ ferric fe3+ ions get increased owing to this phenomenon, therefore the ac electrical conductivity increased (asif iqbal et al., 2014). muhammad ishfaq, mahvish gul, hatem alamri, gulfam nasar, faseeh ur raheem 105 figure 8: ac conductivity of li0.5ni0.48tb0.02fe1.90o4 ferrite/peo nanocomposites conclusion li0.5ni0.48tb0.02dy0.10fe1.90o4 ferrite/polyethylene oxide nanocomposites were produced by chemical process. xrd spectra revealed that the produced peaks attributed to fcc spinel structure except at 33°. the size of crystallites was measured using “scherrer’s equation”. the calculated crystallites size lies in 34-47 nm range. ftir spectra show solid interactions between these ferrite nanoparticles and polymers. scanning electron microscopy revealed heterogeneous grain size distribution. the dielectric parameters were optimized by raising the amount of ferrite fraction of the composite materials. all the samples (fp1fp5) exhibit peaking behavior. these nanocomposites exhibit resonance phenomenon in the high frequency range (ghz). the “dielectric constant” reduces with raising the frequency in the nanocomposite samples. a peaking behavior is observed for all the samples at 1.6 ghz and 2.4 ghz. the rate of tangent loss also falls with increasing frequency. a resonance phenomenon in the frequency range 1.65-3 ghz is observed for fp1-fp5. the measurement of “dielectric constant” and “tangent loss” with frequency of the applied field and doping concentration of rare earth doped li-ni ferrite in polyethylene oxide suggest suitability of these ferrite-polymer-nanocomposites in high frequency applications. references abbas, s. m., dixit, a. k., chatterjee, r., & goel, t. c. 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(2014). cofe2o4-graphene nanocomposites synthesized through an ultrasonic method with enhanced performances as anode materials for li-ion batteries. nano-micro letters, 6(4). doi:10.1007/s40820-014-0003-7 http://dx.doi.org/10.1016/j.mseb.2010.06.005 http://dx.doi.org/10.1016/j.cap.2014.04.013 http://dx.doi.org/10.1016/j.jallcom.2012.05.119 https://doi.org/10.52131/jmps.2023.0401.0034 32 journal of materials and physical sciences volume 4, number 1, 2023, pages 32 45 journal homepage: https://journals.internationalrasd.org/index.php/jmps investigating nickel ferrite (nife2o4) nanoparticles for magnetic hyperthermia applications muhammad naqeeb ahmad1, hamid khan1, lubna islam2, m. hisham alnasir3, shahid nisar ahmad4, muhammad tauseef qureshi5*, muhamamd yaqoob khan1* 1 department of physics, kohat university of science and technology, 26000 kohat, khyber pakhtunkhwa, pakistan 2 department of pharmacy, university of malakand, chakdara, dir (lower), khyber pakhtunkhwa, pakistan 3 department of applied physics, federal urdu university of arts, science and technology, islamabad, pakistan 4 national center for physics,shahdara valley road,45320 islamabad, pakistan 5 department of basic sciences, college of preparatory year, university of hail, hail, saudi arabia article info abstract article history: received: april 07, 2023 revised: may 18, 2023 accepted: may 23, 2023 available online: june 29, 2023 many new promising therapeutic and diagnostic methods in medical science use magnetic nanoparticles (mnps). drug targeting, tumor detection, and magnetic hyperthermia treatment are the most common fields of interest where already clinical trials are being performed. nickel ferrite (nife2o4) nanoparticles have received much attention for their potential applications in such fields. a series of samples of nickel ferrite (nife2o4) nanoparticles have been synthesized using a co-precipitation route at different annealing temperatures ranging from 150 ℃ to 1000 ℃ and labeling them as s1, s2, s3, s4, and s5. the average particle size obtained from xrd data is found to lie in the range of 15 – 55 nm. the crystal structure of the prepared nife2o4 four samples annealed at different temperatures is fcc with a lattice constant of 8.34 å, which agrees with the values. the magnetic properties of the samples were investigated from temperature-dependent hysteresis loops using vibrating sample magnetometer (vsm). the saturation magnetization (coercivity) is found to increase (decrease) with particle size. the hyperthermia measurements are performed by applying alternating magnetic fields of various amplitudes (oe) and frequencies (khz). the measured heating ability of the prepared nanoparticles is obtained from the so-called specific absorption rate (sar), which is found to increase with increasing frequency and field amplitudes. using the experimentally obtained sar value, we also used matlab code to model the heat diffusion equation to get information on the temperature rise within the tumor as a function of tumor radius and treatment time.the sample s4 annealed at a temperature of 900 ℃ is found to be the most suitable candidate for hyperthermia applications at the frequency of 543 khz because of its capability to produce heat in the therapeutic range of 42-48 ℃ and with an sar value of 500 w/g. keywords: nickel ferrite xrd vsm specific absorption rate hyperthermia applications © 2023 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding authors’ email: yaqoob@kust.edu.pk, m.qureshi@uoh.edu.sa 1. introduction cancer is the leading cause of death worldwide. surgery, radiation therapy, and chemotherapyare the most commonly used procedures to treat cancer. however, the efficacy of these procedures is limited, and each one has its side effects(hussain et al., 2021). https://journals.internationalrasd.org/index.php/jmps mailto:yaqoob@kust.edu.pk mailto:m.qureshi@uoh.edu.sa m. naqeeb ahmad, hamid khan, lubna islam, m. hisham alnasir, shahid nisar ahmad, m. tauseef qureshi, m. yaqoob khan 33 hippocrates proposed hyperthermia or thermotherapy and stated that all skin tumors on the outer surface of the body may be treated with hot iron (tomitaka & takemura, 2019). hyperthermia was used for the first time, and a swedish gynecologist westermarck used hyperthermia in 1898to treat cervical cancer by running hot water through an intracavity spiral tube (westermark, 1898). hyperthermia is acknowledged as a distinct therapy used alone or as an adjuvant to chemotherapy or radiotherapy (bañobrelópez, teijeiro, & rivas, 2013; kumar & mohammad, 2011). the biochemical processes occurring in the cell, such as metastasis, are vulnerable to alteration in temperature. a few centigrade temperature rises in body temperature, i.e., from 37 ℃ (42 to 48) ℃, is required to kill the cancer cell (dennis et al., 2008). furthermore, the temperature range 42 ℃ 48 ℃ can either be used as an adjuvant therapy or can directly kill the cancer cells by a process called thermoabalation, a function of time and temperature (hildebrandt et al., 2002). tumor cells have poor heat dissipation and constrained blood flow due to their abnormal growth and disorganized atomic structure. therefore, cancerous cells are highly sensitive to temperature than healthy cells (cihoric et al., 2015; kakehi et al., 1990; kuwano et al., 1995). in combination with radiotherapy and chemotherapy, hyperthermia has shown 39% to 85% of complete response rate (kuwano et al., 1995). however, hyperthermia has side effects, such as temperature control within the tumor and non-localized heating, thereby damaging the healthy cells. moreover, secondary harmful effects have been found with normal tissues when hyperthermia was combined with other treatment modalities (bañobre-lópez et al., 2013). to overcome the problems associated with hyperthermia, an alternative approach, known as magnetic hyperthermia, was used to treat cancer. magnetic hyperthermia has been found to be a promising technique for treating cancerusing magnetic nanoparticles(singh, 1990; szasz, szigeti, szasz, & benyo, 2018).when magnetic nanoparticles are subjected to rf fields, heat is generated through various loss mechanisms, such as hysteresis and relaxationallosses. hysteresis losses occur in multidomain particles, whereas relaxation losses occur in single-domain superparamagneticnanoparticles (spmnps). ideally, the nanoparticles used for magnetic hyperthermia should be superparamagnetic. when spmnps are exposed to radiofrequency fields, their magnetic moments rotate in the direction of the field and then relax back to the original field orientation called néel relaxation. brownian relaxation is due to the rotation of the particle within a viscous fluid where heat is produced due to friction at the surface particles(kalambur, han, hammer, shield, & bischof, 2005). superparamagnetic or ferromagnetic nanoparticles, i.e., fe3o4 /ᵧ fe2o3, have been extensively investigatedin magnetichyperthermia to treat cancer. recent challenges in magnetic hyperthermia are high heat efficiency and controlled in vivo temperature in the therapeutic limit of 42 – 48 °c(pradhan, giri, banerjee, bellare, & bahadur, 2007). the heating efficiency of probed nanoparticles is determined by measuring the specific absorption rate (sar) as given by equation (1). 𝑆𝐴𝑅 = 𝐶. ( 𝑑𝑇 𝑑𝑡 ) 𝑡=0 . 𝑚𝑠𝑎𝑚𝑝𝑙𝑒 𝑚𝑚𝑎𝑔. (1) where 𝑚 is the mass of the sample, 𝐶 is the specific heat capacity of the sample, and 𝑚𝑚𝑎𝑔 is the mass fraction of the magnetic component. the value of sar determines the dose of the nanoparticles; the higher the sar value, the low dose will be required to treat cancer, thereby reducing the side effects. nickel ferrite (nife2o4) is a soft spinel ferrite (šepelák et al., 2007). nickel ferrite (nife2o4) has been found to be the alternative to fe3o4 /ᵧ fe2o3 due to its biocompatibility and heating efficiency (bae, lee, & takemura, 2006; menelaou, georgoula, simeonidis, & dendrinou-samara, 2014; stefanou et al., 2014). in this work, we have synthesized nickel ferrite (nife2o4) from nickel and iron nitrate salts using the chemical co-precipitation route. the prepared samples were further calcined/annealed at different temperatures to vary the particle size and crystallinity. the structural, magnetic, and hyperthermia measurements were carried out to find the suitability of nickel ferrite (nife2o4) for magnetic hyperthermia applications. journal of materials and physical sciences4(1), 2023 34 2. experimental details the nife2o4 sample was prepared using a chemical co–precipitation route. the details of the synthesis procedureare given in the work carried out to synthesize tin oxide nanoparticlesby tazikeh, s. et al.(tazikeh, akbari, talebi, & talebi, 2014).the chemical precursors used for the synthesis of nife2o4 were nickel nitrate hexahydrate (ni (no2)3.6h2o) and iron nitrate nonahydrate (fe (no3)3.9h2o). the aqueous solution was prepared by mixingiron nitrate and nickel nitrate in the de-ionized water. thensodium hydroxide (naoh) was added slowlywhile continuously stirring to set the ph value at 10– 11. the solution was heatedat 100 ºc for one hour and then washed with ethanol to remove excess sodium and nitrate traces. the precipitates formed were left to dry at 50 ºc overnight. the obtained sample was labeleds1. the resultant sample was ground and calcined at various temperatures, i.e., 600 ºc, 800 ºc, 900 ºc, and 1000 ºc each for ten hours and was labeled as s2, s3, s4, and s5, respectively. xrd wasused to obtain structural parameters such as crystallite size and lattice parameters.a scanning electron microscope (sem)with a magnification power of up to 1,000,000 x and a resolving power of 10 åwas used to study the surface morphology of the samples. magnetic properties in the temperature range of 100 k to 300 kwere carried out by vibrating sample magnetometer (vsm). the heating efficiency was investigated by using an rf-induction unit.finally, a simple model based on a heat diffusion equation is used (in matlab) to see the temperature rise as a function of the time of treatment and tumor radius. 3. results and discussion 3.1. structural characterization 3.1.1. xrd analysis the phase identification of the product was carried out by powder x-ray diffraction (xrd, bruker d8-advance, germany). the xrd patterns were collected by steps of 0.02 in the 20 – 80 degree range with a constant counting time of 0.6 s per step at room temperature. the phase formation and purity were examined by powder x-ray diffraction using cu-ka (λ = 1.5425 å) radiation. the xrd graph explains features of synthesized nanoparticles of nife2o4, especially the effect of annealing on phase contribution and change/increase in crystallize size. figure 1: xrd intensity as a function of diffracted angle for different samples of nife2o4 nanoparticles annealed at different temperatures m. naqeeb ahmad, hamid khan, lubna islam, m. hisham alnasir, shahid nisar ahmad, m. tauseef qureshi, m. yaqoob khan 35 the xrd pattern of the prepared nanoparticles of nife2o4 is shown in fig. 1. almost a similar data trend can be seen in these figures as reported in the literature. seven major peaks can be observed, which correspond to the crystal planes (220), (311), (222), (400), (422), (511), and (440) with the face centered cubic (fcc) spinel structure of nife2o4with fe cations at tetrahedral sites and nickel cations at octahedral sites. bragg's reflections are found to be sharp and intense and have been indexed, confirming the formation of cubic spinel structure in a single phase. the average crystal size is determined by the debye-scherrer equation 𝑡 = 𝐾𝜆 𝛽𝑐𝑜𝑠𝜃 (2) where λ is the x-ray wavelength (cu kα radiation and equals to 0.154 nm), θ is the bragg diffraction angle (in radians), and β is the fwhm (full-width half maximum) or integral breadth of the xrd peak appearing at the diffraction angles θ. t is the thickness of crystallite, and k is constant dependent on the crystalline shape. the crystalline size is found at the maximum intensity peak of the plane (311) to be 15, 30, 40, and 55 nm for s2, s3, s4, and s5 samples annealed at different temperatures, respectively. annealed samples have more intensepeaks than prepared ones. it indicates more crystallinity of the nickel ferrite. the effect of increasing temperature on the improvement of the crystallinity of nickel ferrite and the conversion of some nickel and iron oxides to produce nickel ferrite crystallites can be seen in the same figure. the crystallization of nickel ferrite improves at increasing the annealing temperature. all the reflections are indexed based on the standard index system. the broad peaks of the xrd patterns stipulate that the particles of the synthesized samples are in the nanometer range. the presence of hematite diffraction peaks contributes as an impurity and reveals the formation of a multi-phase. s5 does not show the presence of a hematite phase. still, the diffused reflectance spectra (drs) show an extra line of band gap energy (as shown below in fig.6). it may be due to the effects of fluoresces, and the phase contribution of hematite is thus ignorable. all four samples' calculated cubic lattice parameters are the same (8.34 å)as thatfor the standard nife2o4 (8.34 å). structural parameters are given in table 1. table 1 lattice constants and average crystallite size obtained from xrd data for different samples of nife2o4 structural parameter s2 s3 s4 s5 lattice constant (a=b=c) (å) 8.332 8.334 8.342 8.343 the average crystallite size (nm) 15 30 40 55 3.1.2. sem analysis the scanning electron microscope (sem) images of samples s3, s4, and s5 are shown in fig. 2. the images depict mass agglomerations of tiny particles resulting in large particles. he images show dense aggregation because of high surface energies and tend to grow into larger accumulation. 3.2. magnetic measurements the magnetic behavior of nife2o4 nanoparticles was investigated using vibrating sample magnetometry (vsm) (lakeshore vsm 7410) with an applied field of 10 koe or 1 tesla.the magnetic measurements, i.e.,magnetization as a function of the fieldfor the two samples s4, s5 taken attemperatures in the range of 150 k to 300 k, are shown in fig. 3. the hysteresis loops of the samples s4 and s5 at 300 k have been compared in fig. 3 (a). journal of materials and physical sciences4(1), 2023 36 figure 2: the sem images of samples s3, s4, and s5 -1000 -500 0 500 1000 -80 -60 -40 -20 0 20 40 60 80 -100 -50 0 50 100 -10 -5 0 5 10 m a g n e ti z a ti o n ( e m u /g ) magnetic field (mt) s4 s5 @ 300 k (a) -1000 -500 0 500 1000 -80 -60 -40 -20 0 20 40 60 80 -100 -50 0 50 100 -10 -5 0 5 10 m a g n e ti z a ti o n ( e m u /g )) magnetic field (mt)) 150 k 300 k s4 (b) figure 3: magnetic hysteresis loopsfor (a) s4 and s5 at 300 kand (b) s4 at two different temperatures, i.e., 150 k and 300 k the magnetic properties of the materials, such as magnetization and coercivity, strongly depend on the particle size, shape, crystallinity, etc.the samples show ferromagnetic behavior. the temperature and the size of the mnps significantly influence the magnetic properties, as depicted in fig. 3 and table 2.it can be observed from fig. 3(a) that s5 has a larger magnetization than s4 because magnetization increases with increasing particle size. the samples' saturation magnetization (ms) as a function of temperature is plotted in fig. 4. it can be seen that ms decreases with the rise in temperature for both samples. this can be attributed to the thermal effects dominating at high temperatures. however, sample s5 due to its large particle size has relatively large magnetization at all temperatures compared to sample s4. the magnetic parameters determined from these plots have been listed in table 2. table 2 crystallite size, saturation magnetization, coercivity, and retentivity of nife2o4 at 300 k sample calcination temperature t (ºc) crystallite size d (nm) saturation magnetization ms (emu/g) coercivity hc (mt) retentivity mr (emu/g) s4 900 40 47.62 50.01 13.55 s5 1000 55 61.65 35.17 20.22 m. naqeeb ahmad, hamid khan, lubna islam, m. hisham alnasir, shahid nisar ahmad, m. tauseef qureshi, m. yaqoob khan 37 150 200 250 300 50 55 60 65 m a g n e ti z a ti o n ( e m u /g )) temperature (k) s4 s5 (a) 150 200 250 300 35 40 45 50 55 60 65 c o e rc iv it y ( m t ) temperature (k) s4 s5 (b) figure 4: (a) magnetizationand (b) coercivity as a function of temperature for two samples, s4 and s5, annealed at 900 ºc and 1000 ºc, respectively the inset of fig. 3(a) shows the coercivity of the samples. the coercivity of s4 is larger than s5, likely due to the transition of the particle size from single domain to multidomainas the particle size increases. however, the product of coercivity and magnetization (zeeman energy) for s4 is comparable to that of s5, suggesting that sample s4 might have the same heating ability as sample s5. this is because the heating ability of the sample in an rf field depends upon both the magnetization and coercivity(anisotropy). table 3 the coercivity of samples at different temperatures sample coercivity (mt) 150 k 200 k 250 k 300 k s3 (50 mg) 43.31 39.97 38.94 33.85 s4 (30 mg) 61.85 57.62 52.29 50.01 s5 (50 mg) 42.65 40.46 36.64 35.17 the coercivitiesofthe samples s4 and s5 from their m(h) loops taken at various temperatures have been plottedin fig. 5. the decrease in coercivity can be observed with increasing temperature. the decrease in coercivity may be due to the effects of thermal fluctuations of the blocked moment across the anisotropy barrier. coercivity is strongly dependent on particle size as well. if we correlate coercivity with particle size, it can be inferred that it (coercivity) directly relates to particle size it decreases as the size of particles increases. further, the coercivity of s4 is greater than that of s3 and s5 due to the small mass(30 mg) of s4 than that of s3 and s5 (50 mg).coercivity values as a function of temperature are given in table 3 below. 3.3. hyperthermia measurements magnetically induced heating measurements were carried out on 50 mg powder for the samples s4 and s5 under an alternating field strength and frequency of230 ôeand 543 khz, 200 ôe, and 172 khz, respectively. the results are shown in fig. 5. it can be seen that heating is produced in both the samples at the applied fields and frequencies. the heating produced by magnetic nanoparticles depends on parameters such as particle size, saturation magnetization, effective anisotropy, applied field strength, and frequency. the effect of field strength and frequency can be observedin fig. 5. the rapid increase in temperature can be observed (fig. 5(a) compared to fig. 5(b)) with the increase in frequency. sample s5 has a large heating potential compared to sample s4 due to its relatively large saturation magnetization. the heating produced is usually quantified by measuring the specific absorption rate (sar), the power released per unit mass by mnps in heat. maximizing the sar is an essential objective in magnetothermal therapy in order to reduce the dosage of the magnetic nanoparticles. journal of materials and physical sciences4(1), 2023 38 figure 5: (a, b) heating efficiency of s4 & s5 samples at 543 khz and 172 khz at external fields 23mt and 20mt, respectively we measured the specific absorption rate (sar) using equation (2). the initial slope values ( 𝑑𝑇 𝑑𝑡 ) 𝑡=0 were extracted from their heating curves in fig. 5.the obtained sar values are listed in table 4.thevalues of sar obtained are 500 w/g and 450 w/g at 543 khz for the samples s5 and s4, respectively.in addition, it can also be seen that sample s4 produces heat in the therapeutic range of 42 – 48 ℃ at 543 khz since the cancer cells are more sensitive to this temperature range as compared to the healthy cells. hence, sample s4 is found to be most suitable at the given frequency of 543 khz for magnetic hyperthermia application. table 4 specific absorption rate (sar) of s4 & s5 comparison of s5 at two fields and frequencies samples sar (w/g) 230 oe 200 oe 172 khz 543 khz s4 400 450 s5 480 500 3.4. drs analysis diffuse reflectance spectroscopy (drs) technique was used to study band gaps from the light absorption spectrum. the band gap of nife2o4 nanoparticles was determined by using tauc, davis, and mott relation given by: (ℎ𝜈𝛼) 1 𝑛 = 𝐴 (ℎ𝜈 − 𝐸𝑔 ) (3) where 𝛼 is the absorption coefficient, 𝜈is the light frequency,𝑎𝑛𝑑 𝐴 is a proportionality constant,𝐸𝑔is the band gap energy. band gap energy can determine from the plot(hνα)1/nas a function of energy (hν), as shown in fig. 6, by extrapolating the straight line to the axis intercept. there are two values of the energy gap, as evident from fig. 6 for s2 – s5. the second band gap is due to the presence of hematite. the presence of the hematite phase is already confirmed from xrd data. the sample s6 is not annealed separately from other samples it is collected after tga/dta analysis which is made at 1200℃. in this sample, no other band gap energy line can be seen as only nife2o4 is present, and the hematite phase is absent. the value of the indirect band gap of energy for nife2o4 is found to be around 1.53 ev, and for hematite, it is in the range of 1.82 1.96 ev. m. naqeeb ahmad, hamid khan, lubna islam, m. hisham alnasir, shahid nisar ahmad, m. tauseef qureshi, m. yaqoob khan 39 figure 6: extraction of energy gap value for nife2o4 from the tauc-plot for different samples (s1 s6) annealed at 150 ºc (s1), 600 ºc (s2), 800 ºc (s3), 900 ºc (s4), 1000 ºc (s5) and at 1200 ºc (s6) each for ten hours 3.5. thermal analysis thermal studies of nanoparticles include the determination of their decomposition and crystallization temperature. for this, thermogravimetric and differential thermal analysis (tg-dta) techniques were used in which dried precursors of nife2o4 were obtained via the co-precipitation method using a thermal analyzer (mettler toledo star system). the tg-dta curve in fig. 7 shows that major weight loss occurs from 270 ºc to 420 ºc. the plateau formed from 450 ºc to 1200 ºc indicates the formation of nife2o4 crystallites already confirmed by xrd. figure 7: tga/dta curve of nife2o4 nanoparticles dried at 100 ºc 3.6. modeling approach and mathematical modelling an analytical approach was adopted to meet the heat propagation problem produced by magnetic nanoparticles (nife2o4) within. the thermal properties of human lung tissue obtained from literature were used,and the value of heat produced by the mnps was used from our experimental data. assumptions journal of materials and physical sciences4(1), 2023 40 some assumptions in our model, such as the spherical shape of the tumor and linear decrease in particle concentration from the center to the periphery of the tumor, are made. this linear particle concentration correlation is also applied to power density. according to the assumed initial conditions, the temperature of the tumor and healthy tissues, as well as that of the boundary/interface between healthy and tumorous tissue (r = r), is assumed to be the same nearly equal to body temperature (to= 37 ℃). the heat diffusion equation is used to model thedistribution of heat behavior governed by the mnps due to the application of alternating magnetic field and is given by: 𝜌𝑐 𝜕𝑇 𝜕𝑡 = 𝜅 1 𝑟2 𝜕 𝜕𝑟 (𝑟2 𝜕𝑇 𝜕𝑟 ) + 𝑤𝑟 (4) where t(r, t) is the temperature at a discrete point in the tissue, which continuously varies with time; 𝑤𝑟 = 𝑃 is the power density, 𝜅is the thermal conductivity; c is the specific heat capacity, and ρ is the density of a lung’s tumor. the boundary conditions are given by: 𝑇(0,0) = 𝑇0 at equilibrium temperature at the origin/center of the tumor, 𝑇(𝑟, 0) = 𝑇0 at the interface between the tumor and surroundings 𝑇(𝑟, 𝑡) = 𝑇 at any arbitrary value of r and t. for simplification to solve the equation, we transform 𝑇 into a new variable φ, i.e., 𝛷(𝑟, 𝑡) = 𝑟∆𝑇where∆𝑇 = 𝑇(𝑟, 𝑡) − 𝑇0 (5) differentiating this concerning 't’; 1 𝑟 𝜕𝛷(𝑟,𝑡) 𝜕𝑡 = 𝜕𝑇(𝑟,𝑡) 𝜕𝑡 (6) and concerning 'r’; 𝑟 𝜕2𝛷(𝑟,𝑡) 𝜕𝑟2 = 𝜕 𝜕𝑟 (𝑟2 𝜕𝑇(𝑟,𝑡) 𝜕𝑟 ) (7) now substituting equationseqs. (6) & (7) into eq. (1) we arrive at: 1 𝐷 𝜕𝛷 𝜕𝑡 = 𝜕2𝛷(𝑟,𝑡) 𝜕𝑟2 + 𝑤 𝜅 𝑟2 (8) where 𝐷 = 𝜅 𝑐𝑝 is the thermal diffusivity of the tumor. the boundary conditions also need to be transformed in terms of 𝛷.at 𝑟 = 0, by assuming the finiteness of temperature at the interface: 𝛷(0, 𝑡) = 𝑟 (𝑇(0, 𝑡) − 𝑇0) = 0 𝛷(𝑅, 𝑡) = 𝑅(𝑇(𝑅, 𝑡) − 𝑇0) = 0 𝛷(𝑟, 0) = 𝑟(𝑇(𝑟, 0) − 𝑇0) = 0 𝛷(𝑟, 𝑡) = 𝑟(𝑇(𝑟, 𝑡) − 𝑇0) = 0 due to the homogeneity of boundary conditions, the source term allows us to break the solution to the equation into the homogenous and steady-state equation. by putting t = 0, the solution to steady state equation (8) becomes: 𝛷𝑠 = −𝑤𝑟4 12𝜅 + 𝑐1𝑟 + 𝑐2 (9) by applying the steady state b.cs, as stated above, one can get the values of the constants c1 and c2and put in eq. (9) to get: 𝛷𝑠 (𝑟, 𝑡) = 𝑤𝑟(𝑅3−𝑟3) 12𝜅 (10) the same b is needed to get a solution for a homogeneous equation. cs will be applied by neglecting source term, i.e., 𝑤 𝜆 𝑟2, equation (8) becomes: m. naqeeb ahmad, hamid khan, lubna islam, m. hisham alnasir, shahid nisar ahmad, m. tauseef qureshi, m. yaqoob khan 41 1 𝐷 𝜕𝛷ℎ 𝜕𝑡 = 𝜕2𝛷ℎ 𝜕𝑟2 (11) with b.cs 𝛷ℎ (0, 𝑡) = 𝑟 (𝑇(0, 𝑡) − 𝑇0) = 0 𝛷ℎ (𝑅, 𝑡) = 𝑅(𝑇(𝑅, 𝑡) − 𝑇0) = 0 𝛷ℎ (𝑟, 0) = 𝑤𝑟(𝑅3−𝑟3) 12𝜅 (i) for the solution of eq. (11), we use the separation of variables: let 𝛷ℎ (𝑟, 𝑡) = 𝑅(𝑟) 𝑇(𝑡) (12) on differentiating the above equation concerning 'r’ & ‘t’, we arrive at 𝑅"(𝑟) + 𝑅(𝑟)𝜆 = 0, 𝑇′(𝑡) + 𝐷𝑇(𝑡)𝜆 = 0, where 𝜆 = 𝑅"(𝑟) 𝑅(𝑟) = 1 𝐷 𝑇′(𝑡) 𝑇(𝑡) 𝑅"(𝑟) + 𝜆𝑅(𝑟) = 0 (13) and 𝑇′(𝑡) + 𝐷𝜆𝑇(𝑡) = 0 (14) applying b.cs 𝛷ℎ (0, 𝑡) = 𝑅(0) 𝑇(𝑡) = 0 𝛷ℎ (𝑅, 𝑡) = 𝑅(𝑟) 𝑇(𝑡) = 0 to above equations (9), we arrive at the solutions, i.e., 𝑅(𝑟) = 𝑐𝑠𝑖𝑛 ( 𝑛𝜋𝑟 𝑅 ) (15) with 𝑅(0) = 𝑅(𝑟) = 0 for 𝑇(𝑡) ≠ 0. similarly, solving for eq. (14) we get 𝑇(𝑡) = 𝐴𝑒 −𝐷( 𝑛𝜋𝑟 𝑅 ) 2 𝑡 (16) putting back these eqs.(15) & (16) in eq. (12), and after simplification, we get: 𝛷ℎ (𝑟, 𝑡) = ∑ 𝐴𝑛𝑠𝑖𝑛 (𝑛𝜋𝑟/𝑅)𝑒 −𝐷(𝑛𝜋/𝑅)2𝑡 ∞ 𝑛=1 (ii) on comparing both the homogenous state eqs. (i) and (ii), we arrive at: − 𝑤𝑟(𝑅3−𝑟3) 12𝜅 = ∑ 𝐴𝑛𝑠𝑖𝑛 (𝑛𝜋𝑟/𝑅)𝑒 −𝐷(𝑛𝜋/𝑅)2𝑡∞ 𝑛=1 (17) where is a constant 𝐴𝑛 = 2 𝑅 ∫ 𝐹(𝑥)𝑠𝑖𝑛(𝑛𝜋𝑟/𝑅)𝑑𝑟 and 𝐹(𝑥) = − 𝑤𝑟(𝑅3−𝑟 3) 12𝜅 . substituting the value of f(x) and integrating eq. (17) by parts, we get: 𝐴𝑛 = −𝑤𝑅2 6𝜅 ∫ 𝑟𝑠𝑖𝑛 ( 𝑛𝜋𝑟 𝑅 ) 𝑑𝑟 𝑅 0 + 𝑤 6𝑅𝜅 ∫ 𝑟4𝑠𝑖𝑛 ( 𝑛𝜋𝑟 𝑅 ) 𝑑𝑟 𝑅 0 (18) 𝐼1 = −𝑤𝑅2 6𝜅 ∫ 𝑟𝑠𝑖𝑛 ( 𝑛𝜋𝑟 𝑅 ) 𝑑𝑟 𝑅 0 and 𝐼2 = 𝑤 6𝑅𝜅 ∫ 𝑟4 𝑅 0 𝑠𝑖𝑛 ( 𝑛𝜋𝑟 𝑅 ) 𝑑𝑟. after simple integration, we arrive at the solutions, i.e. 𝐼1 = 𝑤𝑅4 6𝜅 (−1)𝑛 𝑛𝜋 and 𝐼2 = 𝑤 6𝑅𝜅 [ −𝑅5(−1)𝑛 𝑛𝜋 − 12𝑅5(−1)𝑛 (𝑛𝜋)3 + 24𝑅5(−1)𝑛 (𝑛𝜋)5 {(−1)𝑛 − 1}]. by putting values of𝐼1 and 𝐼2 in eq. (18) to get the value of𝐴𝑛: 𝐴𝑛 = 2𝑤𝑅4 𝜅 (−1)𝑛 (𝑛𝜋)3 [1 + 2 (𝑛𝜋)2 {(−1)𝑛 − 1]} (19) now put back the value ofan into eq. (ii) we get i1 i2 journal of materials and physical sciences4(1), 2023 42 𝛷ℎ (𝑟, 𝑡) = ∑ 2𝑤𝑅4 𝜅 (−1)𝑛 (𝑛𝜋)3 [1 + 2 (𝑛𝜋)2 {(−1)𝑛 − 1}]𝑠𝑖𝑛 ( 𝑛𝜋𝑟 𝑅 ) 𝑒 −𝐷( 𝑛𝜋 𝑅 ) 2 𝑡∞ 𝑛=1 (20) the final solution for 𝛷(𝑟, 𝑡) can be obtained by combining thesteady state solution and the homogeneous solution in the form, 𝛷(𝑟, 𝑡) = 𝛷𝑠 (𝑟, 𝑡) + 𝛷ℎ (𝑟, 𝑡) 𝛷(𝑟, 𝑡) = 𝑤𝑟(𝑅3−𝑟3) 12𝜅 + ∑ 2𝑤𝑅4(−1)𝑛 (𝑛𝜋)3 [1 + 2 (𝑛𝜋)2 {(−1)𝑛 − 1}]∞𝑛=1 𝑠𝑖𝑛𝑐 ( 𝑛𝜋𝑟 𝑅 ) (21) 𝑒 −𝐷( 𝑛𝜋 𝑅 ) 2 𝑡 on reverse transformation, 𝛷t 𝛷(𝑟, 𝑡) = 𝑟(𝑇(𝑟, 𝑡) − 𝑇0) we arrive at our final solution: (22) as time endures, the temperature of the whole tumor will reach the steady state where we can measure the final temperature of the tumor the steady state temperature. the effect of heat diffusion within the tumor and in the surrounding healthy tissues can also be investigated by modeling more realistic assumptions in the model. temperature across the tumor will almost reach steady as time collapses. at this point, we can measure the final temperature of the tumor (denoted by ts). from that steady state temperature and original temperature (to) of the tumor, we can determine the thermal conductivity of the tumor by using the relationship deduced from the solution (18) as given below in eq. (23). this can be further used to stimulate the more realistic heat diffusion from the tumor to nearby surrounding tissues in an advanced model. when the temperature of the tumor reaches to steady state. i.e., at r = 0. eq. (22) becomes: 𝑇𝑠 = 𝑇𝑜 + 𝑤𝑅3 12𝜅 (23) table 5 thermal conductivity, specific heat capacity, density, and thermal diffusivity of healthy and tumorous lung tissue (giering, lamprecht, minet, & handke, 1995) material 𝜿 (w m-1 k-1) c (j g-1 k-1) ρ (kg m-3) d (m2.s-1) lung tissue 0.11 4.2 161 1.62*10-7 tumorous lung tissue 0.552 4.17 998 1.32*10-7 where the parameters, such as thermal conductivity (𝜅), specific heat capacity (c), density (ρ), and thermal diffusivity (d) of healthy and tumorous lung tissue, are taken from the literature (giering et al., 1995). from fig. 8, one can see the temperature dependence on the radius of the human lung tumor. this figure shows that temperature is nearly constant for almost 1 cm of the radius. then it starts decreasing onward and drops off to human body temperature at the peripheries, i.e., 4 cm. this is because of the imposed conditions over the problem. it is pertinent to mention that the temperature is obtained in the therapeutic range (42 – 48 oc) for cancer treatment of lung tumors. without imposing such conditions on the problem, heat would have been propagated out of the tumor. this figure does not show a realistic situation. to combat the realistic situation, one cantackle this problem with advanced modeling techniques, for instance, with an approach using the finite difference method. 𝑇(𝑟, 𝑡) = 𝑇0 + 𝑤(𝑅3−𝑟3) 12𝜅 + ∑ 2𝑤𝑅3(−1)𝑛 (𝑛𝜋)3 [1 + 2 (𝑛𝜋)2 {(−1)𝑛 − 1}]∞𝑛=1 𝑠𝑖𝑛𝑐 ( 𝑛𝜋𝑟 𝑅 ) 𝑒 −𝐷( 𝑛𝜋 𝑅 ) 2 𝑡 m. naqeeb ahmad, hamid khan, lubna islam, m. hisham alnasir, shahid nisar ahmad, m. tauseef qureshi, m. yaqoob khan 43 figure 8: temperature as a function of the radius of the tumor. every individual line represents a specific time point figure 9 shows the temperature produced by the prepared nanoparticles, i.e., nife2o4, as a function of the radius of the human lung's tissue and time to get the maximum temperature in the therapeutic range. here, we see that temperature increases as time passes and reaches its maximum value (52.5 ℃) and then starts decreasing from the center to the peripheries of the lung's tumor with the assumed radius size of 4 cm. figure 9: temperature as a function of time and distance from the center of the tumor obtained from the analytical solution of the problem conclusions the nife2o4 mnps with crystallite sizes in the 15 – 55 nm range were prepared via the co-precipitation route. the samples showed ferromagnetic behavior, and a decrease in saturation magnetization with the temperature rise was observed for samples s4 and s5.however, sample s5 was found to have large saturation magnetization at all temperatures compared to the sample s4. the coercivity of sample s4 was larger than that of s5; however, the coercivity and magnetization (zeeman energy) for both samples are nearly the same, suggestingalmost the same heating capabilities for these samples. from hyperthermia measurements, sample s4 was found to be the most suitable candidate for hyperthermia applications at 543 khz because of its ability to produce heat in the therapeutic range of 42 – 48 ℃ and having a highsar value. we found from the heat journal of materials and physical sciences4(1), 2023 44 diffusion equation modeling that temperature reaches a maximum constant value of 52.5 ℃ within 2 minutes and then drops when moving towards the lung's tumor peripheries. although the modeling results are not that realistic in the current study, they can be made realistic in a more advanced and suitable modeling using the same heat diffusion equation from the perspective of hyperthermia treatment of cancer. reference bae, s., lee, s. w., & takemura, y. 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(1898). uber die behandlung des ulcerirenden cervix carcinoma mittels knonstanter warme. zentralbl gynkol, 1335-1339. https://doi.org/10.52131/jmps.2022.0302.0027 59 journal of materials and physical sciences volume 3, number 2, 2022, pages 59 70 journal homepage: https://journals.internationalrasd.org/index.php/jmps investigation of dielectric, magnetic and electrical behavior of bfo/gnps nano-composites synthesized via sol-gel method arsa nageena1, alina manzoor1*, amir muhammad afzal2, muhammad imran arshad1, aamir shahzad1, muhammad kashif1 1 department of physics, government college university, faisalabad,38000, pakistan 2 department of physics, riphah international university, 13-km raiwind road, lahore-54000 pakistan article info abstract article history: received: august 08, 2022 revised: september 13, 2022 accepted: december 29, 2022 available online: december 31, 2022 nano composites of ba0.5bi0.5nd0.05fe0.95o3 multiferroic with graphene nano platelets (gnps)x (x = 0, 0.125 %, 0.375 %, and 0.5 %) were synthesized using sol-gel auto ignition process. xrd analysis revealed a single rhombohedral distorted phase of ba0.5bi0.5nd0.05fe0.95o3. the present study shows the impact of gnps on the structural, electrical, dielectric, and magnetic properties of ba0.5bi0.5nd0.05fe0.95o3 multiferroics. the substitution of rare earth elements in pure bfo reduced the value of leakage current which is the basic drawback related with pure bfo. the prepared nanocomposites are then sintered at 800 °c for 7 hrs. the xray diffraction patterns showed the rhombohedral distorted perovskite crystal structure of the prepared samples including lattice constant, crystallite size, and x-ray density. the average crystallite sizes of the prepared nanocomposites are noticed in the range 28.14 -to 29.74 nm with increasing the gnps concentration and lattice constant is found in the range 11.59 -to 11.61 å. temperature-dependent resistivity is first observed to increase with an increase in temperature then resistivity decreased with increasing the temperature which indicates a semi-conductor-like behavior as measured by two probe i-v characteristics. lcr technique showed that both the dielectric constant and the dissipation factor are decreased with an increase in frequency. vsm results indicated that saturation magnetization is noted to increase while remanent magnetization decreases with increasing concentration of gnps. keywords: multiferroics bifeo3 xrd dielectric magnetization resistivity © 2022 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: alinamanzoor@hotmail.com 1. introduction in multiferroic materials (bfo,) ferroelectricity and ferromagnetism coexist. in multiferroic (bifeo3) properties, electric and magnetic moderate to each other. multiferroic materials are commonly studied due to wide range of spintronic device, sensor microelectronics device and information storage device.(alina manzoor et al., 2016; a manzoor et al., 2015) the crystal structure of bismuth multiferroic (bfo) is perovskite structure belongs to r3c space group with general formula abo3(sobhan et al., 2015). where a is a higher cation than b cation and o is oxygen. the main advantage of perovskite materials contains easy and simple fabrication, large solar adsorption, high flexibility of carriers for cell designs, less or low non-radiative charge carrier recombination and capitalization of dyesensitive photovoltaic cells(green, ho-baillie, & snaith, 2014). due to its multiferroic https://journals.internationalrasd.org/index.php/jmps mailto:alinamanzoor@hotmail.com journal of materials and physical sciences 3(2), 2022 60 characteristics, bismuth ferrite (commonly known as bifeo3) has proven to be one of the most attractive perovskites. bismuth ferrites bifeo3 are rhombohedral perovskites that belong to the r3c space group. bismuth ferrites exhibit both ferromagnetic and ferroelectric properties at the same time. these structures have lattice parameters ar = 5.63ao, ar = 59.35 is a typical multiferroic, in which antiferromagnetic and ferroelectric exist simultaneously(fatima, ali, iqbal, & rizwan, 2017). very important example bfo of a room temperature is a multiferroic materials with high range of neel temperature tn ~ 640 k and ferroelectric ordering with a curie temperature tc ~ 1103 k (a manzoor et al., 2015; tian et al., 2021). bismuth ferrite is one of the most effective visible light-driven photo catalysts. electrons move towards conduction bands when exposed to visible light, leaving holes in the valance band, which causes organic pollutants to degrade through oxidation and reduction processes. in perovskites structure the band gap can be changed by several methods for catalytic applications. specifically, the band-gap in bismuth ferrites can be changed by doping with transition metals or (rare-earth elements) fabricating its composite structures with additional other materials such as graphene. inside bfo co-substitution of iron and bismuth has been reported various times with increase magnetic, electric and photocatalytic properties. according to published research, rare-earth metal doping inside bfo significantly enhanced its physical and chemical properties(kiani et al., 2019; reetu, agarwal, sanghi, & ashima, 2011; umar et al., 2019). graphene is the two-dimensional crystalline form of carbon. graphene contains a single layer of carbon atoms with remarkable properties, such as chemical and thermal stability, high electron mobility, excellent electrical conductivity, and large surface area(akhavan, 2010). a high surface area is presented by single-layer of graphene. however it is exceedingly high cost and challenging to produce commercially. for environmental applications, graphene has exhibited good potential. graphene and bismuth ferrites (bifeo3) combination creates an e-trapping medium that effectively separates electron-hole charge carriers, reduces recombination rates, and increases photocatalytic activity (an et al., 2013; rostamnia, doustkhah, karimi, amini, & luque, 2015). due to the high cost and difficulty of producing pristine graphene, graphene nanoplatelets (gnp), a cost-effective multilayer graphene product, has recently emerged as a strong option for several applications, including dye-sensitized supercapacitors solar cells, and others. graphene nanoplatelets (gnps), are consist of multilayers of graphene in a range of 10 to 30 layers or more and a low-cost commercial product available in the form of flakes plates or particles. the gnps are less susceptible to defects because of their nanometerthickness. excellent characteristics of gnps include a efficient surface-to-volume ratio, low resistance, and strong mechanical qualities. depending upon these characteristics the (gnps) are very efficient materials usesd in photocatalysis, sensing, drug delivery, and optoelectronics device. the majority of carbon-based bifeo3 composites used in photocatalytic processes are mainly depends on reduced graphene oxide or graphene. mukherjee et al.(mukherjee, chakrabarty, kumari, su, & basu, 2018) prepared bifeo3, along with reduced graphene oxide, is used for photocatalysis and water splitting. bifeo3 can be synthesized using a wide range of techniques, including the solid-state method, wet chemistry method, co-operation method, hydrothermal method, etc. although the solid-state approach of synthesizing bifeo3 results in the pure phase of bifeo3 crystallites, there is typically poor uniformity and particle size control because of the high sintering temperature during the synthesis. wet chemical approaches, including sol-gel and hydrothermal procedures, are therefore preferable because they produce higher homogeneity and allow for better control of particle size and purity of samples (lam et al., 2021; nkwachukwu & arotiba, 2021; remya et al., 2020). to enhance certain of its features, bifeo3 can be substituted with rare earth metal ion (ma, li, & song, 2020; waghmare et al., 2018; zhang et al., 2012) and by adding graphene to prepare its composites to modify its dielectric and magnetic properties. 2. experimental procedure in preparation of ba0.5bi0.5nd0.05fe0.95o3 multiferroic the following metal nitrates including barium nitrate (ba(no3)2), bismuth chloride (bicl3), neodymium nitrate nanohydrate (nd(no3)3.h2o), iron nitrate (fe(no3)3.9h2o), citric acid (c6h8o7), and graphene nano-plates (gnps)were used . for the preparation of the solution, deionized/ arsa nageena, alina manzoor, amir muhammad afzal, m. imran arshad, aamir shahzad, muhammad kashif 61 distilled water was used. gnps doped bifeo3 (ba0.5bi0.5nd0.05fe0.95o3) with four samples of doping using different compositions like (x = 0, 0.125 %, 0.375 % and 0.5 %) were synthesized by sol-gel route. bismuth nitrate, barium chloride, neodymium nitrate nanohydrate, iron nitrate, citric acid and gnps were dissolved into distilled water in beakers and then mixed in a specific measured quantity of distilled water in a 500ml sized beaker for further process. obtained solutions of the samples were stirred with the help of a magnetic stirrer and for the sake of maintaining the ph of the samples at 7, the solution of ammonia was added drop after drop into the solution. different samples took different times for the conversion of a solution to be aqueous. variation of time was in between 3 to 4 hours, and after further heat treatment for 25 minutes the solution was converted into xero-gel, and ashes were seen in the beaker. finally, after some time our required powder of nanocomposites was obtained. for mixing all the materials properly and to make the powder finer, this obtained powder of multiferroic was grinded for 30 minutes with the help of a mortar and pestle. after grinding, samples were managed in a furnace for the sintering process at 800°c for 7 hours. sintering was done for condensing the materials. regrinding was done for 40 minutes by using a mortar and pestle after sintering to make the fine powder of samples. the product was packed for further characterization. to identify the required phase formation and crystal structure of the synthesized samples were identify by xrd diffractometer at room temperature in 20o -70o range. to determine the energy bandgap of under investigated samples uv-visible spectroscopy is employed. to confirm the dielectric response of materials in 1khz-1mhz frequency range was observed with impedance analyzer. the m-h loops and magnetic properties of gnps and nd substituted bismuth ferrites were understand by vsm analysis. the electrical properties of bfo/(gnps)x nanocomposites were study by using two probe iv measurements technique. 3. results and discussion 3.1. xrd study figure 1 shows the xrd patterns of the ba0.5bi0.5nd0.05fe0.95o3/(gnps)x ferrites with gnps concentration (x = 0, 0.125 %, 0.375 %, and 0.5 %) synthesized by the sol-gel method. figure 1 demonstrated the xrd patterns of gnps and nd substituted the bismuth ferrites that confirmes the rhombohedral perovskite structure belongs to space group (r3c). it can be seen that typical peaks of multiferroic with six predominate peaks occurred at 2θ = 21.01o, 27.44o, 31.74o, 42.07o, 45.49o and 56.49o across miller indices or plane (012), (002), (104), (202), (024) and (300) respectively. these peaks indicate the development of the crystal structure. along with the development of rhombohedral structures, also some traces of secondary phases were shaped. as can be seen, only a diffraction peak can be found in gnp pattern and is ascribed to the (002) plane. from the graph it is clear that when gnps concentration rises the intensity of a some trends weak and becomes vanished (rezlescu & rezlescu, 1974). it is observed that there is no splitting of peaks. as concluded from the graph the most intense peak is (104), and the angle 2θ of the most intense peak is observed to be 31.74°. average particle size of bifeo3 is observed by the use of well known scherrer equation(bharati et al., 2020; ishaque et al., 2016). d = k λ/ β cos θ (1) in above relation ß, d, λ, and k represent the wavelength of the x-ray, average crystallite size, peak broadening factor, and shape factors. it is observed that the value of ‘d’ enhanced by increasing the doping of gnps. the cell volume and lattice constant (c and a) are calculated by using the equation. v = a2c × sin60o (2) 1 𝑑2 = 4 3 [ℎ2 + ℎ𝑘 + 𝑘2 ] 𝑎2 + 𝑙2 𝑐2 (3) where h,k,l show the millan indices. the “a” and “c” exhibit an upward-downward trend as substitution is increased. the x-ray density is calculated using the following equation. journal of materials and physical sciences 3(2), 2022 62 ρx = 8𝑀 𝑉𝑐𝑒𝑙𝑙𝑁𝐴 (4) 20 30 40 50 60 70 in te n s it y (a .u ) 2 theta (degree) x=0.5% x=0.375% x=0.125% x=0 (0 1 2 ) (0 0 2 ) (1 0 4 ) (0 2 4 ) (3 0 0 ) (2 0 2 ) figure 1: xrd patterns of bfo/gnpx nano composites (x=0.0, 0.125%, 0.375%, 0.5%) table 1 crystallite size, x-ray density, lattice constant (a and c), and unit cell volume of ba0.5bi0.5nd0.05fe0.95o3 /(gnps)x nano composites (gnps)x (x) angle 2θ (degree) miller indices ( hkl ) crystallite size d (nm) x-ray density (g/cm3) lattice constant a (å) unit cell volume v (å)3 0 31.76o (104) 36.19 7.06 5.63 376.62 0.125 % 31.73o (104) 33.90 7.03 5.63 378.54 0.375 % 31.74o (104) 34.97 7.02 5.634 378.97 0.5 % 31.74o (104) 34.97 7.03 5.627 377.99 here vcell, m and na symbolizes the unit cell volume, molecular weight and avogadro’s number. some other parameters like x-ray density, vcell of bismuth ferrites (bfo) having hexagonal structure, bulk density, etc based on each composition are calculated and are listed below in table 1. with increasing the doping of gnps the value of x-ray density decreases in 7.02-7.06 g/cm3 range and the value of vcell increases 377.99376.62 (å)3.. scherer's formula is also used to determine the crystallite size (patterson, 1939). the crystallite size is determined to be between 33.9036.19nm. which is significantly smaller than other reports on substituted ferrites nanoparticles. which have been reported to be between ~70 nm (ahmadvand et al., 2010), 40-65 nm, and 36-58 nm. to obtain a suitable signal-to-noise ratio crystallite size play an important role in electronic devices and to achieve a good signal-to-noise ratio, crystallites must be less than 50 nm. the crystallite size in the present investigation is less than 50 nm, indicating that the synthesized materials may find use in the production of recording media devices to achieve the desired signal-to-noise ratio (sultan et al., 2014). 3.2. dielectric properties the room-temperature variation of dielectric constant (έ) and tangent loss (δ) for gnps doped bfo nanocomposites for a frequency range of 4 hz to 8 mhz are show in figures 2 & 3. the amount of electrostatic energy retained per unit volume per unit gradient is calculated by the dielectric constant. through the substance of dielectric constant arsa nageena, alina manzoor, amir muhammad afzal, m. imran arshad, aamir shahzad, muhammad kashif 63 measured the speed of relative speed of electromagnetic signal which move in the substance. dielectric constant was calculated using formula as; ε′ = 𝐶𝑝 𝐶𝑜 , co = 𝐴𝜖𝑜 𝑑 (5) where a is the area of pallet, cp is parallel capacitance, έ is dielectric constant, d is thickness of pallet and ϵo is permittivity respectively. figure 2 depicts the variation of dielectric constant (έ) as a function of applied field frequency. at the low frequency the dielectric constant exhibit the highest value which is due to impurities, moisture and dislocations. at high values of frequency, the values of the dielectric constant are so small that they become almost independent of the frequency. 0.0 2.0x10 6 4.0x10 6 6.0x10 6 8.0x10 6 0.0 2.0x10 -6 4.0x10 -6 6.0x10 -6 8.0x10 -6 d ie le c tr ic c o n s ta n t frequency(hz) x=0% x=0.125% x=0.375% x=0.5% figure 2: frequency vs permittivity of bfo/(gnps)x nanocomposites as the frequency increases the values of the dielectric constant become almost constant. in the starting low-frequency, range dielectric constant have higher values are explain on the basis of the space charge polarization due to in homogeneous present in dielectric structure (kumar & yadav, 2011). the dielectric constant follows the applied frequency in the low region frequency region up to 1 mhz after that graph merge each other and shows the independent behavior up to 8 mhz for all compositions. the highest value of dielectric constant is obtained at x = 0.375 % as compared to all other samples. it is concluded that the contribution of electrons to measure the dielectric parameters is independent of applied field frequency (dai, chen, li, xue, & chen, 2013). on both sides, when ions equally the applied frequency and natural frequency of field becomes almost equal, power loss rises and resonance peak take place (khan et al., 2016). ba0.5bi0.5nd0.05fe0.95o3/(gnps)x composites consist of conducting grains separated by high resistive grain boundaries understood by koop’s theory and maxwell-wagner model of dielectrics (ali, islam, awan, & ahmad, 2013; dilshad et al., 2016; shaikh et al., 2021). dielectric tangent loss is given by: tanδ = 1 2𝜋𝑓𝐶𝑝𝑅𝑝 (6) journal of materials and physical sciences 3(2), 2022 64 cp is parallel capacitance, f is frequency and rp is the parallel resistance, respectively. baviour of tangent loss for ba0.5bi0.5nd0.05fe0.95o3/(gnps)x composites with respect to frequency at room temperature is shown in figure 3. 0.0 2.0x10 6 4.0x10 6 6.0x10 6 8.0x10 6 0 1x10 1 2x10 1 ( ta n l o s s ) frequency (hz) x=0% x=0.125% x=0.375% x=0.5% figure 3: frequency vs tangent loss of bfo/(gnps)x nanocomposites figure 3 depicts the variation of dielectric loss of bfo/(gnps)x nanocomposites follow the applied frequency. in the low frequency region dielectric loss decreases due to the involvement of grains. at high frequency region of 2mhz-8 mhz the dielectric loss exhibit frequency independent behavior because the dipoles are aligned in the direction of applied frequency. from the graph it is clear that the maximum value of tangent loss is observed for x= 0.375 % sample as compared to all other samples. the loss are strongly dependent on some other important factors including oxygen vacancies, interfacial polarization and predomenently on applied frequency. (chen, j. et al., (2013). dielecric dispersion in ferrites is based on koop’s phenomenological theory and maxwell-wagner's model. tangent loss in ferrites is considered to be creating from two phenomena: charged defect dipoles and hopping of electrons. 3.3. impedance spectroscopy standard impedance spectroscopy was used to investigate the electrical properties of the samples and was carefully examined in terms of interfacial/electrode, grain, grain boundary, etc. impedance technique was used to record electrical responses at particular temperatures when a sinusoidal signal with a frequency of 1 khz to 8 mhz was applied (brahma et al., 2022). the change in the impedance with respect to the frequency is shown in the figure. as the frequency increase, the measured value of impedance decreases. with the increasing frequency values, the impedance decreases, and at a point, the value of impedance almost becomes constant and seems to be independent of the frequency due to the space charge polarization caused by the accumulation/increase of carriers, including polarons, vacancies, and defects in the ceramics energetic by the high frequency, which leads to the maximum conductivity (priyadarsini jena, mohanty, parida, parida, & nayak, 2020). for concentration x=0.375 % there is constant with increasing frequency. arsa nageena, alina manzoor, amir muhammad afzal, m. imran arshad, aamir shahzad, muhammad kashif 65 0.0 2.0x10 6 4.0x10 6 6.0x10 6 8.0x10 6 0.0 2.0x10 6 4.0x10 6 6.0x10 6 8.0x10 6 1.0x10 7 im p e d a n c e frequency(hz) x=0% x=0.125% x=0.375% x=0.5% figure 4: frequency vs impedance of bfo/(gnps)x nanocomposites 3.4. electrical resistivity the log resistivity (𝜌) versus 1000/t, also called arrhenius plots are shown in figure 5. current-voltage(i-v) measurements are taken to measure the conducting capacity of the prepared photocatalysts. with the application of applied voltage (− 4.5 v to +4.5 v) the response of current was calculated. hydraulic press was utilized to make a pellet of definite dimensions. the conductivity and resistivity of all prepared sample were calculated by using this formula: 𝜌 = 𝑅𝐴 ℎ (7) 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 0 1 2 3 4 5 6 7 8 9 lo g o f re s is ti v it y (o h m -c m ) 1000/t(k) x=0 x=0.125 % x=0.375 % x=0.5 % figure 5: arrhenius plots of bfo/(gnps)x nanocomposites journal of materials and physical sciences 3(2), 2022 66 where 𝜌, r, a, and h represented resistivity, resistance, area of pallet and thickness of the pallet, respectively. the resistance is calculated using ohms law (v = ir). in this research work, it is excluded that in the material the log resistivity is decreased and then decreased which manipulates the conductor and semiconductor behavior. in the start at the lower temperature values, the fabricated material showed the behavior of conductor but as the temperature increased the value of resistivity decreased which showed the semiconductor behavior of the fabricated material. so, in this research work, it is observed that the bfo/(gnps)x nanocomposites have both conductor and semiconductor behavior at the prescribed compositions and this behavior totally depends on the temperature. by changing the temperature, the behavior of the fabricated material also changed. i–v graphs for all under investigated photocatalyst materials are shown in fig. 5. the calculated values of electrical conductivity (σ) for all bifeo3, gd-doped bifeo3, and gd-doped bifeo3/rgo nanocomposite were 3.61 × 10− 14 s/cm, 3.02 × 10− 13 s/cm, and 0.12 × 10− 9 s/cm, respectively. 3.5. uv-visible spectroscopy analysis uv-visible spectroscopy is used for the study of optical properties of bfo/(gnps)x as shown in figure 6. figure 6 has shown the optical absorbance of bfo/(gnps)x nanocomposites in the range of 200-800 nm. initially, optical absorption is high and after that with increasing the concentrartion of wavelength, it decreased. it is observed that variation in peak such as absorbance varies with the variation of wavelength. to calculate the band gap (eg), the given below relation is used: 𝛼ℎ𝜈 = 𝐴(ℎ𝜈 − 𝐸𝑔) 𝑛 (8) 200 300 400 500 600 700 800 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 a b so rb an ce (a .u ) wavelength(nm) x=0 x=0.125% x=0.375% x=0.5% figure 6: absorbance vs wavelength of bfo/(gnps)x nanocomposites here α, hv, a, n, and eg are absorption coefficient, photon energy, integer, and band gap energy respectively. the eg is calculated using n for allowed direction transition. the calculated values of eg from experimental data are 2.71 ev, 2.79 ev, 2.85 ev, and 2.88 ev for samples (gnps)0, (gnps)0.125%, (gnps)0.375%, and (gnps)0.5%, respectively as shown in figure 7. in this experiment it is note that band gap continuously increases and turned toward lies in visible region with increasing the concentration of gnps. this variation in band gap is directly depend on gnps concentration and phenomenon is mainly due to the hybridization between cfo and gnps nanostructures. this increase in hybridization between cfo and gnps is due to the strong fe–o–c bonds. the additional energy levels that are introduced by this chemical interaction between the composite material's conduction and valence bands, band gap energy is reduced (devi & srinivas, 2017). conversely, it is observed that, increase the concentration of gnps band gap increase. this difference for higher doping of gnps was mainly by burstein-moss effect. by the application of this effect arsa nageena, alina manzoor, amir muhammad afzal, m. imran arshad, aamir shahzad, muhammad kashif 67 in semiconductor materials the conduction band is full of electrons. so maximum number of electrons enter in conduction band from the grapheme. as a result higher concentration of gnps provide more π-electrons to transfer the conduction band of cfo nanostructures(israr et al., 2020). 1 2 3 4 5 6 7 0 100000 200000 300000 400000 500000 b a n d g a p (a lp h a h v ) energy (ev) x=0 x=0.125% x=0.375% x=0.5%2.71ev 2.79ev 2.85ev 2.88ev figure 7: energy vs bandgap of bfo/(gnps)x nanocomposites 3.6. magnetic analysis the magnetic behavior of gnps doped ba0.5bi0.5nd0.05fe0.95o3 nanocomposites is investigated using vibrating sample magnetometer at room temperature. the m-h loops of all prepared nanocomposites are shown in figure 8. the magnetic parameters of the synthesized samples, such as remanence (mr), saturation magnetization (ms), and coercivity (hc) are determined from m h loops and are listed in table 2. due to the high value of leakage current and coercivity all the m-h loops are broken and unsaturated (ahmed et al., 2022). so, to produce m-h loops for bfo, the higher applied voltage is not favorable as under observation samples are damaged under high temperatures. as can be seen from table 2, the saturation magnetization is decreased from 35.95 -to 27.18 emu/g and the value of remanence magnetization (mr) is increased from 6.59 -to 11.27 emu/g up to substitution level x=0 to 0.125 % of gnps. after this, the value of ms is increased from 27.18 -to 36.89 emu/g whereas the remanent magnetization is decreased from substitutional level x= 0.125 % to 0.5 % with an increase in the gnps concentration. with gnps doping, the highest value of saturation magnetization is 36.89 emu/g for substitution level x=0.5 % and highest value of remanent magnetization is 11.27 emu/g for x= 0.125 %. the coercivity first decreases from 168.75 to 130.43 oe for x= 0 to 0.125 % then it increases suddenly with an increase in the concentration of gnps. the nano composites of bi0.5ba0.5nd0.05fe0.95o3 and gnps have a significant impact on their magnetic properties. table 2 magnetic parameters such as saturation magnetization (ms), remanence magnetization (mr), coercivity (hc) and ratio 𝑴𝒓 𝑴𝒔 from hysteresis loops of bfo/(gnps)x nanocomposites concentrations (gnps)x ms (emu/g) mr (emu/g) hc (oe) remanent ratio (emu/g) r= mr/ms 0 35.95 6.59 168.75 0.18 0.125 % 27.18 11.27 130.43 0.41 0.375 % 29.48 3.75 149.99 0.13 0.5 % 36.89 3.64 160.27 0.098 journal of materials and physical sciences 3(2), 2022 68 -6000 -4000 -2000 0 2000 4000 6000 -6000 -4000 -2000 0 2000 4000 6000 -40 -30 -20 -10 0 10 20 30 40 -40 -30 -20 -10 0 10 20 30 40 0 0 -10 0 10 -10 0 10 m ( e m u /g ) h (oe) x=0 x=0.125% x=0.375% x=0.5% m ( e m u /g ) h (oe) x=0 x=0.125% x=0.375% x=0.5% figure 8: combined mh loops of bfo/(gnps)x nanocomposites conclusion gnps doped bfo multiferroics were successfully prepared by selfignited auto combustion sol-gel method. xrd patterns showed that bfo/gnps nano composites possessed a rhombohedral distorted perovskite structure. crystallite size was found below 50 nm while lattice constant was noted in the range of 5.62-5.63 å. dielectric constant and dissipation factor were observed to decrease with an increase in frequency. electrical properties revealed the semiconductor type behavior of bfo/gnps nano composites. uvvisible spectroscopy analysis showed that band gap rises with higher gnps ratio due to burstein-moss effect would permit more π-electrons to enter the conduction band. the saturation magnetization increased while remnant magnetization decreased with increasing concentration of gnps. the importance of iron is well-known, and it is being employed in various engineering applications due to superior mechanical properties, appropriate corrosion resistance at a wide range of ph, and availability at a cheaper cost(mcneill & edwards, 2001; nishikata, ichihara, hayashi, & tsuru, 1997). although the use of pure iron is limited due to stability issues because some applications demand extended stability and lesser density to strength ratio. therefore, iron has been replaced by other materials like aluminum, magnesium, stainless steel, and other alloys in various fields of applications. but this material is still being used in many applications and the material scientists have always been working to counter its associated problems and to improve its properties for various 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(2012). influence of la doping on magnetic and optical properties of bismuth ferrite nanofibers. journal of nanomaterials, 2012. https://doi.org/10.52131/jmps.2021.0202.0019 88 journal of materials and physical sciences volume 2, number 2, 2021, pages 88 94 journal homepage: https://journals.internationalrasd.org/index.php/jmps studies of molecular dynamics and electronic structure in cubic-sic by using density functional tight binding approach r.m.a. khalil1*, fayyaz hussain1, niaz ahmad niaz1 1 department of physics, bahauddin zakariya university, 60800, multan, pakistan article info abstract article history: received: october 01, 2021 revised: november 30, 2021 accepted: december 30, 2021 available online: december 31, 2021 the radiation damage in silicon-carbide and its result are presented in this research. the density functional tight binding (dftb) approach is used to perform molecular dynamics simulations to implement the dftb+ code (elstner et al., 1998). this methodology shows the making and breaking of chemical bonding as well as describes the realistic total energy for the larger systems. repulsive potentials have been developed to prevent the atoms to stay close to each other during the model of high energy collisions also correctly describe the configurations during the atomic separation within the typical range. the extent and nature of damages are characterized within the collision event up to 10kev. the band structure of sic has been studied using minimal basis (sp) as applied in dftb+. the value of band gap shows that cubic sic is a large band gap semiconductor material. this value is comparable with the given in literature. density of states is also calculated by using the tight binding approach. the peaks of spectrum have been compared with the experimental values found in literature. keywords: density functional tight binding minimal basis repulsive potential density of states band gap radiation damage © 2021 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: muhammadarif@bzu.edu.pk 1. introduction silicon carbide is a well-known material in semiconductor technology. it is used as a nuclear fuel for fusion reactors. the aim of current research is to study the radiation damage and electronic structure in sic by using the density functional tight binding approach. the density functional tight binding scheme is more accurate than empirical tight binding methods. the basic structural unit in sic consists of four si (or c) atoms are connected by the covalent bond with a c (or si) atom at the centre. sic is mostly used in electronic devices due to its strong chemical bonding, physical stability, and other attractive electrical, optical, and thermal properties. detailed knowledge of electronic structure is essential to explain the applications of this material (käckell, wenzien, & bechstedt, 1994). tight binding models are very successful to the study both semiconductor and metallic systems especially in systems which are too large to study via ab initio techniques. despite the successes of tb models, tb approach has some limitations one of these is the treatment of compound or multi-elemental systems (mercer, 1996). gao et al investigated the long-range migration of points defects in cubic sic by using atomic-scale simulations for molecular dynamics. they calculated the activation energy of migration barrier for c and si interstitials and this energy was compared with the experimental results. they also compared the energy barrier for c interstitial and vacancy diffusion with ab intio data (gao, weber, posselt, & belko, 2004). rauls et al has used the self-consistent-charge density functional-based tight binding theory to investigate the migration of vacancies at high temperatures along with the entropy contribution to gibbs free energy. they found the energy barrier for sub lattice migration of vsi is lower than that for vc whereas vsi should anneal out at low temperature, which was consistent with experimental results for as grown sic (rauls, frauenheim, gali, & deák, 2003). bernstein et https://journals.internationalrasd.org/index.php/jmps mailto:muhammadarif@bzu.edu.pk r.m.a.khalil, fayyaz hussain, niaz ahmad niaz 89 al used naval research laboratory nonorthogonal tight binding method to present the electronic structure and total energy calculations for sic. they compared the energies of different structures of silicon carbide. they described the elastic constant and vacancy formation energies for the cubic structure by using sp tight binding model and showed the good agreement of theoretical and experimental results (bernstein, gotsis, papaconstantopoulos, & mehl, 2005). mahmood et al used the density functional and total energy pseudopotential technique under the generalized gradient approximation to study the electronic structure in zinc-blende sic. they compared their results about energy gap theoretically and experimentally. they also calculated the density of state, charge density and bulk modulus of cubic silicon carbide (mahmood & sansoresa, 2002). demkov et al used an ab initio method to determine the microscopic atomic structure of si-c alloys. they determined the effect of ordering using the plane wave calculation on the ordered structures. they found two different types of si-c bonds. the first type of bond was the si-c bond of the length near 1.86 å as in bulk and the second type of bond was about 1.65 å for a carbon atom in a near-planar sp2 configuration with its si neighbours (demkov & sankey, 1993). salvador et al showed that tight binding approach is a quite effective description of inter-atomic bonding especially dealing with covalent bond of materials.they described the physics of point defects on the basis of making and breaking of bond and discussed the defects energetics in β-sic by using tight binding model (salvador, perlado, mattoni, bernardini, & colombo, 2004). 2. density functional tight binding theory the modern tight binding approach has an origin in the slater and koster’s important paper (slater & koster, 1954). the concept of linear combination of atomic orbitals (lcao) has been used to develop the rapid, robust, generally transferable and accurate methods for the calculation of atomic and electronic structure, energies and forces of large and complex systems. in order to use the dft practically, the kohn-sham orbitals ψ𝑖 (𝑟) are required to expand some way. majority of basis set expansion of the kohn-sham orbital ψ𝑖 can be expanded in term of suitable basis functions 𝜒𝜇 (𝑟) ψ𝑖 (𝑟) = ∑ 𝐶𝜇𝑖𝜇=𝑖 𝜒𝜇 (𝑟) (1) the eigen states of a system were expended using standard tight binding methods to represent the exact many-body hamiltonian operator in terms of an orthogonalized basis of the atomic like orbitals. lcao ansatz leads to secular equation in the form: ∑ 𝑐𝜇𝜈 𝑀 𝜈 (𝐻𝜇𝜈 0 − 𝜖𝑖 𝑆𝜇𝜈 ) = 0, ∀𝜇, 𝑖, (2) total energy expression of the system can be written as the sum of band structure energies and repulsive energies (frauenheim et al., 2000). 𝐸 = 𝐸𝑏𝑠 + 𝐸𝑟𝑒𝑝 (3) the dft total energy is transformed into tb form including the charges fluctuation (porezag, frauenheim, köhler, seifert, & kaschner, 1995) 𝐸2 𝑇𝐵 =  occ i ⟨ψ𝑖 | oĥ |ψi⟩ + 1 2  n  , 𝛾𝛼𝛽 ∆𝑞𝛼 ∆𝑞𝛽 + 𝐸𝑟𝑒𝑝 (4) by applying the variational principle to energy functional eq.4,kohn-sham equation transformed in to set a algebraic equations and modified hamiltonian matrix elements can be written as (porezag et al., 1995): 𝐻𝜇𝜈 = ⟨𝜙𝜇| oĥ |𝜙𝜈⟩ + 1 2 𝑆𝜇𝜈 ∑ (𝛾𝛼𝜉 𝑁 𝜉 + 𝛾𝛽𝜉 )∆𝑞𝜉 = 𝐻𝜇𝜈 𝑜 + 𝐻𝜇𝜈 1 ; ∀ 𝜇 ∈ 𝛼, 𝜈 ∈ 𝛽 (5) journal of materials and physical sciences 2(2), 2021 90 an analytic expression for the inter atomic forces for the use in molecular dynamics simulations can be derived by taking the derivative of the expression of eq.4 with respect to nuclear coordinates. 𝐹𝛼 = − occ i i n   𝑐𝜇𝑖 𝑐𝜈𝑖 ( 𝜕𝐻𝜇𝜈 𝑜 𝜕𝑅𝛼 − (𝜖𝑖 − 𝐻𝜇𝜈 1 𝑆𝜇𝜈 ) 𝜕𝑆𝜇𝜈 𝜕𝑅𝛼 ) − ∆𝑞𝛼  n  𝜕𝛾𝛼𝜉 𝜕𝑅𝛼 ∆𝑞𝜉 − 𝜕𝐸𝑟𝑒𝑝 𝜕𝑅𝛼 (6) 3. results and discussion neighbours in 64 atoms supercell got too close to each other on bombarding the high radiation up to 10kev as shown in figure 1. repulsive potentials was developed to avoid atoms un-physically get too closed by using self consistent density functional-based tight binding (scc-dftb) approach as shown in figure 2. exponential part of repulsive potentials were smoothly joined with spline part of repulsive at the inter atomic distance r=1.0 a.u. (atomic unit). the parameterization set pbc-0-3 was used to develop the repulsive (köhler & frauenheim, 2006; köhler, hajnal, deák, frauenheim, & suhai, 2001; rauls, elsner, gutierrez, & frauenheim, 1999). figure 1: neighbouring si and c atoms are getting too close (0.2å) in 64 atoms of sic supercell figure 2: repulsive vs. inter atomic distance by using the parameterization set pbc-0-3 angle between c-si-c atoms found from 109.50 to 1300 during stretching. bond length of si-c of the value 2.32 å was found before breaking as shown in figure 3. jmol software was used to visualize the dynamics of atoms. carbon atoms were shown by black small balls and silicon atoms are indicated by light gray balls. figure 4 describes the correct description of dftb modelling for making and breaking of bond in large super cell of silicon carbide. time step of the value 0.01 fs was choosen corresponding to energy of radiation 2kev. initial value of high energy was dispersed with the change in crystalline to amorphous phase as shown in figure 5. r.m.a.khalil, fayyaz hussain, niaz ahmad niaz 91 figure 3: the bond angle between c-si-c at the maximum streching of si-c bonds figure 4: variation of force with time using scc-dftb during cascaded process, energy was shifted between first neighbours due to stretching and compressing the bond. oscillatory behavior in distance between neighbours indicates the compressing and stretching of bond. as the intial value of bombarding energy was greater than si-c bond energy caused the neighbouts reached too close near the boundary of cell.the nearest calculated distance between si-c atoms was found at value of 0.2 å. at this point, hamiltonian matrix was failed to diagonalized at this postion.this point is marked by gray arrows in figure 6. table 1 values of physical quantities calculated by scc-dftb for cubic sic 𝒂(å) v(a.u.)3 etotal(h) p(a.u.) 5.0334 861 -11.7241 -0.0013 4.7937 743 -11.8613 -0.0010 4.5654 642 -11.9400 -0.0005 4.3480 555 -11.9471 0.0007 4.1306 476 -11.7953 0.0031 3.9240 408 -11.4765 0.0066 3.7278 350 -10.9640 0.0115 3.5414 300 -10.2169 0.0192 3.3643 257 -09.1592 0.0315 figure 5: the dispersing of initial 2kev in 64 atoms supercell of sic after 1000 steps at time step 0.1fs journal of materials and physical sciences 2(2), 2021 92 figure 6: the change in distance between the nearest neighbour si-c atom total energy etotal in the units of hartree (h) reaches the minimum value at the stable lattice constant 𝑎 = 4.3480 å as given in table 1 and experimental value of lattice constant is found 𝑎 =4.343 å (rauls et al., 2003). calculated values of pressure p increase with decrease in volume v of the system below the stable lattice constant 𝑎 and become negative on increasing the volume v of the system. figure 7: band structure of sic calculated by dftb+ along l𝐆𝐚𝐦𝐦𝐚-x line using the parameterization set pbc-0-3 band structure of sic has calculated along the high symmetry lgamma-x directions in face centred cubic brillouin zone (bz). in scc-dftb approach, the minimal basis (sp) leads to value of direct band gap 4.81ev at center of bz as shown in figure 7. the calculated value of band gap is high as compared with experimental value 2.39ev (park, cheong, lee, & chang, 1994; rauls et al., 2003). this shows that cubic sic is a large band gap material. first two bands in conduction band degenerates and splits as move toward the l-point and xpoints. density of states in arbitrary units are also calculated by using scc-dftb method. peaks in valence band found at the values of energy-4.94ev,-6.23ev,-8.04ev,-12.01ev,14.96ev,-16.25ev as shown in figure 8.these values of peaks are comparable with experimental values of peaks at -3.0ev,-5.0ev,-8.5evand -12.8ev in a valence band respectively as mentioned by karch et al (karch, pavone, windl, strauch, & bechstedt, 1995). conduction band has also three prominent peaks at the values of 1.60ev,2.73ev, 4.33ev respectively. the largest peak of density of states lies at 1.60ev in conduction band as shown in figure 8. r.m.a.khalil, fayyaz hussain, niaz ahmad niaz 93 figure 8: density of states for sic calculated by dftb+ using the parameterization set pbc-0-3 4. conclusion dftb approach is useful to study molecular dynamics of the radiation damage up to 10kev collision energy for large cubic sic systems. at the minimum value of distance between nearest neighbours, molecular dynamics kinetic energy of the system is greater than pair potential energy. this is main reason of atoms getting too close. this problem was corrected by developing new repulsive potentials between nearest neighbours (si-c atoms). dftb approach also overestimates the value of band gap in cubic sic system. references bernstein, n., gotsis, h., papaconstantopoulos, d., & mehl, m. 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(2003). theoretical study of vacancy diffusion and vacancy-assisted clustering of antisites in sic. physical review b, 68(15), 155208. salvador, m., perlado, j., mattoni, a., bernardini, f., & colombo, l. (2004). defect energetics of β-sic using a new tight-binding molecular dynamics model. journal of nuclear materials, 329, 1219-1222. slater, j. c., & koster, g. f. (1954). simplified lcao method for the periodic potential problem. physical review, 94(6), 1498. https://doi.org/10.52131/jmps.2022.0302.0029 81 journal of materials and physical sciences volume 3, number 2, 2022, pages 81 95 journal homepage: https://journals.internationalrasd.org/index.php/jmps assessment of pesticide toxicity in selected pakistani fruits irum jamil1, zaheer ahmad1, muhammad imran khan2, fawad ahmad1* 1 department of chemistry, university of wah, quaid avenue, wah cantt., (47010), punjab, pakistan 2 research institute of sciences and engineering (rise), university of sharjah, sharjah 27272, united arab emirates article info abstract article history: received: october 13, 2022 revised: november 10, 2022 accepted: december 30, 2022 available online: december 31, 2022 persistent organic pollutants and heavy metals are damaging the environment. crops and fields are destroyed by the seepage of heavy metals from untreated industrial waste. the burning and incineration of a variety of items also contributes to main and secondary emissions of pollutants. the excessive usage of pesticides in pakistan causes contamination, which effects the ecosystem. although they increased life quality but also posed a significant health danger. the toxic properties of various pesticides and organic pollutants in pakistani fruits was observed by exceeding the mrls. the study aimed to stimulate discussion among pakistan's stakeholders about the dangers and toxicity of pesticides, as well as prompt plans for environmental cleanup and more environmentally friendly farming. due to ignorance, a sizable section of the populace is unaware of the issue of pesticide residues and their accumulation in the food chain. the major goal of the review is to record, evaluate, and examine the findings of earlier research on the levels of various pesticides in particular fruits from pakistan. the results of the earlier investigations made it abundantly evident that more than 50% of the samples were contaminated with pesticides such as organophosphate, pyrethroid, and organochlorine. keywords: pesticides organochlorine pollutants fruits © 2022 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: fawad.ahmad@uow.edu.pk 1. introduction science has undergone a revolution as a consequence of the commencement of technical innovations coupled with modernization of scientific understanding and enhanced accessibility (rasheed et al., 2022). a wide range of synthetic chemicals are employed in modern industry to create things we use every day including insecticides, food, colours, pharmaceuticals etc (baqar et al., 2017). environmental pollution has increased significantly over the past few decades as a result of rapid industrialization and enormous population growth (habiba et al., 2022). environmental pollution is attributable to natural contaminants that are then changed, either directly or indirectly, by human activities (conrad, white, santos, & sanders, 2021). environmental components are polluted as a result of human activities that frequently employ chemicals that are not acceptable for environment. this degradation of the environment puts living things at risk (mukiibi et al., 2021). https://journals.internationalrasd.org/index.php/jmps mailto:fawad.ahmad@uow.edu.pk journal of materials and physical sciences 3(2), 2022 82 figure 1: pesticide residues in some pakistani fruits and their potential health risks 2. problems associate with pollutants in recent decades, various regions of the world have reported increased concentrations of a wide range of contaminants or pollutants, including toxic heavy metal ions, inorganic anions, micro pollutants, and organic compounds like dyes, phenols, pesticides, humic substances, detergents, and other persistent organic pollutants (saxena, purchase, mulla, saratale, & bharagava, 2020). these hazardous chemicals' discharge into natural water bodies has wreaked havoc on the flora and wildlife and upset the ecological equilibrium (gonzález-gonzález et al., 2022). numerous of these contaminants not only have significant levels of environmental mobility and a high potential for bio accumulation in the food chain, but they are also chemically and biologically resistant (parra-arroyo et al., 2022). water is essential to life on earth, but it is heavily polluted by industrial pollution and pesticides. the textile industry is very important in the development of economy, but it also seriously pollutes the environment. the need for colours, stain-resistant clothing, and other hue items is growing in daily life, spurring the growth of the dyeing industry. these factories release toxic organic pollutants into the environment, including organic azo-dyes, surfactants, and phenolic compounds, which severely disturb the natural balance and have an adverse effect on all forms of life. these factories use enormous amounts of water and a variety of chemical substances for the dyeing process (ahila, vinodini, ancy jenifer, & thamaraiselvi, 2022). figure 2: a schematic representation of the synthetic dyes and pesticide cycle in several ecologies https://www.google.com/url?sa=i&url=https%3a%2f%2fwww.researchgate.net%2ffigure%2fa-schematic-view-of-the-pesticide-cycle-in-an-ecosystem_fig1_339370004&psig=aovvaw0rguu_usxx-mgvpaydhod7&ust=1678094511543000&source=images&cd=vfe&ved=2ahukewiu5qyru8t9ahxkpccchdofa6oqr4kdeguiardeaq https://www.google.com/url?sa=i&url=https%3a%2f%2fwww.researchgate.net%2ffigure%2fa-schematic-view-of-the-pesticide-cycle-in-an-ecosystem_fig1_339370004&psig=aovvaw0rguu_usxx-mgvpaydhod7&ust=1678094511543000&source=images&cd=vfe&ved=2ahukewiu5qyru8t9ahxkpccchdofa6oqr4kdeguiardeaq irum jamil, zaheer ahmad, muhammad imran khan, fawad ahmad 83 aquatic plants cannot photosynthesize when there is an increased concentration of colourful chemicals in the effluent combined with surface water. additionally, it has an impact on both human and animal health as well as the fertility of agricultural soil (cai et al., 2022). water shortages are caused by physicochemical changes in surface and subterranean water quality brought on by textile waste (teo et al., 2022). traditional treatment techniques are costly and ineffective at effectively removing organic pollutants from wastewater (pérez, lebrero, & muñoz, 2020). thus, the treatment of textile industry wastewater requires methods that are both economically and environmentally sound in order to prevent pollution and conserve natural resources without hindering this industry's expansion (t. u. rashid, kabir, biswas, & bhuiyan, 2020). toxic dyes impart harmful effect on fruits, vegetables and crops. humans are routinely exposed to potentially hazardous metals (ptms) through eating of vegetables, fruits, and cereal crops cultivated in contaminated areas, which is a major problem for food safety around the world (bicudo da silva, batistella, moran, celidonio, & millington, 2020). intensive agricultural chemical usage, urbanization, industrialization, open waste dumping, landfills, solid wastes, mining, and sewage/wastewater irrigation are a few examples of anthropogenic sources (a. rashid et al., 2020). the ability of plants to absorb metals is determined by either plant intake or soil-to-plant transfer factors of the metals, which are dependent on the species of plant (nawab, farooqi, xiaoping, khan, & khan, 2018). plants absorb hazardous metals from polluted soil solutions and/or deposits on their surfaces that are exposed to contaminated surroundings (riyazuddin et al., 2022). ptm concentrations in various foods vary depending on the soil composition, nutritional balance, metal permissibility, absorption capacity, and species selectivity (shahzad akhtar et al., 2022). when fruits, vegetables, and cereal crops are harvested, produced, transported, and sold, ptms from industry and vehicle emissions can also be released (y. k. khan, toqeer, & shah, 2022). many of these contaminants have significant levels of environmental mobility, a high potential for bioaccumulation in the food chain, and are not just chemically or biologically resistant (peña, delgado-moreno, & rodríguez-liébana, 2020). figure 3: different sources of major persistent organic pollutants in the environment 3. pesticides pesticides are chemical compounds that are used to control weeds, plant diseases and to enhance both the yield and quality of food products (s. tang et al., 2022). since most farmers are unaware of employing these chemicals, it is natural that these pesticides interact with the environment by changing the qualities of their hosts and causing negative journal of materials and physical sciences 3(2), 2022 84 effects. pesticides are absorbed by soil particles, which then transported to the plant and animal food chain. this has a negative impact on the ecosystem by producing acute or chronic illnesses in individuals of all ages. pesticides contain a variety of heavy metals, toxic chemicals, and pollutants which impart major risks to the aquatic ecology after they are released (dad et al., 2022). plants absorb hazardous metals from polluted soil solutions and/or deposits on their surfaces that are exposed to contaminated surroundings (guo et al., 2022). these contaminents effect the aquatic water bodies as well as they harm human health also. many water borne diseases like cholera, typhoid, hepatitis, gastroenteritis are caused by contamination in water (rao et al., 2022). the most essential component of ecosystem is soil (land) which can be contaminated by both organic and inorganic substances, including pesticides. the health of the soil is altered by surplus harmful compounds, which has adverse impact on the health of the crop, and animals (zhang et al., 2022). over use of fertilizers containing nitrogen boosts the prevalence of pests and diseases (villaseñor-ortiz, de mello prado, da silva, & lata-tenesaca, 2022). due to fertilizer and direct disposal of household trash to plants result in increased phosphorus levels in soil and ground water, which serve as significant barrier to nutrient uptake (rajmohan, chandrasekaran, & varjani, 2020). the ability of plants to absorb metals is determined by either plant intake or soil-to-plant transfer factors of the metals, which are dependent on the species of plant. plants absorb hazardous metals from polluted soil solutions and/or accumulates on their surfaces that are susceptible to hazardous surroundings (ahmad, nisar, & mehmood, 2022). the use of pesticides has undoubtedly enhanced agricultural production overall, but their lingering residues have a detrimental effect on both the environment and human health (jehan, muhammad, ali, & hussain, 2022). the danger to human life posed by dietary food, drinking water, and the residential risk brought on by pesticide residues has received a lot of attention (t. anwar, ahmad, & tahir, 2011). maximum residue limits (mrls), average daily intake (adis), and good agricultural practices are some of the concepts used to manage pesticides and their contamination of food items (gaps) (h. tang et al., 2021). when measuring the daily intake of a specific pesticide through food, information from nutritional surveys takes into account the specifics of regional eating patterns and the level of a need. to calculate the mrls for pesticides in food commodities, it is essential to take into account certain criteria, including adi, terminal residues, and dietary patterns (feng et al., 2015). 4. classification of pesticides the classification of pesticides is based on their origin, target organism, and chemical make-up. according to who, pesticides are classified on the basis of their chemical properties (garcia, bussacos, & fischer, 2008). some major pesticides present in pakistani peach, mango, guava and orange are: organochlorine, organophosphate, pyrethroid, triazines. pesticides can be produced artificially or naturally. pesticides like endosulfan, dieldrin, aldrin, lindane, and ddt are widely used in agriculture, largely to increase crop yields and safeguard crops from pests in order to meet the demands of a growing world population (okereafor, garba, okunola, & adamu, 2022). pesticides containing organochlorines (oc) are extremely poisonous and carcinogenic (baqar et al., 2018). pesticides have been linked to harm to the kidneys, liver, and brain system as well as cancer, immune insufficiency, disturbance of the reproductive process, and alteration or interference with the normal operation of the endocrine system (awasthi & awasthi, 2019). the use of natural pesticides as an alternative to synthetic pesticides is therefore strongly advised for food security and environmentally sustainable practices (mohamed, sharaf, ataweia, & bakry). chlorinated hydrocarbons, or ocs, are used to control mosquitoes and in agriculture. they are hazardous to many species and persistently persist because they are soluble in lipids, store in animal fatty tissue, and are subsequently transferred down the food chain (jayaraj, megha, & sreedev, 2016). oc pesticides have been banned in numerous nations across several continents, yet due to their great persistence, they are still found in the environment (sultan, hamid, junaid, duan, & pei, 2023). during world war ii, german chemists created organophosphorous pesticides (opps) (kunhikrishnan, shon, bolan, el saliby, & vigneswaran, 2015). organophosphorus pesticides include chlorpyrifos, profenophos, quinalphos, dimethoate, and phorate (fu et al., 2022). opps can be dissolved in water or organic solvents. they are less prone to contaminate and enter groundwater than chlorinated hydrocarbons, and some of them are harmful to the nervous system (freed, schmedding, kohnert, & haque, 1979). they are irum jamil, zaheer ahmad, muhammad imran khan, fawad ahmad 85 absorbed by plants, transferred to leaves and stems, and then fed to insects that eat leaves by those plants. around the world, opps are used as an alternative to oc insecticides to control insects in fruits, vegetables, and cereals. due of their widespread applicability, low persistence, and relative inexpensive cost, opps and carbamates are still employed (muhire, li, yin, mi, & zhai, 2021). opps are continue to be utilised because of their generally inexpensive cost, low tenacity and broad applicability. they work by blocking the enzyme acetylcholinesterase, and therefore disrupting the human and insect central nervous systems. exposure to opps is to blame for around 80% of hospitalizations resulting from pesticide poisoning in humans (tariq, afzal, hussain, & sultana, 2007). synthetic pyrethroid pesticides include cypermethrin, fenvalerate, deltamethrin and carbofuran (mehmood, arshad, mahmood, kächele, & kong, 2021). allethrin and bioallethrin, the first synthetic pyrethroids, were created in 1949 (ford, mahadeva, carbone, lacy, & talley, 2020). resmethrin, the first generation synthetic pyrethroid, was created in 1962 by changing the structure of naturally occurring pyrethrins to boost their stability in sunlight and insecticidal activity (narenderan, meyyanathan, & babu, 2020). the commercial utilisation of bioresmethrin, which was created in 1967 from resmethrin, began in the late 1960s. additionally, two new, strong pyrethroids called cypermethrin and deltamethrin were created (bhatt, zhou, huang, zhang, & chen, 2021). figure 4: classification of pesticides 5. pesticides in pakistani fruit pakistan, an agricultural nation, uses 22.2 million ha for crop production, of which 4.5 million ha are devoted to the production of fruits and vegetables (syed et al., 2014). due to increased domestic demand, manufacturing has significantly increased in recent years (organization, 2003). fruits and vegetables, like other crops, are vulnerable to pest assault. different pesticides are utilised in pakistan for defense, insect control, and weed eradication (m. khan, mahmood, & damalas, 2015). in order to control insect pests and various crop diseases, pakistan, a country with a large agricultural sector, uses a lot of organochlorine pesticides (oc), causing environmental contamination and human exposure as a result (li et al., 2004). unfortunately, oc pesticides and other agrochemical poisons affect more than half a million people each year in pakistan. toxic active components have accumulated in the food chain as a result of the heavy usage of pesticides (bhardwaj, sharma, abraham, & sharma, 2020). pakistan is the second-largest consumer of pesticides for agricultural use in south journal of materials and physical sciences 3(2), 2022 86 asia (elazzouzi et al., 2022). however, only a small portion of pakistani farmers (19%) are familiar of pesticide usage. there is a lot of evidence to suggest that farmers have abused and overused pesticides, particularly in cotton-growing regions (kim, kabir, & jahan, 2017). the biological monitoring studies have shown that due to occupational exposure, farmers are more likely to experience acute and chronic pesticide-related health consequences (s. rashid, rashid, tulcan, & huang, 2022). furthermore, there is an unique risk for field workers, fruit pickers, and an undesirable residue concentration in fruits when pesticides are used intensively (greater sprays than the allowed amount) in cotton areas (raza et al., 2023). mrl (maximum residue limit) can be defined as tolerant level to store residues in the food commodities, as already set by the usepa (al-zaidi, baig, muneer, hussain, & aldosari, 2019). figure 5: percentage distribution of different pesticides in pakistan although fruits and vegetables have varying residual pesticide levels, this may be because of the zone's varying climatic conditions (hot, humid, and cold), or because plant species vary (memon, bhanger, & akhtar, 2009). in pakistan in particular, irrigation is thought to be a prevalent practice and a quick means to contaminate food through soil and water. due to greater concentrations of dieldrin, ddt, methamidophos, and diazinon than the allowed threshold and mrl, more than 50% of the collected fruits and vegetables were determined to be contaminated (jiang et al., 2009). 5.1. peach peach (prunus persica) is a member of the amydyloidae, subfamily of rosaceae. rosaceae is the 19th largest plant family (azam, sarker, & naz, 2016) peaches are one of the most widely consumed fruits in the world and are both economically and nutritionally essential (faheem et al., 2015). china is the world’s biggest producer of peaches with an annual production of 15.8 million tonnes (bilal et al., 2022). pakistan is the world’s 25th larger producer of peaches with an annual production of 73900 tonnes and 0.3% export share (bilal et al., 2022). it is cultivated on 13819 hectares of land. peach is a staple food in pakistan’s northern region and the second most substantial stone fruit (zhao et al., 2015). peaches are mostly grown in pakistan's nwfp and baluchistan, as well as several low cold and early maturing cultivars in the potowar region of punjab. the most widely used cultivars in peshawar and swat region early grand include florida king 6-a and 7, 8, and 9 numbers. while golden early, shah pasand, and shireen are grown in baluchistan (faostat, 2016). even though pesticides are made for particular 74% 14% 9% 2% 1% percentage usage of pesticides in pakistan insecticides herbicides fungicides arcarides fermigants irum jamil, zaheer ahmad, muhammad imran khan, fawad ahmad 87 purposes, they were also infamous for having a negative impact on the environment (shazia akhtar et al., 2020). the statement that ocs are "poisonous to humans, animals, plants, and overall food webs" has been ratified. it is observed that detection of different pesticides in pakistani samples of peach lies within the residual limit (rana, asghar, haider, & davies, 2021; samad, akhtar, shahid, & ahad, 2019). table 1 comparison of detection of different pesticides in pakistani peach, their class and chemical formula (abbasi et al., 2022) compound name chemical formula chemical class general class eu mrl mg/ kg fao mrl mg/ kg log k at < 25 oc,(ph 5-7) detecti on range mg/kg β-endosulfan c9h6cl6o3s chlorinated cyclodiene insecticide 0.05 n.a 4.79 0.0083 chloropyrifos c9h11cl3no3ps organophospho rus insecticide 0.01 0.5 5.0*104 0.01130.1247 captan c9h8cl3no2s ntrihalomethylthi os fungicide 6 20 610 0.0144 alphacypermethrin c22h19cl2no3 parethroid insecticide 2 n.a 0.87*10 7 0.01150.3783 dieldrin c12h8cl6o organochlorine insecticide 0.01 n.a 5.4 0.0063 atrazine c8h14cln5 triazine herbicide 0.05 n.a 2.5 0.00839 lod: limit of detection, loq: limit of quantification, mrl: maximum residue synthesis, n.a: non-agriculture figure 6: analysis of different pesticide residues in pakistani peach 5.2. mango mango is regarded as the “king of fruits” among all fruits due to its widespread consumption throughout the world and numerous health advantages it provides to people of all ages (ahmed & jahanzaib, 2022). the most widely cultivated tropical fruit in south asia is the mango, which has now spread around the world (saeed akhtar, 2015). the national fruits of pakistan and india is mango since these countries produce the majority of the world's mangoes. it is pakistan's second-most popular area for consuming fresh fruit and a great source of vitamins, minerals, iron, sugar, fibre, and lipids. the third-largest exporter of mangoes worldwide is pakistan. hyderabad, r.y. khan, muzaffargarh, muzaffargarh, and multan are the principal mango-producing districts (fateh, mukhtar, mehmood, ullah, & kazmi, 2022). sindh produces about 400,000 lac tons of mangoes a year, of which 40% are sent to middle eastern countries. they are typically greenish in colour, sweet, and have an 0% 20% 40% 60% 80% 100% chlorinated cyclodiene organophosphorus n-trihalomethylthio parethroid organochlorine triazine pesticide residue concentrations quantified in peach samples eu mrl mg/kg detection range mg/kg journal of materials and physical sciences 3(2), 2022 88 irresistible aroma. popular varieties of mango grown in sindh include sindhri, langra, and many others. it is noticed that presence of imidacloprid, buprofezin and chlorpyrifos in different pesticides exceeds the permissible limits in mangos (farooq, arif, gogi, atta, & nawaz, 2019). table 2 screening of different pesticides, their maximum residue concentrations and detection range quantified in pakistani mangos (kumar et al., 2021) s.no. compound name chemical formula mrls mg/kg detection range mg/kg 1 lambda cyhalothrin c23h19clf3no3 0.20 0.05 2 cypermethrin c22h19cl2no3 0.70 0.08 3 acetameprid c10h11cln4 0.50 0.09 4 imidacloprid c9h10cln5o2 0.20 0.79 5 buprofezin c16h23n3os 0.01 0.09 6 chlorpyrifos c9h11cl3no3ps 1 1.4 figure 7: graphical representation of presence of different pesticide components in pakistani mango samples 5.3. guava in pakistan, the guava (psidium guajava), often known as the tropical apple, is a common fruit (shah, usman, fatima, & nawaz-ul-rehman, 2019). fruit contains 82% of water, 0.7 % protein, 11% of carbohydrates, as well as healthy doses of vitamins a, b, and c, minerals, and pectin. it has three to six times as much vitamin c as oranges, ten to thirty times as much as bananas, and roughly ten times as much as papaya (noonari, memon, wagan, mushtaque, & ismail, 2016). the guava plant is widely grown in punjab and sindh. it is a tropical tree that can adapt to the majority of climatic and soil conditions (d. khan et al., 2020). guava comes in third place among pakistan's principal fruits in terms of area and output, after citrus and mango, which cover 183.8 thousand hectares, 151.5 thousand hectares, and 63.5 thousand hectares, respectively. according to data, between 1999–2002 and 2004–2005, guava output climbed from 494.5 to 570.6 thousand tonnes, while guava area increased from 60.3 to 63.5 thousand hectares. after analysis of 0.2 0.7 0.5 0.2 0.01 1 0.05 0.08 0.09 0.79 0.09 1.4 0 0.3 0.6 0.9 1.2 1.5 pesticide residue concentrations quantified in mango samples mrls mg/kg detection range mg/kg irum jamil, zaheer ahmad, muhammad imran khan, fawad ahmad 89 different guava samples it is observed that maximum pesticides exceeds the residual limits (sana akhtar, yaqub, hamid, afzal, & asghar, 2018). table 3 detected concentrations of pesticides in different samples of guava and their maximum residual limit (f. anwar & rashid, 2007) s.no. pesticides chemical formula mrls (mg/kg) detected concentrations (mg/kg) 1 difenoconazole c19h17cl2n3o3 75 81.5 2 bifenthrin c23h22clf3o2 0.03 5.13 3 paraquat c12h14c12n2 0.01 6.6 4 imidacloprid c9h10cln5o2 1 1.65 5 diomethomorph c21h22clno4 0.25 0.48 6 chlorpyrifos c9h11cl3no3ps 0.05 0.06 7 lambda cyhalothrin c23h19clf3no3 0.02 0.05 8 cypermethrin c22h19cl2no3 0.05 0.84 9 acetameprid c10h11cln4 0.01 0.05 10 imidacloprid c9h10cln5o2 0.05 0.80 11 buprofezin c16h23n3os 0.30 0.16 figure 8: assessment of different pesticide residues in pakistani samples of guava 5.4. orange numerous tropical and subtropical nations worldwide grow citrus fruits. along with top nations like brazil, the united states, china, japan, and mexico, pakistan is one of the biggest producers of citrus (kinnow) fruit (aziz et al., 2020). in addition, both in terms of productivity and area, citrus is the main fruit crop in pakistan in terms of its complete fruit culture. these fruits are produced on 210.47 thousand hectares in the punjab province, with a production level of 2.29 million tons (kumar et al., 2022). 0% 20% 40% 60% 80% 100% lambda cyhalothrin cypermethrin acetameprid imidacloprid buprofezin chlorpyrifos lambda cyhalothrin cypermethrin acetameprid imidacloprid buprofezin pesticide residue concentrations quantified in guava samples mrls mg/kg detection range mg/kg journal of materials and physical sciences 3(2), 2022 90 table 4 screening of different pesticides in orange samples and their comparison with maximum residue limit (rehman et al., 2022). pesticide residue concentrations quantified in orange samples s.no. pesticides chemical formula mrls (mg/kg) detected concentrations (mg/kg) 1 acetameprid c10h11cln4 0.01 1.8 2 carbofuran c12h15no3 0.005 0.02 3 imidacloprid c9h10cln5o2 0.01 0.4 4 atrazine c8h14cln5 0.01 0.35 5 chlorpyrifos c9h11cl3no3ps 0.067 1.5 6 heptachlor c10h5cl7 0.005 0.25 7 β-endosulfan c9h6cl6o3s 0.025 0.45 8 α-cypermethrin c22h19cl2no3 0.067 7.01 figure 9: detection of pesticide concentration in pakistani orange samples conclusions and future perspectives pesticides are used to increase agricultural output, stop the spread of diseasecarrying insects, and kill or inhibit harmful pests. except for (cash crop) cotton, pesticides are not used in pakistan in ways that are likely to maximize advantage due to a lack of understanding within the farming community and a lack of adequate regulatory agencies (damalas, 2009). in the present study comparison of different results showed that peach samples have less pesticide residue while detection of pesticides in different samples of guava and orange exceeds the residual limit. both fruits are highly contaminated. misuse of pesticides cause harm. they are toxins, therefore exposing people to them could have fatal or negative effects. when pesticides are present in food products and accumulate in tissues have a direct harmful effect on human health. in the industrialized world, strict government restrictions based on accurate and trustworthy analysis have been put in place regarding the presence of harmful pesticide residues in food crop plants or soil may not be treated with any type of pesticides in this system, with the exception of suggested fertilizers, as the active ingredients in pesticides are toxic to crop plants. however, many remediation techniques have been recorded to clean up the damaged ecosystem. 1. vegetables are the staple meal in diet, and nutrition is unquestionably the main way humans are exposed to pahs. how and how much pahs are accumulated in the vegetables cultivated in agricultural areas is a major source of concern for scientists and local authorities. 0% 20% 40% 60% 80% 100% pesticide residue concentrations quantified in orange samples mrls (mg/kg detected concentrations (mg/kg) irum jamil, zaheer ahmad, muhammad imran khan, fawad ahmad 91 2. the main factor behind the high concentration of pahs in the environment appears to be the widespread use of natural gas as fuel. common fuels used in businesses and homes include natural gas and furnace oil. because gasoline is so expensive, compressed natural gas, or cng, is a common fuel for cars in pakistan. however, to date, pakistan has not made any effective attempts to determine the amounts of pahs in vegetables produced there. 3. the main causes of increased pesticide residues in agricultural commodities and thus higher risk of their exposure to end users are farmers' sole reliance on chemical pesticides is lack of training resources and knowledge and incorrect handling. 4. to increase farmers' understanding of pesticide use and proper handling, the government must impose strict controls on the production and distribution of pesticides as well as make training facilities and effective extension services easily accessible to the agricultural community. as a result, the danger of exposure will be lowered, and the harmful impacts of pesticides on the environment will be lessened. alternative pest management methods must be investigated, including biopesticides (natural or microbial-based products) and allelopathic plant extracts (allelochemicals). references abbasi, f., lashari, a. a., solangi, i. b., baig, j. a., kazi, t. g., & afridi, h. i. 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(2015). phenolic composition and antioxidant properties of different peach [prunus persica (l.) batsch] cultivars in china. international journal of molecular sciences, 16(3), 57625778. https://doi.org/10.52131/jmps.2022.0301.0022 14 journal of materials and physical sciences volume 3, number 1, 2022, pages 14 21 journal homepage: https://journals.internationalrasd.org/index.php/jmps synthesis and characterization of cnt/pva nanocomposites for electrical, thermal and morphological properties gulfam nasar1*, uzma khalil2, muhammad saleem khan3, qaisar nadeem4 1 department of chemistry, balochistan university of information technology, engineering and management sciences, quetta, pakistan 2 jinnah college for women, university of peshawar, pakistan 3 national center of excellence in physical chemistry, university of peshawar, pakistan 4 department of chemistry, university of zurich, winterthurerstr, 190, 8057 zurich, switzerland article info abstract article history: received: february 15, 2022 revised: april 12, 2022 accepted: june 28, 2022 available online: june 29, 2022 the goal of the current work is to bring a helpful substance to nanoscience and nanotechnology that might be a "problem solver" for ion storage. carbon nanotubes/ pva nanocomposites were prepared in five concentrations in aqueous medium following film formation. the resulting nanocomposites were characterized using “ac impedance spectroscopy, differential thermal analysis, thermal gravimetric analysis / (tg/dta) and scanning electron microscopy (sem)”. ionic conductivity of the nanocomposites was determined from impedance spectroscopy. cnt/pva nanocomposites exhibited lower conductivity as compared with cnt or pva separately. tg/dta graphs exhibited a regular pattern, showing an increase in the thermal stability. morphology of the prepared samples as shown by sem reveals a favourable polymer-filler morphological arrangement at the interphase, which is suggestive of a favourable compatibility between the polymer and the filler substance. keywords: pvc carbon nanotubes nanocomposites ionic conductivity ac impedance tga sem © 2022 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: gulfam.nasar@buitms.edu.pk, gulfamnasar@gmail.com 1. introduction the discovery of numerous carbon nanostructures, metal nanoparticles, and other unique structures has spurred advancements in nanoscience and nanotechnology since the second half of the twentieth century (kakani, 2004). metal nanoparticles and carbon nanostructures have numerous applications in a variety of sectors thanks to their distinctive thermal, electrical, magnetic, and optical properties (masciangioli & zhang, 2003). these materials can be used individually or as distributed media in matrices, host materials, and polymer nanocomposites (safadi, andrews, & grulke, 2002). for a variety of purposes, efforts are being undertaken to find the material that is best suited. although nanoparticles and nanocomposites have provided solutions to many contemporary challenges (nicolais & carotenuto, 2005), there is still unmet demand in this area, leading to the creation and development of fresh materials every day. the current study is yet another trial to add to the valuable and modern material that will serve the scientists working in the cotemporary field. 2. experimental 2.1. chemicals used poly vinyl alcohol (pva) 125,000 g / mol, nitric acid, multi walled carbon nano tubes cetyl trimethyl ammonium bromide ‘ctab’, de-ionized water of millipore grade was used as solvent. https://journals.internationalrasd.org/index.php/jmps mailto:gulfam.nasar@buitms.edu.pk mailto:gulfamnasar@gmail.com gulfam nasar, uzma khalil, muhammad saleem khan, qaisar nadeem 15 2.2. synthesis of cnt/pva nanocomposites 5 w/w % stock solutions of pva and required reagents were made. the same were used to prepare reagent solutions for synthesis of nanocomposites (sankar, kumar, & rao, 2004). the cnts were functionalized, with constant stirring with water. the contents were transferred to a glass tube and were ultra-sonicated for two hours. 5 ml solution of 5 molar nitric acid was dripped into the contents and thus subsequent mix was subjected to refluxing process 12 hours at 120 ̊c. the functionalized cnts were filtered and washed until ph 7 was obtained. the cnts were suspended in de-ionized water with the help of ctab whose 75 mg were dissolved in water before 10 mg cnts were introduced to it. after dilution to 100 ml, ultra-sonication was performed for 8 hours at 60 ̊c (laachachi et al., 2009). to make cnt-pva nanocomposites, the fractions of both the solutions were mixed in appropriate ratios using dilution formula. magnetic stirring was carried out for 24 hours and films were grown in petri dishes. appropriate sizes and shapes were obtained from the generated films for characterizing (rajendran & bama, 2010). 3. characterization the samples were subjected to the following characterization techniques. 3.1. electrical properties “ac impedance analyzer pgstat 302, manufactured by autolab, netherland” was used to study electrical behavior of cnt-pva nanocomposites (baskaran, selvasekarapandian, kuwata, kawamura, & hattori, 2007). 1 square centimeter sample piece from each composition was subjected to a three-probe measuring system of ac impedance analyzer (ulaganathan, pethaiah, & rajendran, 2011). the third electrode is used as a reference electrode in addition to two working electrodes having area of its cross section 1×10−4 cm2. the measuring frequency was set 1 hz–30 khz, while 10 mv amplitude was used at room temperature. 3.2. thermal analysis 5-8 mg sample of each composition was analyzed for thermal properties using “diamond tg/dta machine manufactured by perkin elmer instruments, usa” (rajendran, kesavan, nithya, & ulaganathan, 2012) with a uniform heating rate of 5 ̊c/minute from 30600 0c (rimez et al., 2008). 3.3. morphological analysis “scanning electron microscope sem sj-6490lvma manufactured by jeol, germany” was used to characterize morphology and dispersion of the cnt within the polymer matrix (kim & kim, 2006). the appropriate sizes of the samples of polymer nanocomposites were gold-coated utilizing sputter coater machine before sem analysis. for this purpose voltage of 5-20 kv was used while the resolution was kept from 500-100000x. the most suitable voltage and resolution was used to take micrographs of the cnt-pva nanocomposites. 4. results and discussion 4.1. ac impedance of pva/ cnt composites cnt-pva nanocomposites were characterized for electrical properties. a representative nyquist plots is shown in figure 1. semi-circular path exhibited by the cntpva nanocomposite is attributed to the conducting region of the nanocomposite. cnts being light-weight material exhibit low density and show a commendable degree of conductivity (zhao et al., 2008). they exhibit anisometric behavior that is quite significant in transforming a transition between non-conducing to conducting behavior by the incorporation into a polymer matrix. the individual surface properties of the components of journal of materials and physical sciences 3(1), 2022 16 the nanocomposite also play a major role in characterizing the electrical properties of the nanocomposite. detention of pva over the interfaces of cnts also plays a role in defining the electrical conductivity of the nanocomposite. the conductive behavior of cnt-pva nanocomposites is depicted from figure 2 that shows the circuit diagram of the prepared sample. the obtained results comply with previous findings (nam et al., 2012). the current study focuses more on the lower concentrations of the cnt unlike the earlier reported work, focused on higher concentrations of cnt (khan, shakoor, & nisar, 2010; wang & qiu, 2011). this aspect marks this study significant in understanding in terms of greater compatibility and economic feasibility. in figure 2, in order to obtain a good fit, an additional circuit component; warburg impedances is added (khan et al., 2010). the warburg element can be defined as “a common diffusion circuit element that is used to model or simulate semi-infinite linear diffusion, that is, unobstructed flow to a large planar electrode.” the "diffusion-limited processes" linked to the ionic conductivity of the cnt-pva nanocomposite is simulated using this component (zamri, zein, abdullah, & basir, 2011). 0 1000 2000 0 200 400 600 -z '' / k  z' k  figure 1: ac impedance spectrum of cnt-pva nanocomposite figure 2: circuit diagram of the cnt-pva nanocomposite bulk resistance (rb) of the nanocomposites was figured out from the frequency of a high range of nyquist plot (abraham, alamgir, & hoffman, 1995; bhattacharyya, salvetat, & saboungi, 2006). one can calculate ionic conductivity (σ) of the composite from eq. (1). gulfam nasar, uzma khalil, muhammad saleem khan, qaisar nadeem 17 σ = l / arb (1) ‘a’ shows the area of electrode (1 cm2) and ‘l’ depicts thickness of the cnt-pva nanocomposite sample film (0.001 cm). the values calculated through eq (1), are shown in table 1. the same results are displayed in graphical form in figure 3, indicating that the ionic conductivity increases with an increasing amount of cnt in the nanocomposite. this increase is attributed to mobility changes and carrier concentration of the cnt in the matrix of pva. due to the decrease in the inter-particulate distances, this change is enhanced further in the higher concentrations of cnt. a decreased distance between the particles ensures enhanced hopping activity resulting in overall ionic conductivity augmentation (rajendran, bama, & prabhu, 2010). table 1 bulk resistance and ionic conductivity of cnt-pva nanocomposites no. bulk resistance rb/ω ionic conductivity σ/s cm-1 1 4160.10979 2.4e-06 2 4064.04392 2.46e-06 3 3760.06404 2.66e-06 4 3319.64776 3.01e-06 5 2099.26807 4.76e-06 0 2 4 6 0.000002 0.000003 0.000004 0.000005 io n ic c o n d u c ti v it y ( )/ s c m -1 mass of the filler /mg figure 3: ionic conductivity of the cnt-pva nanocomposite figure 4: circuit diagram of the developed composites journal of materials and physical sciences 3(1), 2022 18 4.2. thermal analysis of pva /cnt composites figure 5 shows a tga thermogram of the generated samples of pva/cnt nanocomposites showing weight loss as a temperature-function. pva decomposes in two phases and is stable up to 265oc (ma, tang, & kim, 2008). around 350oc is the temperature at which the pva side chain decomposes, while 450oc is the temperature at which the pva backbone degrades (nasar, khan, & khalil, 2010; sriamornsak & kennedy, 2006). according to the tga for figures 87–89, weight loss for pva/cnt 1 mg, pva/cnt 3 mg, and pva/cnt 5 mg happened in three stages. first step weight loss was from 11% to 14%, attributed to vaporization of the water content. second phase of loss in mass was 53 to 56 %, due to combustion, up to 352oc. a weight loss of around 20% occurred mainly due to decomposition of side chains and degradation of pva to up to 600oc. dta also supports the results shown in figures 91-96. figure 5 compares tga, and figure 6 displays dta for various compositions. results indicate that the thermal stability somewhat increases as cnt concentration rises from 1 mg to 5 mg. the conclusion is also supported by a comparison of the degradation temperatures for various compositions. figure 5: tga of a: pva/cnt 1mg, b: pva/cnt 3mg, c: pva/cnt 5mg 0 100 200 300 400 500 600 w e ig h t % temperature o c a b c gulfam nasar, uzma khalil, muhammad saleem khan, qaisar nadeem 19 figure 6: dta of a: pure pva/cnt 1mg, b: pure pva/cnt 3mg, c: pure pva/cnt 5mg 4.3. scanning electron microscopy samples of various compositions of cnt/ pva nanocomposite were analyzed for assessing the morphology of nanocomposites between 5 kv and 20 kv. figure164 displays a network of functionalized cnts with uniform thickness, while figure 7 shows the cnt micrograph at x37000. the particular scam of the particular conductivity. it is noteworthy that nearly all cnts have the same diameter, which is between 30 and 45 nm. figure 7: sem image of the carbon nanotube, showing a mesh/ network of cnt 0 100 200 300 400 500 600 m ic r o v o lt s temperature o c a b c journal of materials and physical sciences 3(1), 2022 20 5. conclusion 1. pva/ cnts nanocomposites with five different concentrations of nanocomposites were synthesized in solution form which were converted to films. 2. thermogravimetric/differential thermal analysis (tg/dta), ac impedance spectroscopy, and scanning electron microscopy were used to characterise the nanoparticles in detail (sem). 3. the fillers created homogenous nanocomposites by being evenly distributed throughout the matrix. under the microscope, the filler is distributed uniformly throughout the matrix according to the surface morphology. 4. using sem, the size of the nanoparticles was examined, and it was observed that the diameter of cnt ranged from 30 to 50 nm. 5. films displayed a highly smooth surface topography and uniform morphology. however, the matrix's embedded particles could be seen and their sizes were determined. 6. it was discovered that the ionic conductivity of all the produced nanocomposites ranged from 10-6 to 10-4 scm-1. ionic conductivity varied in all cases depending on the filler content, from low to high. the lowest conductivity was observed to be in pva/cnt nanocomposites. 7. according to tg/dta, the w/w percent of the filler tends to rise with the increase in thermal stability in all produced nanocomposites. references abraham, k., alamgir, m., & hoffman, d. 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(2008). mechanical strength improvement of polypropylene threads modified by pva/cnt composite coatings. materials letters, 62(28), 4380-4382. https://doi.org/10.52131/jmps.2023.0401.0035 46 journal of materials and physical sciences volume 4, number 1, 2023, pages 46 60 journal homepage: https://journals.internationalrasd.org/index.php/jmps pani-based nanocomposites for electrical applications: a review farhad ali1, shaista noor1, fawad ahmad1*, shahbaz nazir2, gulfam nasar3* 1 department of chemistry, university of wah, quaid avenue, wah cantt., (47010), punjab, pakistan 2 punjab higher education department, govt. graduate college ravi road shahdara lahore pakistan 3 department of chemistry, faculty of basic sciences, balochistan university of information technology, engineering and management sciences, quetta (87100), pakistan article info abstract article history: received: april 23, 2023 revised: june 04, 2023 accepted: june 09, 2023 available online: june 30, 2023 including supercapacitors, rechargeable batteries, and fuel cells, conducting polyaniline (pani) has been widely used in electrochemical energy storage and conversion technologies due to its high conductivity, ease of synthesis, high flexibility, low cost, and distinctive redox properties. because of its poor stability as a super-capacitive electrode, pure pani cannot keep up with the rising demands for more n-active sites, better power/energy densities, and more stable molecular structures. these drawbacks as a super-capacitive electrode can be overcome by combining pani with other active materials such as carbon compounds, metal compounds, and other conducting polymers (cps). recent pani research focuses mainly on pani-modified composite electrodes and supported composite electrocatalysts for fuel cells and rechargeable batteries, respectively. due to the synergistic effect, pani-based composites with various unique structures have shown superior electrochemical performance in supercapacitors, rechargeable batteries, and fuel cells. pani typically functions as a conductive layer and network in different pani-based composite structures. this review also discusses n-doped carbon materials produced from pani because they are frequently employed as metal-free electrocatalysts for fuel cells. we conclude by providing a quick summary of upcoming developments and future research directions in pani. keywords: pani nanocomposites electrical doping n-doped carbon material © 2023 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding authors’ email: fawad.ahmad@uow.edu.pk, gulfam.nasar@buitms.edu.pk 1. introduction nanotechnology is important in enhancing the functional capability of electrical devices widely used today(hulla, sahu, hayes, & toxicology, 2015). due to vast advancements in electronic devices, extensive research has been focused on increasing the potential applications of electrical appliances. out of all the nanocomposites, i.e., ceramic, metal-based, and polymer-based, polymer-based nanocomposites are more widely used for their electrical properties, high conductivity, and enhanced stability(p. liu et al., 2019; x.-f. tan et al., 2016). due to their high sensitivity and capacity to reverse changes in their optical and electrical properties when exposed to specific liquids or gases, conducting polymers like polyaniline (pani), polypyrrole (ppy), and polythiophene (pth) have been used as sensing active layers in chemical sensors(t. zhang et al., 2020). polyaniline is one of the best conducting polymers used in research for its low cost, facile synthesis, and high mechanical stability(meriga et al., 2015; paramane, kumar, & materials, 2016). polyaniline (pani) is one of the most promising materials of particular interest due to its high electrical conductivity, dielectric behavior, and excellent-electrochromic optical properties(kumar, kumar, awasthi, & engineering, 2018; seiler & kindersberger, 2014). https://journals.internationalrasd.org/index.php/jmps mailto:fawad.ahmad@uow.edu.pk mailto:gulfam.nasar@buitms.edu.pk suqqyana fazal, fawad ahmad, khizar hussain shah, shabnam shahida, tauqeer ahmad, gulfam nasar 47 polyaniline is the best electrode material with a semi-flexible rod polymer family(zare et al., 2019). supercapacitors, electrochromic devices like photovoltaic cells, plastic batteries, display devices, microelectronics, chemically modified electrodes, corrosion protection, and polymer light-emitting diode (pled) displays are just a few examples of the electrical applications where it is widely used(althubiti, al-harbi, sendi, atta, & henaish, 2023; xue, fu, wang, xing, & zhang, 2016). the polyaniline (pani) bases can be divided into three different oxidation states. the fully reduced (lucoemeraldine base) or half-oxidized (emeraldine base) forms can both be partially oxidized to make them conductors. and three of its states have different morphologies(arteshi, aghanejad, davaran, & omidi, 2018; he, yan, xue, li, & wang, 2023). the entirely reduced form is called lucoemeraldine (lb), the half-oxidized form is called emeraldine (eb green), and the oxidized form is called pernigraniline violet color (pb). contrary to other conducting polymers, pani's conductivity can be adjusted by adjusting the levels of protonation and oxidation(goswami, nandy, fortunato, & martins, 2023; kroutil, laposa, povolny, klimsa, & husak, 2023). one of the most crucial properties of pani-based nanocomposites is their ability to offer total electrical, thermal, and mechanical insulation. polyaniline conducting polymer is a promising anode material for lithium-ion batteries due to its high li storage capacity. polyaniline has the stability, flexibility, and conductivity to create any matrix material. it efficiently produces organic and dyesynthesized solar cells utilizing conjugated polymers(khan, gul, baig, & akram, 2023; xie et al., 2023). numerous uses for polyaniline include the creation of flexible electrodes, antistatic coatings, electromagnetic shielding, actuators, supercapacitors, and electrochromic. rechargeable batteries, sensors, electronic devices, light-emitting diodes, conducting paints and glues, gas-separation membranes, coatings, etc., are just a few of the many applications pani could be used for. numerous studies have also been done on using pani in the aerospace industry (goswami et al., 2023; nguyen, soram, tran, kim, & lee, 2023). ghadaayadkhadim (nam et al., 2011) has shown that pani-based nanocomposites can be widely used as sensors, and electrochemical devices, to detect various gases. thin films made of polyaniline (pani) that integrate hydrogen sulfide (h2s) gas sensors have been developed by mehdi hassan(bezzon et al., 2019). in 2019, by electrochemically polymerizing aniline monomer with sulfuric acid in an aqueous solution, which alters its electrical resistance, functionalized single-wall carbon nanotubes (f-swcnt) with varying concentrations were created. polyaniline nanowires have been used by h. song(z. han et al., 2019) as chemo-resistive sensors in the solution phase. the capability of these electrical devices is improved by various composites of polyaniline with various carbon materials, such as activated carbon, porous carbon, carbon nanotubes, carbon nanorods, carbon fibers, and graphene(sadiq et al., 2023; zahid, anum, siddique, shakir, & rehan, 2023). in this review article, which has yet to be published, we present the synthesis of pani-based nanocomposites as well as their electrical applications. although numerous pani-based nanocomposites have been used to advance energy conversion and storage devices, these materials' review articles are not yet available. this review article focuses on new developments in energy storage technologies and cutting-edge pani-based nanocomposite technology, which improve electrical qualities by raising conductivity and cyclic stability. in this review paper, pani is endowed with and displays appropriate performance for usage in electrical applications. 2. polyaniline (pani) a conductive polymer member of the synthetic polymer family is called polyaniline (pani). due to its distinctive electrical, optical, and mechanical properties, it has garnered considerable interest from researchers. german chemists heinrich hörlein and paul morgan created polyaniline (pani) for the first time in 1862, but it took a long time for researchers to realize that it had conducting qualities. the first known organic conductive polymer was journal of materials and physical sciences4(1), 2023 48 pani, which was discovered to have electrical conductivity comparable to metals by bell labs researchers in 1963(okafor, popoola, popoola, uyor, & ogbonna, 2023). since then, pani has undergone substantial research, and several prospective uses for its electrical, optical, and mechanical properties have been investigated. it is regarded as one of the most promising conducting polymers in the market today for various applications in electronics, energy storage, and biomedicine(yang et al., 2023). emeraldine base (eb), emeraldine salt (es), pernigraniline base (pgb), pernigraniline salt (pgs), lucoemeraldine base (lb), and lucoemeraldine salt (ls) are just a few of the several forms of polyaniline (pani). these forms' levels of oxidation and protonation vary, which alters their optical and electrical conductivity characteristics. emeraldine base (eb), which has good electrical conductivity, stability, and environmental compatibility, is the most extensively researched and used type of pani(ekande, kumar, & waste, 2023). figure 1: polyaniline with various redox forms(dhand et al., 2015) 3. pani synthesis a variety of polyaniline synthesis methods has been discussed in the below section. methods include emulsion polymerization, sol-gel polymerization, electrochemical polymerization, and matrix polymerization. some methods, like oxidative polymerization, were used to prepare polyaniline(varghese, kr, kausar, & pinheiro, 2023). the graphene-based pani nanocomposites have been fabricated by various methods in the presence of graphene, rgo, or go, and the pani is in the form of nanoparticles: nanowires, nanofibers, hollow spheres, or nanorods. most graphene-based pani nanocomposites were prepared using in situ polymerization approaches, including in situ chemical oxidative polymerization(w. tan et al., 2023). suqqyana fazal, fawad ahmad, khizar hussain shah, shabnam shahida, tauqeer ahmad, gulfam nasar 49 3.1. in situ chemical oxidative polymerization in situ, chemical oxidative polymerization, which includes chemically oxidizing aniline monomers in the presence of oxidizing agents such as ammonium persulfate, ferric chloride, or hydrogen peroxide, is a frequently used method for producing polyaniline (pani) and its derivatives. this method involves dissolving aniline monomers in an acidic solution containing an oxidizing agent. the polymerization process is then started by heating the reaction mixture, which produces pani(ko, yeap, & bakar, 2023).pani can modify graphene through a variety of interactions, including covalent functionalization, noncovalent functionalization, and other processes. by carefully manipulating the reaction conditions, it is possible to create graphene-based pani nanocomposites with various topologies, including nanowires, nanofibers, nanoparticles, nanotubes, and nanorods. nanotubes having an outer diameter of 250 nm might be produced by polymerizing in 0.1 m aniline and 0.05 m hcl solution at 0 c for 90 minutes. it is crucial in determining how big the nanotubes are. a nanosphere shape was discovered as the solution acidity rose from 0.05 m to 0.2 m. this technique successfully creates hierarchical nanocomposites of pani nanowire arrays on go sheet substrate(imali, perera, kaumal, & dissanayake, 2023; y. zhao et al., 2015). 3.2. in situ electropolymerization electrochemical polymerization of aniline monomers on a conducting electrode surface is known as in situ electropolymerization, and it is a process used to create polyaniline (pani) and its derivatives. the electrode functions as a support for the polymerization process and a way to regulate how quickly the pani film grows. pani is created when aniline monomers undergo oxidation at the anode surface during the electropolymerization process. an acidic electrolyte solution containing aniline and an oxidizing agent, such as ammonium persulfate or ferric chloride, is commonly used to conduct the oxidation process(rathnayake et al., 2023). the creation of pani/go nanocomposites using in situ electropolymerization and their characteristics have been covered in several research. according to a study by zhang (2016), for instance, pani/go nanocomposites were created utilizing a two-step in situ electropolymerization technique, and it was demonstrated that the resulting materials exhibited outstanding electrochemical characteristics, making them ideal candidates for use as supercapacitors. similar to this, a 2019 study by xiong described the synthesis of pani/go nanocomposites utilizing an electrochemical co-deposition approach, demonstrating that the resulting nanocomposites exhibited large surface area and increased conductivity, making them exciting candidates for use as biosensors(eftekhari & kim, 2017; yong zhang, wang, lu, li, & zhang, 2021). 3.3. interfacial polymerization interfacial polymerization is a flexible method for creating several kinds of polymers, including polyaniline (pani). the process entails polymerizing two immiscible phases at their interface, commonly an organic and an aqueous phase(kyomuhimbo & feleni, 2023). an oxidant is often present in the aqueous phase of pani, whereas aniline and a dopant are typically present in the organic phase. the oxidant diffuses into the organic phase when the two phases come into contact at the interface, starting the polymerization of aniline into pani. the resulting pani is typically deposited at the interface as a thin film that can later be separated and treated(male, srinivasan, & singu, 2015). in a 2015 study, zhang reported on the interfacial polymerization process used to create pani/go nanocomposites. they demonstrated that the produced materials exhibited high specific capacitance, making them interesting candidates for use as supercapacitor electrodes. similarly, a 2017 work by yin described the creation of pani/go nanocomposites using interfacial polymerization and showed that the resulting nanocomposites had good catalytic activity for reducing nitroarenes(ji et al., 2015; wei, yang, hu, li, & jiang, 2021). journal of materials and physical sciences4(1), 2023 50 3.4. solution mixing the initial ingredients are disseminated in a common solvent and combined in solution mixing to create a homogeneous combination. the stability and dispersion of the nanocomposite are highly dependent on the solvent chosen. dimethylformamide (dmf), nmethyl-2-pyrrolidone (nmp), and water are frequently employed as solvents for combining pani and go solutions(q. wang et al., 2017). in the resulting pani/go nanocomposite, the go sheets are enmeshed inside the pani matrix, giving the material a composite structure. by modifying the preparation parameters, such as the concentration of the starting materials, mixing time, and temperature, the dispersion and distribution of the go sheets inside the pani matrix may be managed(chang, lin, peng, zhang, & huang, 2018). the pani/go nanocomposites were created by solution mixing, as described by li et al., and it was demonstrated that these nanocomposites exhibited good electrical conductivity and electrochemical characteristics, making them appropriate for supercapacitor electrodes. similarly, zhang described the solution-mixing method used to create pani/go nanocomposites and showed that these materials had a high catalytic activity for reducing nitroarenes(olad, barati, & shirmohammadi, 2011; rahmawati, suendo, & hidayat, 2018). 3.5. self-assembly approach in the self-assembly method, pani is created by guiding the assembly of pani monomers into nanostructures with regulated size, shape, and morphology using surfactants or templates(j. wu, wang, huang, bai, & science, 2018). the self-assembly method has several benefits, including gentle reaction conditions, excellent purity of the resultant pani, and controllable pani nanostructure characteristics. in the self-assembly method, pani nanocrystals are stabilized in aqueous or organic solvents using surfactants or templates(w. song et al., 2017). the pani monomers are next added to the mixture, where they go through a self-assembly process to create nanocrystals with precise size and shape. pani nanocrystals that have been produced can be further treated to create films, fibers, or other structures with the desired characteristics.(ran, tan, & nanocomposites, 2018). various surfactants and templates have been employed for pani self-assembly, including block copolymers, dodecyl benzenesulfonic acid, and cetyltrimethylammonium bromide (ctab). the preferred pani nanostructure features and the application requirements determine the best surfactant or template (d. zhang et al., 2018). zhang, x(x. song et al., 2021) synthesized self-assembled polyaniline nanowires for ultrasensitive ammonia gas detection. 3.6. pickering emulsion polymerization the emulsifier particles used in this method are typically inorganic substances like metal oxides, silica, or clay minerals(w. j. han, piao, & choi, 2017). organic ligands are surface-functionalized onto them to make these particles compatible with the monomer and solvent utilized in the polymerization process. an oxidizing agent is then introduced to the emulsion after the monomer, typically aniline, to cause the polymerization of the monomer into pani nanoparticles(huang et al., 2023). compared to conventional surfactant-based emulsions, pickering emulsion polymerization uses solid particles as emulsifiers and provides several benefits. for instance, the solid particles can stabilize the emulsion by reducing nanoparticle coalescence, which results in a more uniform size distribution(jun, kwon, choi, seo, & interfaces, 2017). additionally, following synthesis, it is simple to separate the solid particles from the polymer nanoparticles(y. wang, hu, luo, gu, & liu, 2021). r liu(k. wu, gui, dong, luo, & liu, 2022) prepared pani nanocapsules by pickering emulsion polymerization for anticorrosion coating. suqqyana fazal, fawad ahmad, khizar hussain shah, shabnam shahida, tauqeer ahmad, gulfam nasar 51 4. pani-based binary and ternary composites composite materials made of polyaniline (pani) are those in which pani has been combined with one or more other materials to produce a new material with improved or distinctive features. because pure pani has limitations in terms of its mechanical, electrical, and thermal properties, pani composites are required. pani composites can be customized to specific applications and desired qualities by integrating different components(althubiti et al., 2023). pani/graphene oxide, pani/carbon nanotubes, and pani/metal nanoparticle composites are a few examples of pani composites. when compared to pure pani, these composites have been found to have better mechanical strength, electrical conductivity, and other qualities(nasir et al., 2023). pani composites with two components are referred to as binary composites, while those with three components are referred to as ternary composites. by fusing pani with various materials, binary and ternary composites allow for even more precise control of characteristics(shanmuganathan, raghavan, & ghosh, 2023). 4.1. pani-based binary composites binary composites made from polyaniline (pani) and another element, such as graphene oxide, carbon nanotubes, metal oxides, or conductive polymers, are called polyaniline-based binary composites. compared to pure pani, the properties of the resulting composite can be enhanced or made to stand out(lee et al., 2017). the pani/graphene oxide composite illustrates a pani-based binary composite(yanlin zhang et al., 2016). this composite is a potential supercapacitor material due to its outstanding electrical conductivity and high specific capacitance(palsaniya, nemade, & dasmahapatra, 2018). another illustration is the composite of pani and carbon nanotubes, which has shown enhanced mechanical strength and thermal stability and is, therefore, appropriate for use in structural materials or high-temperature applications. the potential use of pani/zno and pani/tio2 composites in fields like photocatalysis and gas sensing has also been researched(gaikwad, patil, patil, naik, & b, 2017). usually, in situ, polymerization, solution mixing, or interfacial polymerization are used to create these binary composites. the qualities of the final composite can vary depending on the preparation process chosen. figure 2: synthesis protocol for a-mno2/pani binary composite (dessie, tadesse, eswaramoorthy, & adimasu, 2021) all things considered, pani-based binary composites are a significant class of materials with a variety of possible uses (torvi, naik, & kariduraganavar, 2018). they are journal of materials and physical sciences4(1), 2023 52 appealing for usage in a variety of industries, including energy storage, electronics, and biology, due to their improved features and distinctive qualities (omar et al., 2017).yilkal dassie(dessie, tadesse, eswaramoorthy, & adimasu, 2021) prepared a mno2/pani binary composite as an efficient anode catalyst for microbial fuel cells. 4.2. pani-based ternary composites pani-based ternary composites comprise three distinct parts comprising pani and two other substances, such as metals, metal oxides, or other polymers. these composites are made to maximize the benefits of each component's unique characteristics, producing a material with improved electrical, mechanical, or optical capabilities(azman, mamat@ mat nazir, ngee, & sulaiman, 2018). pani/fe3o4/go, a ternary composite made from pani, iron oxide (fe3o4) nanoparticles, and graphene oxide (go), is an illustration of a pani-based ternary composite(mezgebe et al., 2017). thanks to the go, the fe3o4 nanoparticles give the composite magnetic characteristics and have a high surface area and strong electrical conductivity. the pani keeps the composite together as a binder and improves its electrical characteristics(mu, tang, zhang, & wang, 2017). this composite is a potential material for emi shielding applications since it has been demonstrated to have better electromagnetic interference (emi) shielding effectiveness than pani/fe3o4 binary composites(luo et al., 2015; hou wang et al., 2015). pani/fe3o4/mos2 is another illustration; it is made up of pani, fe3o4 nanoparticles, and mos2. while fe3o4 enhances electrical conductivity and serves as a template for pani growth, mos2 nanoparticles provide uv-blocking properties and act as reinforcement. the usage of this composite in uv-blocking, magnetic, conductive, dielectric, and photocatalytic applications has shown promise(x. wang et al., 2022). 5. electrical properties of pani a conductive polymer with electrical characteristics, polyaniline (pani) can undergo reversible redox reactions. it is a specific kind of conjugated polymer with delocalized electrons that can conduct electricity. duan and yuan(2022)(b. liu et al., 2022)explained the pani conductivity mechanism. they suggested that protons are transferred from the dopant to the polymer backbone as part of the doping process in pani, producing charged sites that serve as mobile charge carriers. these charged sites cause the delocalized -electron system to develop in the polymer backbone, which gives pani its electrical conductivity. 5.1. effect of dopants on electrical properties of pani doping degree, chemical structure, molecular weight, and morphology are just a few variables that can affect pani's electrical conductivity. pani can suffer pand n-type doping depending on the dopant employed. as a result of the dopant accepting electrons from the pani backbone during p-type doping, there are fewer charge carriers and more electrical resistance. in contrast, n-type doping increases the number of charge carriers and decreases electrical resistance as the dopant donates electrons to the pani backbone. double doping of pani, which is done by adding sulfuric acid, is also important while enhancing the electrical properties of pani. hisham a. saleh (2022) (saleh & younis, 2022) studied how polyaniline's (pani) electrical characteristics are affected by double doping. according to the study, pani's electrical conductivity and thermal stability both improve due to the double doping method. the findings also demonstrate that the twofold doping procedure reduces the bandgap of pani, which is advantageous for its use in electrical devices. in conclusion, the work offers insightful information about the potential of double doping to improve pani's electrical characteristics.awzarmanaf(manaf, hafizah, & riyadi, 2019) showed variation in electrical conductivity of pani by anionic surfactant as shown in fig below. suqqyana fazal, fawad ahmad, khizar hussain shah, shabnam shahida, tauqeer ahmad, gulfam nasar 53 figure 3: electrical conductivity of pani by sds (manaf et al., 2019) 6. electrical applications of pani polyaniline (pani) has a variety of electrical applications due to its unique electrical properties including 6.1. supercapacitors supercapacitors, often called electrochemical capacitors, are energy storage systems capable of storing a lot of energy and power. they are appropriate for various applications, including electric vehicles, portable devices, and renewable energy systems, since they offer fast charging and discharging capabilities(n. ma, yang, riaz, wang, & wang, 2023). panibased materials can be used to overcome the poor energy density of conventional supercapacitors, which restricts their use in many applications. since pani-based composites have a high specific capacitance and good cycling stability, they have been thoroughly studied for use in supercapacitors. pani/graphene oxide (go) is one such composite, and due to the synergistic interaction between the two materials, it possesses a high specific capacitance. a specific capacitance of up to 900 f/g, which is substantially higher than that of pure pani, has been observed for pani/go composites. pani/carbon nanotubes (cnts) are another pani-based composite that has been researched for application in supercapacitors. due to the high surface area and good electrical conductivity of the cnts, pani/cnt composites have a high specific capacitance and exceptional cycling stability. there have been reports of pani/cnt composites with a specific capacitance of up to 450 f/g(eftekhari, li, & yang, 2017). pani-based hydrogels have also been investigated for usage in supercapacitors in addition to these composites. pani hydrogels have a three-dimensional porous structure that offers a significant surface area for electrolyte ion adsorption, resulting in high specific capacitance. according to some reports, pani hydrogels can have a specific capacitance of up to 711 f/g(sardana, gupta, singh, maan, & ohlan, 2022). overall, improving supercapacitors' energy density and cycling stability by introducing pani-based materials has shown considerable potential. more research is required to enhance the synthesis and performance of these materials and investigate their potential for usage in real-world applications(mir, kumar, & riaz, 2022). 6.2. fuel cells fuel cells are machines that use a chemical reaction to transform chemical energy from fuel into electrical energy. for its possible use as an electrode material in fuel cells, polyaniline (pani) has undergone substantial research(q. xu et al., 2022). pani is a prime candidate for application in fuel cells due to its demonstrated strong electrochemical journal of materials and physical sciences4(1), 2023 54 activity, high electrical conductivity, and strong chemical stability. proton exchange membrane fuel cells (pemfcs), direct methanol fuel cells (dmfcs), and microbial fuel cells (mfcs) have all used pani as a cathode and anode material(dessie, tadesse, & adimasu, 2022; huanhuan wang, lin, shen, & devices, 2016). pani is a cathode material used in pemfcs, where it can catalyze the oxygen reduction reaction that results in the production of electrical energy. the methanol oxidation reaction can be catalyzed by using pani as an anode material in dmfcs(papiya, pattanayak, kumar, kumar, & kundu, 2018). pani can be employed as a cathode material in mfcs, enhancing the fuel cell's electrochemical performance and stability(papiya et al., 2018; sudarsono et al., 2022). pani composites and hydrogels have been employed in numerous research investigations for fuel cells. in one such study, x. yang (2023) (y. xu et al., 2023) discusses creating and applying a composite material comprised of porous carbon nanoparticles and polyaniline in microbial fuel cells. the authors discovered that the composite material performed better than pure polyaniline and other composite materials with a maximum power density of 700 mw/m2 and a current density of 1200 a/m2. the better performance was due to the porous carbon nanoparticles' greater conductivity and active spots for electrochemical processes. the study shows the potential of composite materials based on polyaniline for enhancing the efficiency of microbial fuel cells. cc xing (2022) (d. jiang et al., 2022)demonstrated that with a maximum power density of 800 mw/m2, the composite material pani/mxene/-coated carbon cloth yielded excellent electrochemical performance and outperformed many previously reported mfc anode materials. the performance of the mfc was strengthened by the authors' observation of increased bacterial adherence on the anode surface. the findings imply that the carbon cloth coated with polyaniline-mxene may be a potential anode material for highperformance mfcs. 6.3. rechargeable batteries due to its high theoretical specific capacity, quick electron and ion transport, and simplicity of production, polyaniline has received substantial study as an electrode material in rechargeable batteries. numerous rechargeable battery systems, including lithium-ion, sodium-ion, and zinc-ion batteries, have used pani. pani-based electrodes have demonstrated remarkable electrochemical stability and performance results, highlighting their potential as a workable substitute for conventional electrode materials(ahmad, farooqui, & hamid, 2018; f. zhang et al., 2017). supercapacitors are machines that can store electrical charge and quickly release it when necessary(zhu et al., 2022). pani-based materials can be employed as active materials in these machines. pani's unique electrical and mechanical qualities make it highly suitable for energy storage applications(h. jiang et al., 2022). a new anode material for lithium-ion batteries (libs) based on a composite of polyaniline (pani) matrix with sulfonated graphene-encapsulated fe2n nanoparticles was described by m. idress (2023)(idrees et al., 2023), along with its production and electrochemical characteristics. the pani matrix contains well-dispersed and evenly distributed fe2n nanoparticles, which enhances the anode's overall electrochemical performance. comparing the composite anode to its pani and pure fe2n equivalents reveals that it has a higher specific capacity, superior cycle stability, and rate capability. fe2n nanoparticles, sulfonated graphene, pani's high electrical conductivity, and pani's electrochemical activity are all said to work together synergistically to improve the composite anode's electrochemical characteristics. according to the study, composites based on pani could make potential anode materials for high-performance libs(hu, jia, & song, 2017; sarkar et al., 2016). 6.4. metal electro catalyst metal electrocatalysts are substances that reduce the activation energy of an electrochemical reaction to improve the pace of the reaction. they are frequently utilized in batteries and fuel cells for energy conversion and storage(s. zhang et al., 2023). due to pani's strong electrical conductivity, good electrochemical stability, and capacity to bind suqqyana fazal, fawad ahmad, khizar hussain shah, shabnam shahida, tauqeer ahmad, gulfam nasar 55 metal ions, it is utilized as a metal electrocatalyst. metal ions like pt, pd, and ni can be added to pani to create composite materials with increased catalytic activity. these composites have proven to be efficient in several applications, including hydrogen evolution reactions (her) in water electrolysis and oxygen reduction reactions (orr) in fuel cells(l. zhang et al., 2017; s. zhao et al., 2023). for effective electrocatalytic co2 reduction, polyaniline gold nanoparticle core-shell nanofiber (pani|au) synthesis is described by th wang(t.-h. wang, lin, huang, & li, 2023). when compared to pure pani, the pani|aunanofiber has significantly higher electrocatalytic activity and excellent selectivity.l.zhang(j. zhang et al., 2022) also synthesized pd/pani/ti composite as an electrocatalyst due to the high surface area of polyaniline. they showed that the degradation efficiency of 2,4-dcp was up to 96.54%, which proves pani to be a promised material being used as an electrocatalyst. 7. comparison in tabulated form table 1 various pani composites for electrical applications pani nanocomposite method of synthesis application capacitance and cycles reference v2ct2x/mxene/pani in situ oxidation zn ion batteries 267.7mah/g (l. wang et al., 2023) pani/c carbonization electrode in supercapacitor. 372f/g 78% after 6000 cycles. (uppugalla, male, & srinivasan, 2014) pani/fe3o4 in situ polymerization supercapacitor 620f/g 85% after 2000 cycles. (y. ma et al., 2019) cowo4/pani chemical oxidative polymerization electrode for energy storage devices 653f/g 93.3% after 5000 cycles. (rajkumar, ezhilarasi, saranya, merlin, & solids, 2022) cuv2o6/pani in situ polymerization supercapacitor 375f/g 98% after 2000 cycles. (barik, barik, tanwar, & ingole, 2022) pani/pd thermal evaporation technique direct alcohol fuel cell 3ma/cm2 for methanol (eswaran, rahimi, pandit, chokkiah, & mijakovic, 2023) znin2s4/pani/tio2/ti coating method photocatalytic fuel cell 18.83 uw power density (mou et al., 2023) conclusion and future perspectives pani is regarded as one of the helpful intrinsic and electronic cps, and this paper carefully details the uses of pani in the field of electrochemical energy storage and conversion. it is suggested that pani be used in different fields, which can considerably expand its area of usage. pani is known to have many distinctive and promising features, and it is expected to be beneficial in electrical devices to enhance their electrical properties. due to the synergistic effect, pani generally serves as a conductive layer and network in various pani-based composite structures, and the resulting pani-based composites with various unique structures have demonstrated superior electrochemical performance in supercapacitors, rechargeable batteries, and fuel cells. however, there are still some drawbacks that could be resolved. pani is difficult to maintain a stable structure due to the de-doping phenomenon caused by light, electricity, magnetism, thermal, etc. also, pani is challenging to commercialize in the electrochemical field due to its relatively high cost and low practicability compared to conventional inorganic materials. it is challenging to balance the mechanical qualities and electrochemical performance when using pani in electrochemical energy storage technologies such as supercapacitors, rechargeable batteries, and fuel cells. for instance, pani coating could reduce the instability of nano-fluids brought on by nanoparticles' slow sedimentation (or scale formation) concurrent with agglomerating or clustering of nanoparticles inside the base fluid. journal of materials and physical sciences4(1), 2023 56 by reading this review, researchers can learn about pani's inclination to develop new technologies in the area of electrochemical energy storage and conversion. in conclusion, future advancements will necessitate ongoing research and endeavors in designing distinctive nanostructures of pani with higher surface areas and conductivities, extending application fields, and developing cost-effective manufacturing technologies. reference ahmad, a., farooqui, u., & hamid, n. j. r. a. 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(2022). rechargeable batteries for grid scale energy storage. 122(22), 16610-16751. https://doi.org/10.52131/jmps.2020.0102.0007 58 journal of materials and physical sciences volume 1, number 2, 2020, pages 58 77 journal homepage: https://journals.internationalrasd.org/index.php/jmps doping effect and microstructure behavior of rare-earth element cerium (ce+3) in barium hexaferrite (bacexfe12-xo19) nanoparticles zaheer abbas gilani1, awais ahmed1, h. m. noor ul huda khan asghar1*, muhammad khalid2 1 department of physics, balochistan university of information technology, engineering & management sciences, quetta 87300, pakistan 2 department of physics, university of karachi 24700, pakistan article info abstract article history: received: september 07, 2020 revised: october 30, 2020 accepted: november 29, 2020 available online: december 31, 2020 cerium substituted bam hexaferrites bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nano crystallites were synthesized via sol-gel method. the x-ray diffraction (xrd) patterns were analyzed by rietveld refinement which confirms the formation of hexagonal structure. the crystalline size was calculated by debye scherrer method, w–h method and ssp method. the lattice constant ɑ found to decrease, this was due to the octahedral site replacing a large radius of ce3+ ion with a smaller radius fe3+ ion, while the lattice constant c found increase. the x-ray density observed increases with increasing ce3+ concentration. fourier transform infrared spectroscopy (ftir) confirmed the two frequency bands ʋ1 tetrahedral site and ʋ2 octahedral site in a range between 400–620 cm-1. impedance analyzer was used to investigate the dielectric properties in a range of 1 mhz – 3 ghz following maxwell wagner model. dielectric constant showed decreasing trend while dielectric loss showed dispersive behavior by increasing frequency and same was that with tangent loss, such behavior was due to koop's phenomenological theory. ac conductivity exhibits a plane behavior in a low frequency, while dispersive in high frequency. such behavior was due to grain effect at high frequency. impedance showed continuous action at high frequency, which is attributed to the release of space charges. the real and imaginary modulus showed variation by increasing frequency, which was due to the occurrence of relaxation phenomenon. as per dielectric research, these ferrites can be utilized in high frequency devices, microwave technologies, and semiconductor devices. keywords: hexaferrites sol-gel xrd rietveld crystalline size ftir dielectric analysis © 2020 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding author’s email: noorulhudakhan@gmail.com 1. introduction nanotechnology research is becoming one of the most important and rapidly expanding fields. nano-sized ferrites, in particular, are being studied to improve their structural and electrical properties in order to make them suitable for high frequency applications and other advanced electronic devices (n. singh, agarwal, sanghi, & singh, 2011). last few years, scientists are showing interest in hexagonal ferrites. there are different types of hexagonal ferrites which are also famous as hexaferrites have their long journey since their discovery, (jasrotia, singh, sharma, kumar, & singh, 2019; jasrotia, singh, sharma, & singh, 2019) one of them is m-type ferrites, barium ferrite or bam (bafe12o19). hexagonal m-type barium ferrite (bafe12o19) and its doping element cerium (ce+3) have attracted a lot of interest due to its technological uses in permanent magnets https://journals.internationalrasd.org/index.php/jmps mailto:noorulhudakhan@gmail.com zaheer abbas gilani, awais ahmed, h. m. noor ul huda khan asghar, muhammad khalid 59 and prospective applications in high density magnetic recording media and microwave devices, big crystalline anisotropy, large magnetism, strong intrinsic coercivity, great chemical stability, high curie temperature, and cheap cost characterize barium hexaferrites (hussain et al., 2011; iqbal, ashiq, hernández-gómez, muñoz, & cabrera, 2010; martirosyan, galstyan, hossain, wang, & litvinov, 2011). due to their outstanding magnetic and dielectric characteristics, hexaferrites might be regarded one of the finest magnetic materials for electromagnetic wave absorbers (c.-j. li, wang, & wang, 2012). barium hexaferrite has been extensively investigated as one of the most significant microwave absorption materials due to its outstanding magnetic and microwave characteristics (choopani, keyhan, ghasemi, sharbati, & alam, 2009; l. li et al., 2013). generally, resistivity of barium ferrite is very high so, the dominant absorbing mechanism is magnetic loss (p. singh et al., 2006). hence, an improvement in the intrinsic magnetic properties such as saturation magnetization and magneto crystalline anisotropy or coercivity can enhance their microwave absorbing ability. one of the most essential instruments for satisfying a wide range of uses is doping some suitable elements in the parent material. the structural and electromagnetic behavior of ferrites are tailored by the synthetic methods and doping of various rare earth/transition metal ions in hexagonal structure (al-hilli, li, & kassim, 2009). the intrinsic properties of ferrites like permittivity, dielectric losses and conductivity are controlled by chemical composition, annealing treatment and type of doped metal ions (al-hilli, li, & kassim, 2012; jing, liangchao, & feng, 2007). magnetic and dielectric properties can be improved by elemental substitutions to ferric (fe+3) sites. researchers reported, when cerium (ce+3) is doped in barium hexaferrite, the microwave absorbing ability is considerably enhanced, suggesting that (bacexfe12-xo19) can be utilized in microwave technology, high storage devices, and electronic components (chang, kangning, & pengfei, 2012). the present study, the barium hexaferrite (bacexfe12xo19) having cerium (ce+3) as a substituent are prepared via solgel method. in this work, the doping effect and microstructure behavior of cerium (ce+3) in barium hexaferrite with general formula bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, 1.0) has been investigated. the prepared ferrite material is characterized by x-ray diffraction (xrd), fourier transform infrared spectroscopy (ftir) and dielectric properties analysis. 2. experimental the cerium (ce+3) substituted barium hexaferrite (bacexfe12-xo19) nanoparticles were effectively produced through different cerium (ce+3) concentrations (x = 0.0, 0.25, 0.5, 0.75, and 1.0) using solgel method. the materials used were comprise of barium nitrate [ba (no3)2 (m.w = 261.34)] with molarity of 0.1, cerium nitrate [ce (no3)3 (m.w = 434.22)] with molarity of 0.1, ferric nitrate [fe (no3)3.9h2o (m.w = 404)] with molarity of 1.2, and citric acid [c6h8o7.h2o (m.w = 210.14)] with molarity of 1.3, stayed systematically through physical balance. the distilled water was used for the sample preparation. all the mixtures were kept on the hot plate magnetic stirrer at 80oc for 3 hours. the evaporation was done in the thermostat oven at 90oc. after grinding, the samples were annealed at 900oc for 3 hours in box-type resistance furnace. the x-ray diffraction (xrd) was carried out on (panalytical x'pert pro) by rietveld refinement process to analyze the crystal structure and to find various structural parameters of materials pertaining to the crystalline structure. the crystalline size of the prepared samples was confirmed by x-ray diffraction (xrd) measurements via debye scherrer formula. the 2 = 32° extremely intense peaks of (107) hkl formed, which were an ideal peak for hexaferrite nanoparticles. the crystalline size was also investigated by wh method and ssp method. the fourier transform infrared spectroscopy (ftir) analysis was done and investigated the two frequency bands which were 1 and 2 in the range of 400 – 500cm-1 and 500 – 620cm-1. these two investigated bands were associated with tetrahedral and octahedral starching bands. the dielectric analysis was used to investigate the dielectric properties of prepared material. various dielectric parameters like dielectric constant, dielectric loss, tangent loss, alternation current (ac) conductivity, real and imaginary part of impedance and modulus were calculated in the frequency range of 1 mhz – 3 ghz. journal of materials and physical sciences 1(2), 2020 60 3. results and discussion 3.1. xrd analysis the cerium (ce+3) doped barium hexaferrites formed by solgel method are seen in the common configuration of materials with bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0). to ensure that the crystal shape and size the (panalytical x'pert pro) is used for x-ray diffraction (xrd) characterization. this is a very useful and important characterization procedure that determines various structural parameters of materials of various compositions, such as lattice constant, crystallite size, unit cell length, x-ray density and bulk density, dislocation density, stacking fault, lattice strain and micro strain, and cell volume. the crystalline stage of the prepared samples is confirmed by x-ray diffraction (xrd) measurements. the most intense peaks of all the samples are observed at angle 2 = 32° having (107) hkl miller indices, which are ideal peaks for hexagonal structure. (lodhi et al., 2014) no impurity phase is detected in xrd analysis. the peaks corresponding to xray diffraction (xrd) pattern are studied and are indexed as (006), (107), (205), (1011), (218), and (2014), which confirms the hexagonal structure. these peaks are verified by jcpds card number 00-027-1029. in (figure 1), the xrd pattern of the prepared samples bacexfe12-xo19 with different ce+3 concentration (x = 0.0, 0.25, 0.5, 0.75, and 1.0) is displayed. figure 1: x-ray diffraction (xrd) analysis of cerium substituted barium hexaferrites bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles rietveld refinement via full prof suit was also used to examine the x-ray diffraction pattern. the rietveld refinement approach is a potential method for analyzing detailed crystal structure information from powder diffraction data. the rietveld-refined diffraction xrd pattern of angle 10°–80°, annealed at 900 °c, is presented in (figure 2). zaheer abbas gilani, awais ahmed, h. m. noor ul huda khan asghar, muhammad khalid 61 all of the xrd patterns were studied using the rietveld refinement approach in hexagonal symmetry with the p63/mmc space group. different parameters were refined in sequence, such are background and scale factor, profile shape, width parameters, asymmetry atomic coordinate and site occupancies. the peak shape function is studied by using pseudo-voigt approximation which is the combination of lorentzian and gaussian component. the rietveld refinement of xrd patterns of bacexfe12-xo19 at (x = 0.0, 0.25, 0.5, 0.75, 1.0) is shown in (figure 2). where, the observed data is shown by a black solid circle, the calculated intensities by a red solid line, the bragg's positions by vertical pink lines, and the bottom blue lines represents the difference between observed and calculated intensities. the successful rietveld refinement is dependent on the peaks shape, the refinement results are not successful if peaks are not correctly described (manglam, kumari, mallick, & kar, 2021). however, the data we have well-resolved peaks in the diffraction pattern, where observed and calculated intensities are matching to each other, and also well matched with jcpds card number 00-027-1029, which confirm the formation of bhf nanoparticles. the observed diffraction peaks corresponding to reflection planes (006), (107), (205), (1011), (218), and (2014) provide clear evidence for the formation of bhf nanoparticles. figure 2: rietveld refinement analysis of ce+3 substituted barium hexaferrite bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles the crystal structure obtained from rietveld refined parameters by using vesta software is shown in (figure 3), where ba atoms indicated as red, fe atoms as light violet and oxygen as bark blue. the structure of bhf is covered with irons and oxygen layers, where iron atoms are arranged in tetrahedral and octahedral holes, excluding one set of fe atoms which is linked with five o atoms. so, the bhf includes 18 octahedral, 4 tetrahedral, and 2 bipyramids fe atoms in a single unit cell which is shown in (figure 3), and the values of atomic parameter of ce+3 substituted bafe12o19 at (x = 0.0) is given in (table 1). journal of materials and physical sciences 1(2), 2020 62 figure 3: schematic diagram of crystal structure of barium hexaferrite bafe12o19 at (x = 0.0) table 1 atomic parameter of the barium hexaferrite bafe12o19 at (x = 0.0) atom x y z occ site ba+2 23 13 14 1 2d fe+3(1) 0 0 0 1 2a fe+3(2) 0 0 14 1 2b fe+3(3) 13 23 0.028 1 4f fe+3(4) 13 23 0.189 1 4f fe+3(5) 0.166 13 0.108 1 12k o-2(1) 0 0 0.151 1 4e o-2(2) 13 23 0.055 1 4f o-2(3) 0.19 0.38 0.052 1 6h o-2(4) 0.16 0.32 14 1 12k o-2(5) 12 1 0.15 1 12k the formula (1) is used to measure the lattice constants ɑ and c of ce+3 substituted bacexfe12-xo19 nanoparticles: 𝟏 𝒅𝒉𝒌𝒍 𝟐 = [ 𝟒 𝟑 𝒉𝟐+𝒉𝒌+𝒌𝟐 𝒂𝟐 + 𝒍𝟐 𝒄𝟐 ] (1) where ɑ & c are lattice constants and dhkl is the distance between planes (h k l). the average lattice constant ɑ is estimated to be between 5.82 – 5.89 å. the ionic radius of ce3+ and fe3+ is used to characterize variations in the ‘ɑ’. with the replacement of ce3+ ion the lattice constant ɑ is found to decrease, this is due to the octahedral site replacing a broad radius of ce3+ ion (1.034 å) with a smaller radius fe3+ ion (0.64 å). the lattice constant ɑ reduces slightly with substitution and at that time increases, before gradually decreasing to the lowest value, which may be due to ce3+ ion discrimination at grain boundaries (chandrasekaran, selvanandan, & manivannane, 2004). while the lattice constant c found increase, as the concentration of ce+3 increases. after (x = 0.5) it decreases till to (x = 0.75), than again rises to the highest value, which is due to ce3+ ion resemblance at grain boundaries (chandrasekaran et al., 2004). the lattice constant c is found to be between 23.13 – 23.42 å. the variation in lattice constants ɑ and c with respect to ce+3 concentration is shown in (figure 4). the formula (2) is used to calculate the x-ray density x of the prepared nanoparticles: 𝝆𝒙 = 𝟐𝑴/𝑵𝑨𝑽 (2) where, m is the molecular weight (g/mol), na would be the avogadro number (6.023×1023 mol-1), and v seems to be the volume of an individual cells. the x-ray density is observed increasing from 5.29 – 5.76 g/cm3 depending on the ce+3 concentration. which is attributed due to higher molar mass of ce3+ (140.12 g/m) in a comparison with fe3+ (55.845 g/m), so the x-ray density rises as the concentration of ce3+ increases (brightlin & balamurugan, 2016). zaheer abbas gilani, awais ahmed, h. m. noor ul huda khan asghar, muhammad khalid 63 figure 4: variation in lattice constants ɑ and c as a function of ce+3 concentration (x) of bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles figure 5: x-ray density x and bulk densityb as a function of ce+3 concentration (x) of bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles the bulk densityb of the organized pallets is measured by using the principle (3): 𝝆𝒃 = 𝒎𝒃/𝒓 𝟐𝒉 (3) wherever, ‘mb’ is the mass of the pellets, ‘r’ is radius, and ‘h’ is height. bulk density is dependent on the molar mass of the doping element ce+3 (140.12 g/m) and the increasing concentration (x = 0.0, 0.25, 0.5, 0.75, and 1.0). bulk density is observed increases from 1.45 – 1.52 g/cm3 as the concentration of ce+3 increase. x-ray density is found to be higher than bulk density due to the creation of pores during sample preparation and annealing. x-ray density and bulk density with respect to ce+3 concentration is shown in (figure 5). the volume of the unit cell v is calculated by using the formula (4): 𝑽 = √𝟑 𝟐 𝒂𝟐𝒄 (4) where ɑ and c are the lattice constants. the cell volume values of cerium substituted barium hexaferrites bacexfe12-xo19 nano particles at (x = 0.0, 0.25, 0.5, 0.75, and 1.0) is given in the (table 2). the unit cell volume varies with different ce+3 concentration, while at (x = 0.5) cell volume reaches to highest value. the cell volume is found to be in a range 688.35 – 701.61 å3. the formula (5) is used to measure the stacking fault sf of the prepared nanoparticles: journal of materials and physical sciences 1(2), 2020 64 𝐒𝐭𝐚𝐜𝐤𝐢𝐧𝐠 𝐅𝐚𝐮𝐥𝐭 (𝐒𝐅) = 𝟐𝛑𝟐/𝟒𝟓√𝟑(𝐭𝐚𝐧 𝛉) (5) stacking fault is a planner defect and has a direct relation with 2 and has inverse relation with . of stacking fault with respect to ce+3 concentration shows inhomogeneous behavior, where stacking fault first rises then decreases to lowest value and then again increases at (x = 1.0), this inhomogeneous behavior can be due to annealing temperature (brightlin & balamurugan, 2016). stacking fault is found to be between 0.469 – 0.473. variation in cell volume å3 and stacking fault with respect to ce+3 concentration is shown in (figure 6). values of xrd parameters (lattice constants ɑ and c, x-ray density x, bulk density b, cell volume (å3) and stacking fault) with respect to ce+3 concentration (x = 0.0, 0.25, 0.5, 0.75, and 1.0) are given in the (table 2). figure 6: variation in cell volume å3 and stacking fault as a function of ce+3 concentration (x) of bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles table 2 structural parameters: lattice constants ɑ and c, x-ray density x, bulk density b, cell volume (å3), stacking fault of cerium substituted barium hexaferrites bacexfe12-xo19 nanoparticles at (x = 0.0, 0.25. 0.5, 0.75, and 1.0) parameters x = 0.0 x = 0.25 x = 0.5 x = 0.75 x = 1.0 lattice constant ɑ (å) 5.89 5.88 5.89 5.88 5.82 lattice constant c (å) 23.13 23.19 23.33 23.27 23.42 χ-ray density x (g / cm 3) 5.29 5.40 5.46 5.58 5.76 bulk density b (g / cm 3) 1.45 1.48 1.50 1.51 1.52 cell volume (å3) 696 696 701 697 688 stacking fault 0.471 0.473 0.471 0.469 0.470 3.2. crystalline size and strain the crystalline size of bacexfe12-xo19 nanoparticle have been calculated using the debye scherer method, williamson-hall (w-h) method and size-strain plot (ssp) method, which provides better understanding about crystallite size and lattice strain contributions (tetiana tatarchuk et al., 2020). using debye scherrer equation (6), the crystallite size d of ce+3 doped bacexfe12xo19 particles was calculated from the sharpest and strongest peak at (107) hkl of x-ray diffraction patterns (mozaffari, amighian, & darsheshdar, 2014). debye scherrer: 𝑫 = 𝒌/(𝜷 𝒄𝒐𝒔𝜽 ) (6) the constant is denoted by k with a value of 0.89, and the wavelength of the x-ray beam is denoted by  with a value of 1.54 å.  is the full width at half maximum (fwhm) at hkl (107) and the angle of diffraction is denoted by  . the crystalline size was found to be in a range between 16 – 35 nm is shown in (figure 7). this crystallite size is observed smaller as compared to the other reported rare earth doped barium ferrites. as per bragg’s zaheer abbas gilani, awais ahmed, h. m. noor ul huda khan asghar, muhammad khalid 65 law the crystalline size has direct relation with 2 and inverse relation with . the crystalline size varies in a similar way with the substitution of ce3+ contents. this inhomogeneous behavior may be larger ionic radius of ce+3 ion (1.034 å) which was replaced by small ionic radius of fe3+ ions (0.64 å) on the octahedral sites (gilani, warsi, anjum, et al., 2015). the smallest crystalline size is observed 16 nm at (x = 0.75) due to  of the intense peak. the stokes-wilson equation (reddy, babu, reddy, & shim, 2018) is used to calculate the lattice strain l of the prepared nanoparticles: 𝜺𝑳 = 𝜷𝒉𝒌𝒍/𝟒 𝒕𝒂𝒏 𝜽 (𝟏𝟎) −𝟑 (7) figure 7: variation in crystalline size d by debye scherrer (sm) method, microstrain  and dislocation density  as a function of ce+3 concentration (x) of bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles where,  is the full width half maximum (fwhm) of the intense peaks. the microstrain m of prepared nanoparticles is calculated from the equation (8): 𝜺𝑴 = (𝜷 ∗ 𝒄𝒐𝒔 𝜽)/ 𝟒(𝟏𝟎)−𝟑 (8) lattice strain is the disturbance of lattice constants, such as lattice dislocations, which arise from crystal imperfection, while microstrain is the root mean square of variations in the lattice parameters across samples. lattice strain and microstrain has direct relation with  (crystalline size) and inverse relation with 2 . the lattice strain is observed between 3.50 – 7.65 x 10-3, while microstrain is found between 0.96–2.13 x 10-3 (lines−2/m−4). in (figure 7) it is estimated that the microstrain is slightly declining at first, then gradually increasing at the peak stage and then decreasing again. the maximum value of microstrain is observed at (x = 0.75), which indicates that the crystalline size is minimum and 2 is maximum at that point. dislocation density of the prepared nanoparticles is calculated by using the formula: 𝜹 = 𝟏 /𝑫𝟐 (9) the crystalline scale is denoted by d. dislocation density also has inverse relation with crystalline size. the density of dislocations is found to be between 0.79 – 3.88 x 1015 (lines / m2). it is discovered that first it decreases to lowest value than rises in proportion to the substituent concentration. at (x = 0.75), the maximal value of dislocation density is found, which shows the crystalline size d is minimum at that point. the variation in crystalline size d by debye scherrer (sm), microstrain  and dislocation density  as a function of ce+3 concentration is shown in (figure 7). journal of materials and physical sciences 1(2), 2020 66 the crystalline size is also estimated by using williamson–hall method (kumar & kar, 2016). in the w–h technique, the line broadening attributable to the finite size of the coherent scattering region and the internal stress in the prepared film are also taken into account. the diffraction line widening, according to williamson and hall, is caused by crystallite size and strain contribution. the w–h approach is a basic method that uses the peak width as a function of 2 to distinguish between size-induced and strain-induced peak broadening (bindu & thomas, 2014). according to williamson–hall (w–h) method, the sum of the contributions of crystallite size and strain present in the material is the overall peak broadening, which can be stated as (10): (biju, sugathan, vrinda, & salini, 2008). 𝜷𝒉𝒌𝒍 = 𝜷𝑫 + 𝜷𝜺 (10) where, d is the contribution of crystalline size using equation (6), while  is the strain induced, due to crystal imperfection and distortion using equation (bindu & thomas, 2014). the sum of equations (6) and (bindu & thomas, 2014) is given as (11): 𝜷𝒉𝒌𝒍 = 𝒌 𝜷𝒄𝒐𝒔𝜽 + 𝟒 𝜺 𝒕𝒂𝒏𝜽 (11) rearranging the equation (11) we get equation (12): 𝜷𝒉𝒌𝒍𝒄𝒐𝒔𝜽𝒉𝒌𝒍 = 𝒌 𝑫𝑾𝑯 + 𝟒 𝜺 𝒔𝒊𝒏𝜽𝒉𝒌𝒍 (12) where,  is microstrain, which was estimated from slope of the linear fit, while dwh is the crystalline size estimated from the y-intercept (k/dwh). the liner graph is plotted between hkl cos vs 4sinjkl. using williamson–hall method the crystalline size is found to be between 19–68 nm and the correlation coefficient is (r2 = 1.00) for all the samples. the plot of williamson-hall (w-h) method of ce+3 substituted bacexfe12-xo19 at (x = 0.0, 0.25, 0.5, 0.75, 1.0) is shown in (figure 8), and the values of crystalline size dw-h and microstrain m is given in (table 3). figure 8: plot of hkl cos versus 4sinhkl of ce+3 substituted bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles by williamson–hall (w–h) method as per w–h plots, the line broadening was almost isotropic, this emphasizes that the diffracting domains were isotropic, which is attributed due to the contribution of microstrain. in the case of isotropic line broadening, an average size–strain plot (ssp) can be used to provide a better estimate of the size–strain parameters.(bindu & thomas, 2014) zaheer abbas gilani, awais ahmed, h. m. noor ul huda khan asghar, muhammad khalid 67 this approach has the advantage of giving less importance to data from high-angle reflections, where accuracy is often less. in this method, profile corresponding to crystallite size is explained by a lorentz function and the profile corresponding to strain is explained by a gaussian function (tetiana tatarchuk et al., 2017; zak, majid, abrishami, & yousefi, 2011) and is given by (13): (𝒅𝒉𝒌𝒍 × 𝜷𝒉𝒌𝒍 × 𝐜𝐨𝐬 𝜽) 𝟐 = 𝒌 𝑫𝑺𝑺𝑷 × (𝒅𝒉𝒌𝒍 𝟐 × 𝜷𝒉𝒌𝒍 × 𝐜𝐨𝐬 𝜽) + 𝜺𝟐 𝟒 (13) where dhkl is the interplanar spacing, the distance between (hkl) planes, k is constant having a value of 0.89 and  is 0.15406 (nm). dssp is the apparent volume weighted average crystalline size and  is the apparent strain. the liner graph is plotted between (dhkl hkl coshkl)2 on y-axis and (dhkl2 hkl coshkl) on x-axis. figure 9: plot of (dhklhkl cos hkl)2 versus dhkl2hkl coshkl of ce+3 substituted bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles by size–strain plot (ssp) method all the peaks of bacexfe12-xo19 hexagonal ferrites are under 2 = 20 – 80. the average crystalline size was estimated from the slop of the liner fit and the strain  is estimated from the intercept respectively. it is observed that crystalline size is decreasing with increasing ce+3 concentration. the value of crystalline size varying in the range 24– 62 nm and the correlation coefficient varies in the range of (r2 = 0.50797–0.99026). the sizestrain plot (ssp) method of ce+3 substituted bacexfe12-xo19 is shown in (figure 9). the crystalline size obtained from scherrer method is smaller than compare to w–h method and ssp method. the smallest crystalline size obtained from scherrer method is 16 nm, while in w–h method the smallest crystalline size is 19 nm, and 24 in ssp method. however, the average crystalline sizes in ssp method are the most suitable one compared to w–h method. the reason behind large crystalline size in w-h and ssp method is due to strain contribution (şelte & özkal, 2019). in debye scherrer method we consider only fwhm of the most intense peak, while in w-h and ssp method we take average crystalline size from all the peaks, which also includes strain contribution. the magnitude of crystallite size in these 3 models is in agreement with the peak intensities obtained from xrd analysis (figure 1). the values of crystalline size dw-h, lattice strain l, microstrain m and dislocation density  of barium hexaferrite bacexfe12-xo19 nanoparticles, calculated via debye scherrer journal of materials and physical sciences 1(2), 2020 68 (sm) method, williamson-hall (w-h) method and size-strain plot (ssp) method is given in (table 3). table 3 crystalline size dw-h, lattice strain l, microstrain m and dislocation density  of barium hexaferrite bacexfe12-xo19 nanoparticles, calculated by debye scherrer (sm) method, williamson-hall (w-h) method and size-strain plot (ssp) method composition sm method w–h method ssp method x (ce+3) dsm,nm l×10 −3 m×10 −3 ×1015 dw-h, nm m×10 −3  dw-h, nm m ×10 −3  x (ce) = 0.0 30 4.08 1.13 1.09 68 6.1 0.0002 50 1.9 0.0004 x (ce) = 0.25 35 3.50 0.96 0.79 50 6.9 0.0004 62 3.2 0.0002 x (ce) = 0.5 30 4.07 1.13 1.09 44 6.1 0.0005 42 2.3 0.0006 x (ce) = 0.75 16 7.65 2.13 3.88 19 -5.7 0.003 24 3.1 0.002 x (ce) = 1.0 26 4.67 1.29 1.43 54 4.6 0.0003 48 3.9 0.0004 3.3. ftir analysis the fourier transform infrared spectrum (ftir) is performed on the is50 ft-ir. ftir is an important instrument used to determine the internal structure of the prepared samples. the prepared ferrites having compositional formula bacexfe12-x o19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) are investigated. ftir spectra of ce+3 substituted bacexfe12-xo19 is seen in the (figure 10), and were recorded in the range of 390 –1000 cm-1. the two absorption bands below 700 cm-1 have been observed in ftir analysis and are assigned as 1 and 2. the high frequency band 1 observed in a span of 500 – 620 cm-1, representing tetrahedral a-site stretching bands and the low frequency band 2 observed in a span of 400– 500 cm-1, representing octahedral b-site stretching bands. these frequency bands represent the characteristic feature of hexagonal structure. the changes in both 1 and 2 is observed. the octahedral and tetrahedral stretching bands are responsible for two absorption bands of hexagonal ferrites (raju & murthy, 2013). intrinsic vibrations at tetrahedral a-sites are responsible for the first absorption band 1, while the intrinsic vibrations at octahedral bsites are responsible for the second absorption band 2 (wang & hu, 2005). the high frequency bands (533.7 cm-1, 534 cm-1, 538 cm-1, 535 cm-1, 534 cm-1) and low frequency bands (411 cm-1, 412.4 cm-1, 410.1 cm-1, 411 cm-1, 412.9 cm-1) are formed because of the fe3+–o2− stretching vibrations at tetrahedral and octahedral site. figure 10: the ir-spectra of ce+3 substituted bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles annealed at 900c zaheer abbas gilani, awais ahmed, h. m. noor ul huda khan asghar, muhammad khalid 69 the values of 1 is greater than those of 2, suggesting that the tetrahedral vibration site is greater than that of the corresponding octahedral sites. this might be because of tetrahedral a-site has a shorter bond length than the octahedral b-site. the variation in tetrahedral 1 and octahedral 2 absorption peaks is due to the variation generated in the grain size and lattice parameters by increasing ce+3 contents, and these changes affect the stretching vibrations of fe3+–o2− due to which the band position may be changed (gilani, warsi, khan, et al., 2015; junaid et al., 2016). the peaks beyond 1000 cm-1 were due to h–o–h stretching vibrations of absorbed water molecules (karimi et al., 2014). the force constant is an important characteristic of chemical bonds in hexagonal structure. according to researcher, (lakhani, pathak, vasoya, & modi, 2011) the force constants octahedral site ko and tetrahedral site kt of the samples are calculated from the v1 and v2 values by using the formulas (14) and (15): 𝑲𝑶 = 𝟎. 𝟗𝟒𝟐𝟏𝟐𝟖𝑴 (𝝂𝟐) 𝟐/ (𝑴 + 𝟑𝟐) (14) 𝑲𝑻 = √𝟐𝑲𝒐𝝂𝟏/𝝂𝟐 (15) where m is the molecular weight, 1 and 2 is frequency bands. the force constants are examined in order to increase the doping concentration, which in-dictates that interionic bonding may be strengthened. it is observed that the force constant ko varies at different concentrations, while the force constant kt is increases up to (x = 0.75) and after that decreases with increasing ce+3 concentration. the bond length is known to be inversely proportional to the force constant. (tr tatarchuk, bououdina, paliychuk, yaremiy, & moklyak, 2017) the relationship between bond lengths and force constants as a function of ce+3 concentration is shown in figure 11(a) and figure 11(b), where bond lengths are taken in nanometers. the bond lengths octahedral b-site (mb-o) and tetrahedral a-site (ma-o) of the prepared particles is determined using the equation (16) (muneer, farrukh, & raza, 2020): 𝒓 = √𝟏𝟕 𝟑 /𝑲 (16) where k is the force constants ko and kt, which are calculated from the equations (14) and (15). the inverse relationship between force constants ko and kt with octahedral (mb-o) and tetrahedral (ma-o) bond lengths are confirmed. therefore, the chemical bond strengths rise as the distance between the atoms is decreases, resulting in an increase in the force constants values. in (table 4) the computed values of force constants ko and kt, bond lengths (mb-o) and (ma-o) are mentioned. figure 11: (a) correlation between octahedral b-site (mb-o) bond length and force constant (ko) as a function of ce+3 concentration (b) correlation between tetrahedral a-site (ma-o) bond length and force constant (kt) as a function of ce+3 concentration journal of materials and physical sciences 1(2), 2020 70 table 4 molecular weights, ir bands, force constants (k and kt), bond lengths (mb-o and ma-o) of cerium substituted barium hexaferrites bacexfe12-xo19 nanoparticles at (x = 0.0, 0.25. 0.5, 0.75, and 1.0) parameters x = 0.0 x = 0.25 x = 0.5 x = 0.75 x = 1.0 molecular weight (gm/mol) 1111.47 1132.54 1153.61 1174.68 1195.75 1 (cm −1) 533.7 534 538 535 534 2 (cm −2) 411 412.4 410.1 411 412.9 ko × 10 5 (dyne/cm2) 1.54691 1.55828 1.54172 1.57955 1.56433 kt × 10 5 (dyne/cm2) 2.84076 2.85353 2.8603 2.90777 2.86114 mb-o (å) 2.22339 2.21787 2.22578 2.20787 2.21499 ma-o (å) 1.81554 1.81283 1.81139 1.80149 1.81122 3.4. dielectric analysis the dielectric properties are one of the important features, especially for ferrites in order to unfold their suitability for high frequency devices applications. these properties depend upon materials composition, method of preparation and cation positions in the unit cell (gilani, warsi, anjum, et al., 2015). the dielectric properties of prepared ferrite samples with the general formula bacexfe12-xo19 at (x = 0.0, 0.25, 0.5, 0.75, and 1.0) are performed at room temperature using an impedance analyzer over a frequency range of 1 mhz – 3 ghz. the dielectric constant, dielectric loss, tangent loss, ac conductivity, the realimaginary impedance, and the real-imaginary modulus of bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) ferrites were investigated. 3.4.1.dielectric constant and dielectric loss the dielectric constant () and dielectric loss () of prepared cerium substituted barium hexaferrites bacexfe12-xo19 nanoparticles are calculated with respect to the frequency of applied field by using the formulas (17) and (18): 𝜺′ = 𝒕 𝝎𝑨𝜺 𝒛 𝒛𝟐+𝒛𝟐 (17) 𝜺′′ = 𝒕 𝝎𝑨𝜺 𝒛 𝒛𝟐+𝒛𝟐 (18) where t represents pallet thickness,  is the angular frequency of the applied ac signal, a represents pallet surface area, and  signifies the permittivity of free space (8.85× 10-12). figure 12: (a) variations in real component of dielectric constant of bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles as a function of frequency (b) variations in imaginary component of dielectric loss of bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles as a function of frequency zaheer abbas gilani, awais ahmed, h. m. noor ul huda khan asghar, muhammad khalid 71 the dielectric constant as a function of frequency is shown in figure 12(a). the observations revealed that the dielectric constant is decreasing by increasing frequency up to 1 ghz. after 1 ghz, most of compositions increases by increasing frequency. the decrease in dielectric constant is attributed due to dispersion phenomenon. which occurs due to changes in polarization as a function of applied field at low frequency. however, such behavior is not observed at high frequency. these ferrites exhibit such behavior due to maxwell wagner interfacial polarization and koop's phenomenological theory (redinz, 2011). these phenomenon’s states that grains are more effective by high frequencies and grain boundaries have a significant impact on short frequencies, which is due to the space charge effect. at low frequency the electrons are gathered at grain boundaries, so the dielectric constant reaches to highest value. as frequency increases, the dielectric constant decreases, where hopping frequency does not match the functional frequency, so the ferric ions occupy the octahedral site resulting in a ferric ion deficiency, and the dielectric constant is reduced due to the electron exchange between fe3+ and fe2+ (tetiana tatarchuk et al., 2020). ferromagnetic resonance is another name for this phenomenon. after at 2.5 ghz the dielectric constant again increases, since hopping frequency follows the applied field frequency. the highest value of dielectric constant among all the compositions is observed at (x = 0.75) on frequency range of 2.5 ghz. the dielectric loss as a function of frequency is shown in figure 12(b). variations in dielectric loss is observed same like in dielectric constant. almost two relaxation peaks are found in all compositions, lower relaxation peak is found around at 1 ghz, which is due to interfacial or space charge distribution, and the higher relaxation peak is found around 2.5 ghz, which is due to ionic relaxation of ions with multiple valences. some of other variations is also seen with different doping concentrations following hopping phenomenon (m. a. khan et al., 2014). the highest value of dielectric loss is found on (x = 0.75) composition at frequency of 2.5 ghz. the values of dielectric constant () and dielectric loss () from 1 mhz – 3ghz are given in (table 5). 3.4.2.tangent loss and ac conductivity the tangent loss (tan δ) is the rate of energy loss in the dielectric materials. it is related to dielectric constant () and dielectric loss () as per following formula (19): (𝒕𝒂𝒏 𝜹 = 𝜺′′/ 𝜺′) (19) in case of tangent loss, increasing and decreasing at various frequencies are seen. we observed that tangent loss comparatively high at low frequency, which shows electron hopping frequency follows the applied field frequency. but soon at 1 ghz, the tangent loss apparently decreases due to electron hopping between fe2+– fe3+ doesn’t follow the applied field frequency (sheikh et al., 2019). at 1.5 ghz the fifth sample (x = 1.0) in tangent loss reaches to maximum value, and at 2.5 ghz the fourth sample (x = 0.75) reaches to maximum value, where electron hopping frequency following the applied field frequency. these variation in value of tangent loss is explained grain boundaries, impurities and density of samples. according to maxwell–wagner theory tangent loss is inversely proportional with the frequency. from figure 13(a) it is clear that when the frequency increases so the tangent loss decreases and somehow it shows variations (up-down) peaks. the values of tangent loss (tan) from 1 mhz – 3ghz are given in (table 5). one of the most important properties of a dielectric analysis is its alternating current (ac) conductivity, taken in a frequency range of 1 mhz – 3 ghz. the ac conductivity of the prepared cerium doped barium hexaferrites bacexfe12-xo19 nanoparticles at (x = 0.0, 0.25, 0.5, 0.75, and 1.0) is determined. formula (20) is used to calculate the ac conductivity: 𝝈𝒂𝒄 = (𝒕/𝑨). 𝒛′/(𝒛 ′ 𝟐＋𝒛′′ 𝟐 ) (20) where t denotes the width of the pallet, a its area, z real impedance, and z imaginary impedance, respectively. the graph of variances in ac conductivity as a function of frequency for each of prepared samples is shown in figure 13(b). the ac conductivity of the majority of samples has a growing pattern in the low frequency range. soon at high frequency range of 1.5 ghz, it exhibits dispersive behavior, especially at the doping journal of materials and physical sciences 1(2), 2020 72 element (x = 1.0) which shows high dispersion at 1.5 ghz. both the maxwell wagner model and koop's phenomenological theory clarifies that the ferrites materials consist of conducting grains which are separated by resistive layer of grain boundaries (sheikh et al., 2019). figure 13: (a) variations in tangent loss of bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles as a function of frequency (b) variations in alternating current (ac) conductivity of bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles as a function of frequency the conduction and dielectric polarization process are related to each other, so the actions of all samples tend to be planar and constant at low frequencies. the conductivity of fe2+ and fe3+ at octahedral sites is increased at high frequencies due to the properties of grains and hopping phenomena. the loss in porosity may also be behind the increase in conductivity. at low frequencies it is seen that the conductivity has a grain boundary effect whereas in the high frequency range the conducting effects of grains are observed, resulting in a dispersion pattern (farid, ahmad, murtaza, ali, & ahmad, 2016; gilani, warsi, anjum, et al., 2015; junaid et al., 2016). the values of ac conductivity (c) from 1 mhz –3 ghz are given in the (table 5). table 5 measured values of dielectric constant (), dielectric loss () tangent loss (tan δ) and ac conductivity (ac) of cerium substituted barium hexaferrites bacexfe12-xo19 nanoparticles at (x = 0.0, 0.25, 0.5, 0.75, and 1.0) in the frequency range from 1 mhz – 3 ghz parameters frequency x = 0.0 x = 0.25 x = 0.5 x = 0.75 x = 1.0 () 1 mhz 12.95 7.06 10.21 12.85 7.46 1 ghz 9.87 5.45 7.45 9.79 7.63 2.5 ghz 9.19 5.25 7.24 11.48 7.4 3 ghz 9.1 5.38 6.83 8.33 6.97 () 1 mhz 0.29 0.21 0.08 0.99 0.47 1 ghz 1.4 0.78 0.77 0.1 0.34 2.5 ghz 0.28 0.96 0.53 4.89 0.67 3 ghz 0.88 0.56 0.43 0.96 0.21 (tan δ) 1 mhz 0.03 0.01 0.01 0.09 0.04 1 ghz 0.14 0.09 0.08 0.01 0.03 2.5 ghz 0.03 0.14 0.05 0.43 0.07 3 ghz 0.09 0.06 0.06 0.11 0.02 c (s/cm) 1 mhz 8.2e-07 8.9e-06 6.4e-06 3.8e-06 4.6e-06 1 ghz 0.011 0.0065 0.0054 0.0055 0.0039 2.5 ghz 0.0023 0.0386 0.0019 0.0868 0.0092 3 ghz 0.029 0.019 0.023 0.045 0.014 3.4.3.the real and imaginary impedance impedance analysis is a valuable method for measuring the interaction between dielectric properties and microstructural structure of synthesized materials. for each of the ferrite bacexfe12-xo19 at (x = 0.0, 0.25, 0.5, 0.75, and 1.0), the real and imaginary zaheer abbas gilani, awais ahmed, h. m. noor ul huda khan asghar, muhammad khalid 73 impedance are measured in a range of 1 mhz – 3 ghz. real and imaginary parts of impedance are calculated by the formulas (21) and (22): 𝒁′ = 𝑹 = |𝒁| 𝒄𝒐𝒔 𝜽𝒛 (21) 𝒁′′ = 𝑿 = |𝒁| 𝒔𝒊𝒏 𝜽𝒛 (22) where z is real impedance, while z is imaginary impedance. impedance spectrum shows that the increase of applied frequency reduces the real and imaginary impedance parts as seen in figure 14(a) and figure 14(b). these impedance parts are highly depending on the applied field frequency. the impedance curves of all samples (real and imaginary) converged as the frequency increases. at high frequencies, impedance curves of real impedance z and imaginary impedance z merge with each other and shows constant behavior, which is attributed to the release of space charges (joshi, kanchan, joshi, jethva, & parikh, 2017). these space charges are formed as a result of the concentration difference as well as the inhomogeneity of the applied field, which causes these charges to accrue on grain boundaries. with the increase of field frequency, the real and imaginary impedance decreases, indicating that conductivity improves (joshi et al., 2017). the values of real and imaginary impedance from 1 mhz – 3ghz are given in (table 6). figure 14: (a) real part of impedance of bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles as a function of log of frequency (b) imaginary part of impedance of bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) nanoparticles as a function of log of frequency 3.4.4.the real and imaginary modulus the function of grains and grain boundaries by a specified frequency range is investigated using modulus properties. the real and imaginary modulus of the prepared hexagonal ferrite with the composition formula as per a function of functional frequency bacexfe12-xo19 (x = 0.0, 0.25, 0.5, 0.75, and 1.0) was determined. this property can be used to study the frequency dependent interfacial polarization effects, conduction, and relaxation behavior of hexagonal ferrites. the real and imaginary electric modulus are calculated using the following relationships (23) and (24): 𝑴′ = 𝜺′ / (𝜺′ 𝟐 + 𝜺′′ 𝟐 ) (23) 𝑴′′ = 𝜺′′ / (𝜺′ 𝟐 + 𝜺′′ 𝟐 ) (24) where m is real electric modulus and m is imaginary electric modulus. the variations in these parameters m and m for all composition as a function of frequency is shown in figure 15(a) and figure 15(b). the variation in m and m peaks is found due to the occurrence of relaxation phenomenon (frequency dependent variation in conductivity) (j. k. khan et al., 2020). the function of the conductive grain and low conducting grain boundaries shifts as the strength of the applied field changes, which increase of fe2+ and fe3+ hopping. as a result, it is critical to understand the conduction process, whether it is caused by the grain or the grain boundary. journal of materials and physical sciences 1(2), 2020 74 figure 15: (a) variation in real electric modulus as a function of frequency (b) variation in imaginary electric modulus as a function of frequency the magnitude of real modulus is high at low frequencies and is constant up to between 1.5 – 2 ghz. after 2 ghz it gradually decreases in dispersion with increasing frequency till to 2.5 ghz, except at (x = 0.25), where it increases to its highest value at 1 ghz. in the conduction mechanism, this reflects charge carrier mobility over a limited distance, which related to a loss of restoring power and responsible for charge carrier mobility in the occurrence of an induced electric field. this property specifies that electrode polarization has a negligible effect on the material, (costa, pires jr, terezo, graca, & sombra, 2011) which are not much applied on (x = 0.25). the values of real and imaginary electric modulus from 1 mhz – 3 ghz are given in the (table 6). table 6 measured values of real (z) and imaginary (z), real (m) and imaginary (m) of cerium substituted barium hexaferrites bacexfe12-xo19 nanoparticles at (x = 0.0, 0.25, 0.5, 0.75, and 1.0) in the frequency range of 1 mhz – 3 ghz parameters frequency x = 0.0 x = 0.25 x = 0.5 x = 0.75 x = 1.0 z () 1 mhz 384 6000 3010 1740 2290 1 ghz 4.44 3.66 2.62 2.36 1.78 2.5 ghz 0.145 3.6 0.109 6.39 0.708 3 ghz 1.84 1.58 1.48 2.65 0.76 z () 1 mhz 78700 94000 78500 77900 80900 1 ghz 73.7 85.6 75.3 78.2 0.03 2.5 ghz 28.9 34.9 27.4 30.5 31.9 3 ghz 28.6 32.4 28.8 27.7 27 m 1 mhz 0.33 0.39 0.33 0.33 0.34 1 ghz 0.311 0.362 0.331 0.312 0.33 2.5 ghz 0.31 0.37 0.29 0.32 0.34 3 ghz 0.36 0.4 0.37 0.35 0.34 m 1 mhz 0.0012 0.023 0.013 0.0073 0.0097 1 ghz 0.012 0.012 0.012 0.0099 0.0075 2.5 ghz 0.0015 0.032 0.0011 0.062 0.0074 3 ghz 0.023 0.012 0.012 0.033 0.0091 4. conclusions the cerium (ce+3) substituted barium hexaferrite (bacexfe12-xo19) nanoparticles were successfully synthesized with various ce+3 concentrations (x = 0.0, 0.25, 0.5, 0.75, and 1.0) by using the sol-gel auto combustion method and were investigated by various techniques such as xrd, ftir and dielectric measurements in order to determine their structural, internal and electric properties. the formation of ce3+ substituted bacexfe12-xo19 and the hexagonal structure has been confirmed with the help of xrd patterns by using rietveld refinement. the refined patterns show that at 2θ = 32°, very extreme peaks with (107) hkl formed, which is found to be the perfect peak for hexaferrite nanoparticles. no impurity phase is detected. the measured grain size for each sample has shown correlations with xrd results, indicating that the prepared samples are crystalline. crystalline size is calculated by debye scherrer method, w–h method and ssp method. the smallest crystalline size is found 16 nm by debye scherrer equation. lattice constant ɑ is zaheer abbas gilani, awais ahmed, h. m. noor ul huda khan asghar, muhammad khalid 75 found to decrease, due to the octahedral site replacing a broad radius of ce3+ ion (1.034) with a smaller radius of fe3+ ion (0.64), while lattice constant c found increases. fourier transform infrared spectroscopy (ftir) studies shows the structural changes and chemical effects. the ir-spectra of bacexfe12-xo19 with different ce+3 concentrations, the two stretching bands tetrahedral and octahedral sites were observed between 400 – 620 cm-1, which exhibited the characteristic features of hexagonal structure, confirming the formation of hexaferrite nano particles. the dielectric studies are carried out in a frequency range from 1 mhz – 3 ghz, following the maxwell wagner model. the ac conductivity of all the samples is low at low frequency range. however, in the high frequency range it exhibits dispersive behavior which shows the conductivity improves. such behavior is due to the grain effect at high frequency. the real and imaginary impedance were high at low frequency, as soon frequency increases impedance decreases to the lowest value and shows constant behavior, which is attributed to the release of space charges. the real and imaginary modulus analysis conducted to the understand of the grain and grain boundary effect. the variation in m and m is due to the occurrence of relaxation phenomenon. these dielectric properties can be utilized in high frequency devices, microwave technologies, high storage devices, and semiconductor devices. acknowledgements we appreciate the assistance, funds, and facilities provided by the oric of baluchistan university of information technology, engineering, and management sciences (buitems), quetta, pakistan, university of karachi, sindh, pakistan, and the institute of physics, the islamia university of bahawalpur, punjab, pakistan, in completing this research work in the department of physics. references al-hilli, m. f., li, s., & kassim, k. s. 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(2011). x-ray analysis of zno nanoparticles by williamson–hall and size–strain plot methods. solid state sciences, 13(1), 251-256. https://doi.org/10.1016/j.ceramint.2018.01.123 https://doi.org/10.52131/jmps.2022.0301.0021 1 journal of materials and physical sciences volume 3, number 1, 2022, pages 01 13 journal homepage: https://journals.internationalrasd.org/index.php/jmps tuning the properties of praseodymium cobalt-zinc ferrites by substitution of bismuth ruba akbar1, muhammad shahzad shifa2*, aamir saleem2, aurang zaib2, faseeh ur raheem2, muhammad waqas khaliq3* 1 department of physics, government college university, faisalabad, pakistan 2 institute of physics, the islamia university of bahawalpur, bahawalpur, 63100, pakistan 2 alba synchrotron light source, carrer de la llum, 2, 26, 08290 cerdanyola del vallès, barcelona, spain article info abstract article history: received: january 20, 2022 revised: march 19, 2022 accepted: june 28, 2022 available online: june 29, 2022 this work carried out the study of co0.5zn0.5bi0.4-xpr0.1fe1.5+xo4 spinel ferrite series (x = 0,0.1, 0.2, 0.3 and 0.4) prepared via micro-emulsion route. effects on structural, electrical, optical and morphology properties is studied by varying bi concentration (x = 0,0.1, 0.2, 0.3 and 0.4). the characterization techniques employed included x-ray diffraction (xrd), scanning electron microscope (sem), uvvisible spectroscopy and fourier transform infrared spectroscopy (ftir). xrd results confirmed the spinel structure having lattice parameter around 8.39 å and particle size decreased from 30 nm to 41 nm with increasing bi concentration. fourier transform infrared spectroscopy (ftir) revealed fingerprints of metal oxides band at 408-577 cm-1. optical properties were studied uv-visible spectroscopy and eg was found to vary from 2.83 ev to 2.59 ev. the scanning electron microscope (sem) described the morphology of the samples. we then examine the results and the material's characteristics, as well as the areas in which it can be used. keywords: bismuth ferrite x-ray diffraction scanning electron microscope uv-visible spectroscopy fourier transform ir spectroscopy © 2022 the authors, published by irasd. this is an open access article under the creative common attribution non-commercial 4.0 *corresponding authors’ email: shahzad.shifa@iub.edu.pk, mkhaliq@cells.es 1. introduction spinel ferrites are the most researched ferrimagnetic materials which are finding its applications in emerging material sciences. (batoo et al., 2022) these ferrites have cubic fcc structure having at least a divalent meal ion in addition to iron oxide. the metal ion is replaced by combinations of two or more different ions to optimize the ferrite’s structure in order to obtain the desired properties. (velhal, patil, shelke, deshpande, & puri, 2015) cobalt is progressively reported to increase the magnetic properties of soft spinel ferrites due its magnetic nature and light weight. (almuhamady & aboulfotoh, 2012) cobalt’s higher cost hinders its substitution in larger amounts in ferrites. to circumvent this problem and for a cost-effective preparation it is wise to try a combination of this element with another divalent metal ion. zinc is another divalent metal atom but it does not affect the magnetic properties due to its diamagnetic nature. (velhal et al., 2015) however combination of cobalt and zinc is very promising and it is finding numerous applications in fast switching (batoo, 2011) and electromagnetic interference (emi) shielding devices. (gorbachev et al., 2020) the magnetic properties of co-zn ferrites can be enhanced and engineered by the introduction of rare-earth ions into the interstitial sites. these rare-earth ions when placed in the spinel lattice alters structural, electrical, and magnetic properties because of interactions arising between rare-earth and iron ions. (almuhamady & aboulfotoh, 2012) praseodymium substituted co-zn ferrites have been reported using ceramic method (farid et al., 2017). https://journals.internationalrasd.org/index.php/jmps mailto:shahzad.shifa@iub.edu.pk mailto:mkhaliq@cells.es journal of materials and physical sciences 3(1), 2022 2 bismuth bi is a diamagnetic element but its doping in the co-zn ferrites is reported to yield a promising emi shielding material (batoo et al., 2022). it is because of the fact that incorporation of the bi in place of iron ion changes the saturation magnetization and improvement in electrical properties. (sharif et al., 2019). moreover, bi also modify the structural, magnetic and dielectric properties (routray, sanyal, & behera, 2017) there are no studies available on the bi and pr doped co-zn spinel ferrites. among many wet chemical methods micro-emulsion method is not only simple and economical, but it also gives control and uniformity over particle size. resulting nanocrystals greatly help in the study of properties of spinel ferrites (gilani & shifa, 2018). the spinel ferrites are used to address several of these issues in the same way as cobalt zinc ferrite (aubert, loyau, mazaleyrat, & lobue, 2017). there is an abundance of bismuth, cobalt, and zinc. most zinc is found in minerals. because they are inexpensive, cobalt, zinc, and bismuth may be employed widely and easily. regarding these techniques, the practical handling of nanoparticles depends on a variety of factors, including particle size and cation dispersion in the spinel's tetrahedral (a) and octahedral (b) sites (bharathi & sankar, 2018). ferrites also exhibit good dielectric qualities without exhibiting electricity the morally repugnant dielectric features that allow electromagnetic brines to travel through them. this phenomenon does not arise in the deep earth. only the ferrites that resemble crystals exhibit dielectric characteristics (tholkappiyan & vishista, 2015). additionally, it has been deduced from the literature that bi substitution can alter the structural, magnetic, and dielectric properties of ferrites (routray et al., 2017). the effect of bi2+ substitution on the electrical characteristics of praseodymium cobalt zinc ferrites is explored in this paper. utilizing the micro-emulsion technique, samples are prepared. to fulfil the device's integration requirements, the macroemulsion has become crucial. we intended to verify that there is no evidence of the influence of bi2+ doping on co0.5zn0.5bi0.4-xpr0.1fe1.5+xo4 at various variations of x = 0.0, 0.1, 0.2, and 0.3 to create a nanoparticle. it is extremely effective to add the right additive to increase or improve the grain size in order to produce bi2+ doping on co0.5zn0.5bi0.4-xpr0.1fe1.5+xo4 ceramics with low coercivity and high saturation magnetization at temperature. the work that followed was clearly directed at morphological analysis. ironstone spinel ferrites still include magnetic iron oxide due to their varied characteristics and usage. co0.5zn0.5bi0.4-xpr0.1fe1.5+xo4 of the nano-ferrites were examined for their physical properties using several characterization techniques, including x-ray diffraction (xrd), fourier transformation of infrared spectroscopy (ftir), uv-visible, and scanning electron microscopy (sem) (scanning electron microscope). the information on the morphology and structure of nano-ferrites was then confirmed by sem and xrd. the spinel ferrite's cubic single-phase structure was formed, according to the xrd pattern. the analysis of samples using x-rays was carried out to investigate the structural change that occurred in the samples as a result of the dopant. the morphology is confirmed using a scanning electron microscope. the fourier transformation verifies how much of each wavelength is absorbed by the sample. the same information can be expressed naturally by fourier transformation spectroscopy. the end result of this work helps to produce a material with enhanced features. in this paper, we report the synthesis of co0.5zn0.5bi0.4−xpr0.1fe1.5+xo4 spinel ferrite prepared via micro-emulsion method while taking different bi concentration (x = 0,0.1, 0.2, 0.3 and 0.4). effects on structural, electrical, optical and morphology properties also studied with the help of different characterization techniques such as x-ray diffraction (xrd), scanning electron microscope (sem), uv-visible spectroscopy and fourier transform infrared spectroscopy (ftir). 2. experimental procedures the bi replacement co0.5zn0.5bi0.4−xpr0.1fe1.5+xo4 is made through micro-emulsion. this series is constructed using the elements below. it uses ferric nitrate nonahydrate, whose chemical formula is fe (no3)3.9h2o. iron nitrate molar mass 404 g/mol, (acs≥98%) utilized is bismuth nitrate pentahydrate, whose chemical formula is bi (no3)3.9h2o. molecular weight 485.07 g/mol (99 percent sigma-aldrich). hexahydrate of praseodymium ruba akbar, muhammad shahzad shifa, aamir saleem, aurang zaib, faseeh ur raheem, muhammad waqas khaliq 3 nitrate 𝑁2𝑂2pr.6h2o it uses zinc nitrate hexahydrate, with a molecular weight of 297.49 g/mol (98% sigma-aldrich) hexahydrate of cobalt nitrate. co (no3)3.6h2o is the chemical reagent's formula. molar-mass 291.03 g/mol (98% sigma-aldrich) 208.98 g/mol of bismuth (99% sigma-aldrich) acetyl-trimethyl-ammonium bromide (ctab), molar mass = 364.45 g/mol on a magnetic hot plate set to a temperature of 55 to 60 0c, the fixed volumes of a solution of metal salts with a concentration of 0.15m were combined and agitated. aqueous ctab solution (100ml, 0.45m) was then employed as the surfactant. the ph was then adjusted using naoh, and it was kept between 11 and 12 throughout the entire solution. the reaction mixture was stirred for an additional 4-5 hours. as the reaction mixture changed into participants, they were cleaned with deionized water until the ph reached 7. the sample was placed in the oven for drying, where water was converted to vapors at a temperature of 1000c while the components were ground. then, annealing was done in a temperature-controlled muffle furnace, the vulcan a-550, for 7 hours at 700 0c, heating at a rate of 15 0c/min. the annealed materials were ground into a powder and evaluated using a variety of methods. the philips 'x'pert pro 3040/60 diffract meter with cu k as the radiation source was used to conduct the powder xrd analysis to learn more about the purity of the synthesized materials. perkin elmer spectrometer was used to see the ft-ir spectra in the case of ftir spectra. to examine the same at room temperature, uv-visible spectroscopy was performed. using a scanning electron microscope from japan (sm-6590 lv), the morphology of powders was examined. 3. results and discussion 3.1. ftir (fourier transform infrared spectroscopy analysis) in 1957, the first reasonably priced spectrometer was able to video record an infrared spectrum (chaimovich, vaughan, & westheimer, 1968). the wavelength range that this device covers is 2.5 m to 15 m. a fundamental molecular vibration's highest termed vibration frequency was chosen to fall within the minor wavelength perimeter (mekebri, blondina, & crane, 2009). the fact that the dispersing element was a prism made from a rock-salt crystal that was ready to solidify at wavelengths higher than around 15 μm a spectral area that came to be known as the rock-salt region made the higher limit necessary. later devices increased the range to 25 μm (400 cm-1) using potassium bromide prisms (connes & connes, 1966). the far-infrared zone, which begins at a wavelength of 50 μm (200 cm-1), was first recognized. at longer wavelengths, it transforms into the microwave region. the ftir apparent bands support the praseodymium cobalt zinc ferrite's structural integrity. the spinel ferrites' characteristic extensive band in the 550-600 cm-1 (v1) range suggests that metal ions are extending the pulsations to the tetrahedral site, whereas the band at 400450 cm-1 (v2) is similar to the octahedral site. this collection indicates an uneven (no3-) extend vibration to go that the remaining nitrate group since the other weak band to research at a heavy frequency is 1384 cm-1. to demonstrate that the hydroxyl group is responsible for the sample investigation, a thorough band analysis in the range 1642-3430 cm-1 was initiated. the c-h group is to be stretched inside the other range of 2845-2923 cm-1 (bartick, 2002). in the range of 500 to 4000 c/m, the ftir spectrum can reveal a lot about the structure and bonding. if there is moisture in the sample and there is no absorption spectra at the wavelengths above 1250 c/m, ftir will also show an absorption band above 1250 c/m. due to trapped nitrogen, an ftir spectral band can be seen at 1300 c/m. at 555 c/m and 445 c/m in the annealed, the absorption band becomes prominent. the metal oxygen can be seen in the absorption band value of 408-577 cm-1. nitrate groups are detected in a weak band at 1379 cm-1. it is known that the c-h group is stretching at the absorption band of 2916 cm-1. the hydroxyl group is visible in the peaks near 3417 and 1630. journal of materials and physical sciences 3(1), 2022 4 4000 3500 3000 2500 2000 1500 1000 500 0.980 0.985 0.990 0.995 1.000 1.005 t ra n sm itt a tio n (% ) wave number(cm -1 ) 408 577 1379 3417 1630 2916 co 0.5 zn 0.5 pr 0.1 bi 0.4 fe 1.5 o 4 figure 1: ftir investigation of co0.5zn0.5bi0.4pr0.1fe1.5o4 4000 3500 3000 2500 2000 1500 1000 500 0.975 0.980 0.985 0.990 0.995 1.000 1.005 t ra m it ta n c e (% ) wave number(cm) -1 408 567 13681628 29153419 co 0.5 zn 0.5 pr 0.1 bi 0.3 fe 1.6 o 4 figure 2: ftir investigation of co0.5zn0.5bi0.3pr0.1fe1.6o4 the metal oxygen may be seen in the absorption band value of 408-567 cm-1. nitrates are detected in the weak band at 1368 cm-1. it is known that the c-h group is stretching at the absorption band of 2915 cm-1. the hydroxyl group is visible in the peaks between 3419 and 1628. ruba akbar, muhammad shahzad shifa, aamir saleem, aurang zaib, faseeh ur raheem, muhammad waqas khaliq 5 4000 3500 3000 2500 2000 1500 1000 500 0.92 0.93 0.94 0.95 0.96 0.97 0.98 0.99 1.00 1.01 t ra n m it ta n c e (% ) wave number(cm -1 ) 408 577 1378 1625 29053416 co 0.5 zn 0.5 pr 0.1 bi 0.2 fe 1.7 o 4 figure 3: ftir investigation of co0.5zn0.5bi0.2pr0.1fe1.7o4 the metal oxygen can be seen in the absorption band value of 408-577 cm-1. nitrate groups are detected in a weak band at 1378 cm-1. it is known that the c-h group is stretched in the absorption band at 2905 cm-1. the hydroxyl group is visible in the peaks near 3416 and 1619. 4000 3500 3000 2500 2000 1500 1000 500 0.965 0.970 0.975 0.980 0.985 0.990 0.995 1.000 1.005 t ra n m it ta n c e (% ) wave number(cm -1 ) 408 577 13783411 2910 1619 co 0.5 zn 0.5 pr 0.1 bi 0.1 fe 1.8 o 4 figure 4: ftir investigation of co0.5zn0.5bi0.1pr0.1fe1.8o4 journal of materials and physical sciences 3(1), 2022 6 the metal oxygen can be seen in the absorption band value of 408-577 cm-1. nitrate groups are detected in a weak band at 1378 cm-1. it is known that the c-h group is stretching at the absorption band of 2910 cm-1. the hydroxyl group is visible in the peaks between 3411 and 1619. 3.2. x-ray diffraction analysis this method allows us to investigate interplane, distance, crystal size, and crystal. this method also allows us to investigate the parameters of structural lattices. figures 5 through 8 should show the usual xrd spectra of bi substituted pr co-zn ferrites with various compositions of x = 0.0, 0.1, 0.2, 0.3, and 0.4. we successfully identified the following peaks as being (111), (200), (220), (311), (222), (400), (422), (511), (440), (620), and (533), which are the distinctive planes of single-phase cubic spinel structure (bragg & bragg, 1913) demonstrating the cations' ability to dissolve into the appropriate lattice locations. the crystalline resources can maintain the envoy pattern that continues to be an acceptable source of inquiry in significant sciences by applying x-rays diffracted, or other methods utilizing bragg's law (misra & dubinskii, 2002). below is a formula to calculate the lattice constant. a = 𝜆 2𝑆𝑖𝑛𝜃 √ℎ2 + 𝑘2 + 𝑙2 (1) a is the lattice parameters, d is crystalline size, d is inter plane distance, dx-ray is x-ray density. lattice constant can be find out with other formula a = d √ℎ2 + 𝑘2 + 𝑙2 (2) d = 𝜆 2𝑆𝑖𝑛𝜃 (3) 𝐷 = 𝐾𝜆 𝛽ℎ𝑘𝑙𝐶𝑂𝑆𝜃 (4) 𝑑𝑥−𝑟𝑎𝑦 = 𝑍𝑀 𝑁𝐴𝑉 (5) here, "h," "k," and "l" stand for the miller index of the given plane, and " λ " denotes the x-ray wavelength. the shape factor is denoted by "k," the unit cell volume is "v," the bragg's diffraction angle is " θ " the full width at half maxima to the individual plane is "𝛽ℎ𝑘𝑙 ," the avogadro's number is "na = 6.02 10 23 g/mol," the molecular mass is "m," and the spinel organization's fragments per unit cell is "z." 20 25 30 35 40 45 50 55 60 0 200 400 600 800 o ff s e t y v a lu e s a pr4 pr3 pr2 pr1 (311) (311) (311) (311) (222) (222) (222) (222) 460 460 460 460 (200) (200) (200) (200) (220) (220) (220) (220) (110) (110) (110) (110) figure 5: x-ray diffraction analysis of co0.5zn0.5bi0.4-xpr0.1fe1.5+xo4 ruba akbar, muhammad shahzad shifa, aamir saleem, aurang zaib, faseeh ur raheem, muhammad waqas khaliq 7 table 1 lattice constant, cell volume, bulk density, x-ray density, and porosity and crystalline size of co0.5zn0.5bi0.4-xpr0.1fe1.5+xo4 bi content (x) x=0.0 x= 0.1 x=0.2 x=0.3 lattice constant (å) 8.398 8.396 8.395 8.392 cell volume (å)3 587.07 586.53 585.32 584.69 bulk density (g/cm3) 2.53 2.43 2.29 2.21 x-ray density (g/cm3) 4.85 4.83 4.79 4.76 porosity 0.49 0.53 0.54 0.55 crystalline size (nm) 41.09 39.34 35.69 30.69 bi substituted co-zn ferrites crystallize size less than 20 nm and also decreases with increasing the bi content is reported (batoo et al., 2022). however in our work larger crystallite size is due to pr which has larger ionic radii and replacing smaller fe ion. pr substituted co-zn ferrites crystallize size vary (37.86-50.43) nm, by decreasing pr content is reported (farid et al., 2017). in this study crystallize size is found in range of 30 to 41 nm even though pr and bi both have been substituted and it is pertinent to mention here that a decreases in crystallize size is observed with increasing bi content. 3.3. ultraviolet–visible spectroscopy (uv-vis) to determine how attentive a test is in a solution, uv-vis is a quick, easy, and affordable way. it can be used for relatively basic analyses, anywhere the type of compound to be examined (the "analyte") is well-known to conduct a quantitative investigation to confirm the analyte's concentration. single-beam devices include spectrophotometers. sample removal is used in single beam devices for measurement. this was the original design, and it is still regularly used in classroom settings and in business laboratories. the uv/vis spectrophotometer is the name of the device used in ultravioletvisible spectroscopy (metha, 2012). it gauges the brightness of light passing through a sample. the ready magnetic nanomaterials on the chart were scanned after the uv-visible analysis was finished. the computation was purposefully consumed by band gap energy in the form of the samples co0.4pr0.1zn0.4fe2o4(2.42ev), co0.4pr0.1zn0.4bi0.05fe1.95o4 (2.38 ev), co0.4pr0.1zn0.4bi0.1fe1.90o4 (2.37ev), and co0.4pr0.1zn0.4bi0.15fe1.85o4 (2.32 ev). since the following equation, the k-m (kubelka-munk) model (suzuki, 2002) and f(r) are commonly used to derive the band gap of these samples from the eg quantity. 𝐹(𝑅) = (1−𝑅)2 2𝑅 (6) figure 6: ultraviolet–visible spectroscopy of co0.5zn0.5bi0.3pr0.1fe1.6o4 journal of materials and physical sciences 3(1), 2022 8 figure 7: ultraviolet–visible spectroscopy of co0.5zn0.5bi0.2pr0.1fe1.7o4 1 2 3 4 5 6 7 0 10 20 30 40 50 60 70 (f (r )h ) 2 energy(ev) e g =2.83 ev co 0.5 zn 0.5 bi 0.1 pr 0.1 fr 1.8 o 4 figure 8: ultraviolet–visible spectroscopy of co0.5zn0.5bi0.1pr0.1fe1.8o4 0.00 0.05 0.10 0.15 0.20 0.25 0.30 8.392 8.393 8.394 8.395 8.396 8.397 8.398 l a tt ic e c o n s ta n t a x x = 0.0 x = 0.1 x = 0.2 x = 0.3 figure 9: lattice constant of co0.5zn0.5bi0.4-xpr0.1fe1.5+xo4 ruba akbar, muhammad shahzad shifa, aamir saleem, aurang zaib, faseeh ur raheem, muhammad waqas khaliq 9 0.00 0.05 0.10 0.15 0.20 0.25 0.30 30 32 34 36 38 40 42 x = 0.0 x = 0.1 x = 0.2 x = 0.3 (c ry s ta ll in e s iz e ( n m ) x figure 10: crystalline size of co0.5zn0.5bi0.4-xpr0.1fe1.5+xo4 3.4. scanning electron microscope (sem) the scanning electron microscope (sem) is used to produce a variety of signals at the surface of hard materials using a focused beam of higher-energy electrons (faulkner, akman, bell, jeffree, & oparka, 2008). the signals produced by interactions between electrons and samples reveal details on the sample's exterior shape, crystalline structure, chemical composition, and method of material uptake. in the best applications, data are assembled over a selected region of the model's surface, and a 2-dimensional representation of these attributes' spatial changes is created. the traditional (magnification range 20x to 30,000x) sem techniques can examine areas with widths ranging from around 1 cm to 5 microns (wergin & erbe, 1994). the sem is also unable to conduct studies of selected locations on the sample; this capability is particularly helpful in moulding chemical composition in a qualitative or semi-quantitative manner as well as crystalline structure and crystal orientations. the sem's goal and function are quite similar to those of the epma, and there is a wide range of capabilities shared by the two instruments (barnes, mulvaney, wolff, & robinson, 2002). when electrons accelerate in a sem, significant quantities of kinetic energy are consumed, and this energy degenerates as a variety of signals are produced as a result of interactions between the electrons and the sample, as well as when the incident electrons are slowed down in a hard sample. possibly draining relationship. 𝐷 = 1.5𝐿 𝑀×𝑁 (7) n is the total number of the complete sample, m is the amplification, and l is the overall check line length. the samples' d grain size was abnormal, measuring 41.09 nm. when excited electrons return to lower energy states, they release x-rays with a constant wavelength. as a result, each element in a mineral that the electron beam "excites" emits distinctive x-rays. high-resolution images of the items are created using the sem, which is also utilized to display spatial differences in the chemical composition. the sem is also widely used to study single phases that are based on qualitative chemical analysis and sample crystal structure. the sem can also accurately measure features and objects with a size of 50 nm or smaller (baghaei, 2007). sems equipped with diffracted backscattered electron detection capabilities are used to inspect microfabric. the samples must fit inside the chamber of the microscope and be stable. the largest size in straight dimensions is often between 10 cm and 20 cm, although vertical dimensions are typically much less and almost ever exceed 40 mm. for the majority of devices, samples should be stable in a vacuum between 10-5 and 10-6 torr. samples that could outgase at low pressures should not be tested in typical sems (chandler & roberson, 2009). sems feature a wide variety of sample types that can be tested satisfactorily in these specific instruments. sems miss light journal of materials and physical sciences 3(1), 2022 10 elements like h, he, and li, while many instruments miss elements like na that have atomic numbers below 11. if the device cannot operate in the low vacuum mode, an electrical covering should be helpful to electrically insulate samples for learning about traditional sems (russell & daghlian, 1985). figure 11: sem investigation of sample (co0.5zn0.5bi0.4 pr0.1fe1.5o4) sem provides details on the morphology of sample "1" and displays images at various magnifications. figure 12: sem investigation of sample (co0.5zn0.5bi0.3pr0.1fe1.6o 4) sem provides details on the morphology of sample "2" and displays images at various magnifications. ruba akbar, muhammad shahzad shifa, aamir saleem, aurang zaib, faseeh ur raheem, muhammad waqas khaliq 11 figure 13: sem investigation of sample (co0.5zn0.5bi0.2pr0.1fe1.7o4) sem provides details on the morphology of sample "3" and displays images at various magnifications. figure 14: sem investigation of sample (co0.5zn0.5bi0.1pr0.1fe1.8o4) sem provides details on the morphology of sample "4" and displays images at various magnifications. 4. conclusions we have reported the successful synthesis of co0.5zn0.5bi0.4−xpr0.1fe1.5+xo4 spinel ferrite series with varying bi concentration (x = 0,0.1, 0.2, 0.3 and 0.4) via micro-emulsion method. spinel structure was confirmed by xrd results. effects on structural, electrical, optical and morphology properties is studied by varying bi concentration (x = 0,0.1, 0.2, 0.3 and 0.4). the characterization techniques employed included x-ray diffraction (xrd), fourier transform infrared spectroscopy, scanning electron microscope (sem), and uvvisible spectroscopy (ftir). the spinel structure was verified by xrd measurements to have a lattice parameter of 8.39 å and particle sizes that increased with increasing bi concentrations from 30 to 41 nm. the metal oxides band at 408-577 cm-1 was identified using fourier transform infrared spectroscopy (ftir). decrease in the value of eg was journal of materials and physical sciences 3(1), 2022 12 observed from 2.83 ev to 2.59 ev with increase in the bi content. sem analysis of the samples' morphology provided this information. references almuhamady, a., & aboulfotoh, n. 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