Characterization and Application of Nanomaterials 2025, 8(2), 11330. https://doi.org/10.24294/can11330 1 Article Role of aluminium doping in tailoring the structural, electrical, and magnetic characteristics of Li-Co ferrites using sol-gel auto-combustion synthesis Khushal P. Mudholkar1, Madhu G. Kottad1, Shivanand V. Angadi1, Lingaraj D. Horakeri1, Sushant S. Kakati2, Shridhar N. Mathad2,*, Chidanandayya S. Hiremath3, Rangappa B. Pujar1, Mahesh S. Bannur4 1 Department of Physics, P. C. Jabin Science College, Hubballi 580021, India 2 Department of Engineering Physics, K. L. E. Institute of Technology, Hubballi 580027, India 3 Department of Physics, S. K. Arts and H. S. Kotambari Science Institute, Hubballi 580021, India 4 Department of Physics, A. G. M. Rural College of Engineering and Technology, Varur, Hubballi 581207, India * Corresponding author: Shridhar N. Mathad, physicssiddu@gmail.com, physicssiddu@kleit.ac.in Abstract: This study examined the impact of aluminium doping on the structural, electrical, and magnetic properties of Li(0.5)Co(0.75)AlxFe(2−x)O4 spinel ferrites (x =0.15 to 0.60). The samples were synthesised using the sol-gel auto-combustion technique, and they were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier- transform infrared spectroscopy (FTIR), dielectric measurements, and vibrating sample magnetometry (VSM). All samples possessed a single-phase cubic spinel structure with Fd-3m space group, according to XRD analyses. SEM images showed the creation of homogeneous particles with an average size of about 21 nm. All samples had spinel ferrite phases, confirmed from FTIR spectra. DC electrical conductivity studies showed that the conductivity increased with increasing aluminium content up to x = 0.45 before dropping at x = 0.60. The maximum saturation magnetization value was found at x = 0.45, according to VSM measurements, which demonstrated that the magnetic characteristics were strongly correlated with the amount of aluminium. Keywords: ferrites; structural studies; morphology; magnetic materials 1. Introduction Ferrites are a class of magnetic materials with a wide range of technological applications, including in microwave devices, transformers, and magnetic recording media [1]. Ferrites are typically composed of iron oxide (Fe2O3) and other metal oxides, such as zinc oxide (ZnO) or nickel oxide (NiO). The properties of ferrites can be tailored for specific applications by doping them with various metal ions. Aluminium (Al)-doped lithium cobalt (Li-Co) ferrites are a class of magnetic materials that have gained increasing attention in recent years due to their potential applications in various fields such as microwave absorption [2], magnetic recording [3], and electromagnetic interference (EMI) shielding [4]. These materials are composed of a ferrimagnetic spinel structure with a general formula of LiCo1−xAlxFe2O4, where x represents the Al doping concentration. The Al doping in Li-Co ferrites results in a significant enhancement in the magnetic properties, such as the saturation magnetization and the coercive field, as well as an improvement in the microwave absorption characteristics. The synthesis of Al-doped Li-Co ferrites can be achieved through various CITATION Mudholkar KP, Kottad MG, Angadi SV, et al. Role of aluminium doping in tailoring the structural, electrical, and magnetic characteristics of Li-Co ferrites using sol-gel auto-combustion synthesis. Characterization and Application of Nanomaterials. 2025; 8(2): 11330. https://doi.org/10.24294/can11330 ARTICLE INFO Received: 14 January2025 Accepted: 20 March2025 Available online: 19 May 2025 COPYRIGHT Copyright © 2025 by author(s). Characterization and Application of Nanomaterials is published by EnPress Publisher, LLC. This work is licensed under the Creative Commons Attribution (CC BY) license. https://creativecommons.org/licenses/ by/4.0/ Characterization and Application of Nanomaterials 2025, 8(2), 11330. 2 methods such as solid-state reaction [1], sol-gel[5], the co-precipitation method [6], and hydrothermal synthesis[7]. Among these methods, the solid-state reaction method is the most commonly used due to its simplicity and cost-effectiveness. In this method, the starting materials, such as LiCoO2, CoO, Fe2O3, and Al2O3, are mixed together in a desired proportion and heated at a high temperature for several hours. The final product is then cooled and ground to a fine powder. The magnetic properties of Al- doped Li-Co ferrites are strongly influenced by the Al doping concentration. The saturation magnetization increases with increasing Al doping concentration, reaching a maximum at x = 0.1. This is due to the substitution of Al3+ ions for Co2+ ions in the ferrite structure, which results in a decrease in the average spin state of the Co ions and a corresponding increase in the magnetic moment. The coercive field also increases with increasing Al doping concentration, which indicates an improvement in the magnetic stability of the material [8–12]. In addition to the magnetic properties, Al-doped Li-Co ferrites have been found to have excellent microwave absorption characteristics [9]. The absorption peak of these materials is found to be in the range of 2–18 GHz, making them suitable for use in the microwave frequency range. The absorption performance is also found to improve with increasing Al doping concentration, which is attributed to the enhancement of the magnetic loss caused by the substitution of Al3+ ions for Co2+ ions. The EMI shielding performance of the Al-doped Li-Co ferrites is also found to be good [13]. EMI is the unwanted interference caused by electromagnetic radiation and it is a major concern in many electronic devices. The shielding effectiveness of these materials is found to increase with increasing Al doping concentration, which is attributed to the improvement in the magnetic properties as well as the increase in the electrical conductivity caused by the substitution of Al3+ ions for Co2+ions.Furthermore, the Al- doping in Li-Co ferrites is found to affect the microstructure of the materials. The Al- doping leads to the formation of smaller grain size and more homogeneous distribution of the grains. This can lead to an improvement in the mechanical properties of the materials [14]. The Al-doped Li-Co ferrites are a promising class of magnetic materials that have a wide range of potential applications due to their excellent magnetic and microwave properties. The Al-doped Li-Co ferrites concentration was synthesized by the auto- combustion method. The detailed structural studies were done through XRD, SEM, EDAX, and FTIR studies. Dielectrical, AC conductivity, and magnetic properties of these ferrites are also studied and controlled to optimize the properties of these materials for specific applications. 2. Experimental 2.1. Samples preparation The sol-gel auto combustion method is a commonly used technique for synthesizing oxide materials, including spinel ferrites such as Li0.5Co0.75AlxFe2−xO4 (x = 0.15, 0.30, 0.45, and 0.60). Here are the steps to synthesize this material using the sol-gel auto combustion method: Characterization and Application of Nanomaterials 2025, 8(2), 11330. 3 2.2. Preparation of precursor sol The first step in the process is the preparation of a precursor sol, which is a stable colloidal suspension of nanoparticles in a liquid medium (water). In this case, the precursor compounds used are LiNO3, Co(NO3)2∙6H2O, Al(NO3)3∙9H2O, Fe(NO3)3∙9H2O, and C6H8O7∙H2O form SD Fine-Chem Ltd (India). These compounds are dissolved in a suitable solvent (water)used to prepare the sol. A stabilizing agent, such as citric acid, is also added to prevent the agglomeration of nanoparticles. LiNO3 + Co(NO3)2∙6H2O + Al(NO3)3∙9H2O + Fe(NO3)3∙9H2O + C6H8O7∙H2O → Li-Co-Al-Fe-Citrate + NO2 + H2O 2.3. Gelation The sol is then subjected to a gelation process, which transforms the liquid sol into a solid gel matrix. Gelation can be achieved by several methods, including evaporation, cooling, or chemical crosslinking. In this case, the gelation is achieved by heating the sol at a temperature of around 80°C for several hours until a solid gel is obtained. Li-Co-Al-Fe-Citrate → Li-Co-Al-Fe-Citrate Gel 2.4. Auto-combustion The solid gel matrix was initially heated at 120℃ to remove excess water, followed by auto-combustion at approximately 250°C, and final sintering at 800°C for 4 h. The solid gel matrix is then heated to a high temperature to trigger the auto- combustion process. This process involves an exothermic chemical reaction between the precursor compounds and the stabilizing agent, which generates heat and produces the desired oxide products. In the first step, C6H8O7∙H2O (citric acid) acts as a fuel and reacts with LiNO3 to produce Li5C6H3O7 (lithium citrate), NO2, and H2O. The lithium citrate then reacts with the metal nitrates to form the desired oxide products, along with CO2, H2O and NO2. The exact stoichiometry and properties of the final product depend on the composition and combustion conditions used in the process. 2.5. Final product formation Li-Co-Al-Fe-Citrate Gel → Li0.5Co0.75AlxFe2−xO4 + CO2 + H2O + NO2 The heat generated during the auto-combustion process at ambient air causes the solid products to crystallize and form Li0.5Co0.75AlxFe2−xO4(x= 0.15, 0.30, 0.45, and 0.60). 3. Results and discussion 3.1. Powder XRD analysis X-ray diffraction (XRD) of samples done by Rigaku Smartlab SE (fully automated computerized powder XRD); X-ray tube: CuAngular range (2θ): 2° to 80° with Cu-Kα radiation (λ = 1.5406 Å). The powder specimen of the crystal can be thought of as a group of microscopic crystals that are randomly oriented and present a range of glancing angles to the incident beam. There can only be one value of the Characterization and Application of Nanomaterials 2025, 8(2), 11330. 4 glancing angle that fulfils the equation 2dsin = n, where n = 1, for a given wavelength and a given value of d. Such reflected beams, which are slanted at an angle of 2 with the direction of the incident beam, radiate out from the specimen in all directions. 𝑑 = 𝑎 √ℎ2+ 𝑘2+𝑙2 Å. where, a = lattice constant, (hkl) = Miller indices. The lattice constant is calculated by the relation [14,15], 𝑎 = 𝜆 2sin𝜃 √ℎ2 + 𝑘2 + 𝑙2 where, λ = wavelength of monochromatic X-rays, = glancing angle. Knowing the values of and (hkl), the lattice constant may be computed for the prominent line in the spinel diffraction pattern, which corresponds to the (311) plane. We may determine the interplanar spacing by obtaining the values of the Miller indices and lattice constant. 𝑑 = 𝜆 2sin𝜃 or𝑑 = 𝑎 √ℎ2+𝑘2+𝑙2 where, λ = wavelength of Cu-kα (1.5406 Å),= glancing angle. The average particle size of each sample is calculated from the relation [16]. 𝐷 = 0.9𝜆 𝛽cos𝜃 . β= full width half maximum corresponding to the highest peak of the (311) plane. Similarly, dislocation density(ρ), lattice strain(ε), and porosity(P) are calculated from the following relations [17]. 𝜌 = 1 𝐷2 , 𝜀 = 𝛽cos𝜃 4 , 𝑃 = 𝑑𝑥−𝑑𝑎 𝑑𝑥 × 100, 𝑑𝑥 = 𝑋 − ray density = 𝑍𝑀 𝑁𝑎3. Hopping lengths (LA and LB), Tetrahedral location for A,𝐿𝐴 = √3 4 𝑎 Å. Octahedron location for B, 𝐿𝐵 = √2 4 𝑎 Å. where Z is the number of molecules per cell, N is Avogadro’s number (6.02×1023), ais the lattice constant, and da is the actual density, which is equal to the mass divided by the volume of the pellet in grams. The X-ray diffraction (XRD) patterns of the Li(0.5)Co(0.75)AlₓFe(2−x)O4 spinel ferrites are presented in Figure 1. All samples exhibit a face-centered cubic (FCC) spinel structure, with no detectable secondary phases, confirming the formation of a single-phase material. The absence of any impurity peaks further supports the phase purity of the synthesized ferrites. Among the diffraction peaks, the (311) plane is observed to have the highest intensity, which is characteristic of spinel ferrites and consistent with previously reported data. The indexed diffraction peaks correspond to the (111), (220), (311), (222), (400), (422), (511), and (440) planes, aligning well with standard spinel ferrite patterns and reinforcing the structural integrity of the material. Characterization and Application of Nanomaterials 2025, 8(2), 11330. 5 The lattice parameters, calculated using Bragg’s law, exhibit a close correlation with the experimentally observed interplanar spacings, as summarized in Table 1. This agreement validates the precision of the structural analysis and confirms the successful incorporation of Al3⁺ into the spinel lattice. Figure 1.XRD patterns of Li0.5Co0.75AlxFe2−xO4(x= 0.15, 0.30, 0.45, and 0.60). The variation of lattice parameter with composition is shown in Table 1. From the table it is observed that the lattice constant (a) decreases with an increase in composition. Which is attributed to the fact that as composition Al increases, the amount of Fe decreases. Because the ionic radius of Al3+ (0.53 Å) is less than that of Fe3+(0.77 Å), hence the lattice constant tends to decrease with composition, obeying Vegard’s law. The observed deviation in lattice parameter is due to the rearrangement of Al and Fe ions. The variation of crystallite size with composition is depicted in Table 1. From the table, it is observed that the crystallite size nearly varies from 9 nm to 28 nm. The size is found to decrease with an increase in the composition of Al. The porosity varies from 23% to 48% depending upon the method of preparation, purity of samples, and sintering temperature (Table 1). It is due to the fact that X-ray density is greater than that of actual density because of the presence of pores in the material, depending on the method of preparation and sintering condition. Table 1. Data on lattice constant, average particle size, dislocation density, lattice strain, and X-ray density. Composition, x Lattice constant, Å Avg. particle size, D in nm Dislocation density, ρ in ×1016m−2 Lattice strain, ε×10−3 X-ray density, dx (g/cc) Hopping length LAÅ LBÅ 0.15 8.3462 29 0.121 1.218 5.004 3.613 2.950 0.30 8.3408 20 0.283 1.845 4.912 3.611 2.948 0.45 8.3528 15 0.437 2.293 4.781 3.616 2.952 0.60 8.3663 9 1.274 3.913 4.752 3.600 2.939 Characterization and Application of Nanomaterials 2025, 8(2), 11330. 6 3.2. FTIR analysis Figure 2 presents FTIR spectra. The vibration mode of the space group Fd3mOℎ 7 exhibits four IR active fundamentals in the spinel ferrites with FCC structure. The largest restoring force is associated with the inherent vibrations of tetrahedral complexes, whereas bond-bending vibrations are associated with octahedral complexes. Hence, it is anticipated that 𝜈1 > 𝜈2. Table 2 displays two distinct lines in the ranges of 572 cm−1 to 539 cm−1 and 496 cm−1 to 455 cm−1, respectively. Fe3+–O2− distance changes in the octahedral and tetrahedral complexes may be the cause of the minor shift in frequency with composition. Due to the presence of Fe2+, which locally causes lattice deformation because of a non-cubic component of the crystal field potential, the Jahn-Teller effect splits the bands 𝜈1and 𝜈2. In contrast, Fe3+ ions don’t have these effects [18,19]. Figure 2. FTIR spectra of Li0.5Co0.75AlxFe2−xO4. Table 2. Data on FTIR absorption bands of Li0.5Co0.75AlxFe2−xO4 ferrites. Composition, x Absorption bands 𝝂𝟏 (cm−1) 𝝂𝟐 (cm−1) 0.15 539 455 0.30 555 457 0.45 539 455 0.60 535 455 3.3. Scanning electron microscope analysis The samples’ SEM (Jeol JSM/JSM-IT500LA, magnification up to 300,000×Resolution: 3nm Acc. Voltage up to 30kV Max. specimen size: 200mm Dia×75mm height (fully computer-controlled carbon, gold coating) micrographs are shown in Figure 3. The features shown in these micrographs are as follows. The sample’s porosity ranges from 23% to 48% since the sol-gel process was used to Characterization and Application of Nanomaterials 2025, 8(2), 11330. 7 prepare them. The size of the grain varies between 17 and 26 m depending on the heat treatment. If x=0.15, the largest grain size is discovered. At the base of the neck and the neck, porosity forms as a result of uneven diffusion rates. The characteristic microstructure of ferrites, in which residual porosity manifests in intra granular space, is the outcome of the mechanism of pore expansion in conjunction with grain growth. Table 3 shows that average grain diameter reduces as aluminium content rises. The presence of a particular number of metal ion vacancies brought on by the oxidation of a suitable dopant is what causes the diameter to expand [20,21]. Figure 3. SEM spectrum of the Li0.5Co0.75AlxFe2−xO4. Table 3. Data on actual density, porosity, and grain size. Composition ‘x’ Actual density g/cc Porosity ‘P’% Average grain diameter ‘D’ in µm 0.15 3.136 23.10 25.9 0.30 3.179 39.73 22.70 0.45 3.042 36.37 20.22 0.60 2.452 48.42 17.48 Characterization and Application of Nanomaterials 2025, 8(2), 11330. 8 Figure 4. EDS analysis of the Li0.5Co0.75AlxFe2−xO4. The elemental composition of the synthesized ferrites was confirmed using Energy Dispersive X-ray Spectroscopy (EDS). The EDX sample peaks are shown in Figure 4, revealing that the FCC structure is formed without any impurity. The identified elements from the EDX are Co, Al, Fe, and O, in which lithium (Li) is absent. Lithium is a light element with a low atomic number and is typically not detected using EDS due to its weak X-ray emission and other elements detected listed in Table 4. Table 4. The percentage of trace elements present in the ferrite. x 0.15 0.30 0.45 0.60 Elements Weight% Atomic% Weight% Atomic% Weight% Atomic% Weight% Atomic% C K 3.53 7.90 3.97 8.73 2.97 6.50 4.64 10.03 O K 33.01 55.42 32.62 53.77 33.67 55.37 33.14 53.77 Mg K 8.26 9.13 8.76 9.51 9.03 9.77 7.33 7.82 AL K 1.95 1.94 4.33 4.23 5.49 5.35 5.77 5.55 Fe L 53.24 25.61 50.32 23.76 48.84 23.01 49.13 22.83 3.4. Dielectric properties analysis The sample in pellet form is used to measure capacitance (Cp) and dielectric loss (ε) at room temperature in the frequency range from 20Hz to 1MHz by the two-probe method (HIOKI-IM3570 high-precision impedance analyzer interfaced to a computer in the frequency range from 4 Hz to1 MHz). The dielectric constant is calculated by the relation [22]. ∈= 𝐶𝑝𝑡 ∈0𝐴 . where, Cp—capacitance of the parallel plate capacitor in Farad, t—thickness of the pellet in meter,∈0—permittivity of free space in SI unit, A—area of cross section of Characterization and Application of Nanomaterials 2025, 8(2), 11330. 9 pellet in m2. The AC conductivity is related to dielectric relaxation, caused by localized electric charges. The frequency-dependent AC conductivity is calculated from the relation: 𝜎𝐴𝐶 = 2π𝑓 ∈0∈. where, f = frequency of applied electric field in Hz, ∈0—permittivity of free space in SI unit,∈—dielectric constant. All the samples exhibit dispersion (Figure 5a,b) in dielectric constant in the frequency range of 20 Hz to 1 MHz. Beyond this range, it does not remain constant; it may be constant above 5 MHz. The dispersion in dielectric constant obeys Maxwell- Wagner type interfacial polarization, in agreement with Koop’s phenomenological theory. The large values of the parameter at low frequency are due to space charge polarization at grain boundaries, interfacial dislocation, oxygen vacancies, grain defects and predominance of large Fe3+ ions [23] and abstraction belonging to the polarization due to changes in valence states of cations and space charge polarization. At higher frequencies the dielectric constant remains independent of frequency (f) due to the lack of ability of electric dipoles to follow the fast variation of the alternating applied electric field [24].When grain size decreases, grain boundary area and porosity decrease, but in this case, porosity increases due to many effects like method of preparation, sintering condition, etc. This substitution of lithium affects grain growth, typically leading to a reduction in particle size, which in turn influences dielectric behavior. Smaller particles increase grain boundary resistance, thereby enhancing dielectric constant and loss at lower frequencies. The decrease in the parameter with frequency is due to lagging of polarizability behind the applied field at higher and higher frequency. Due to impurities and flaws in the crystal lattice, polarization sometimes lags behind the applied AC field, which results in dielectric loss [17,22– 24]. The period of rest, which is comparable to the applied field duration, is what causes the most loss. The dielectric becomes tiny if the relaxation time is longer than the applied field period, and vice versa. The AC conductivity of Li-Co ferrites generally increases with increasing frequency, exhibiting semiconducting behavior due to hopping mechanisms of charge carriers, especially electrons between Fe2+ and Fe3+ ions shown in Figure 5c. The conduction mechanism in ferrites is due to electrons and polarons following the hopping model suggested by Austin and Moot. The inverse tangential increase in conductivity with frequency is attributed to small polarons. Such behavior is found in all the ferrite samples. The variation in hopping length is the distance between ions in A and B sites, which governs the conduction mechanism as shown in Table 5. The same reports have been reported in the case of Li-Ni-Cu nano ferrites [17]. Characterization and Application of Nanomaterials 2025, 8(2), 11330. 10 Figure 5. Dielectric studies of Li0.5Co0.75AlxFe2−xO4 nano ferrites (a) dielectric constant; (b) dielectric loss factor; (c) AC conductivity. Table 5. Data on porosity, hopping length, and AC conductivity at 1 MHz. Composition, x Lattice constant, a Å Porosity, P % AC conductivity, σ Sm−1 0.15 8.3482 23.10 28,513.712 0.30 8.3408 39.73 50,295.760 0.45 8.3528 36.37 21,300.360 0.60 8.3163 48.42 12,199.196 3.5. Magnetic properties analysis The specification of the VSM analyzer: Lakeshore, model: 7410 series. The variation of saturation magnetization vs. alternating magnetizing field of all the samples at room temperature (300 K) is shown in Figure 6. The data on saturation magnetization, magnetic moment, and Hc are given in Table 6. Characterization and Application of Nanomaterials 2025, 8(2), 11330. 11 Figure 6. Magnetic properties study of Li0.5Co0.75AlxFe2−xO4 nano ferrites. Table 6. Different magnetic parameters for all Al-substituted Li-Co ferrites. Composition, x Molecular weight, M Saturation magnetization, Ms 𝝁𝑩 Coercivity (Hc) (Oe) Porosity 0.15 219.02 3.97 0.1556 512 37.36 0.30 214.69 1.33 0.0511 498 46.06 0.45 210.36 1.43 0.0538 473 36.37 0.60 206.03 1.36 0.0501 447 52.71 The variation of magnetic moment with Al can be explained as follows. Both Al and Li are nonmagnetic in nature. As the amount of Al increases, the amount of Fe3+ ions on both A and B sites decreases. As a result, magnetization goes on decreasing with an increase in Al. However, the variation of Ms with composition is attributed to the density of the sample. This then results in the weakening of A–B exchange interactions and decreases the saturation magnetization. At x = 0.15, it exhibits the highest saturation magnetization (~4 emu) due to the strong Fe3⁺–O2⁻–Fe3⁺ super exchange interactions. As Al3⁺ substitution increases (x = 0.30 to 0.60), the magnetization decreases because non-magnetic Al3⁺ ions replace Fe3⁺, weakening the overall magnetic interactions. This substitution disrupts the spin alignment, leading to a decline in the net magnetic moment. This then results in the weakening of A–B exchange interactions and increases the saturation magnetization [25–27]. Due to polarization effects, they prefer tetrahedral and octahedral sites, and the presence of non-magnetic lithium-aluminium ions in these sites results in lower values than both sites and consequently enhancement of Ms values [27–29]. Similarly, the coercivity is highest for x = 0.15, indicating hard magnetic behavior. As Al3⁺ content increases, it decreases, suggesting a transition to a softer magnetic nature. This reduction in coercivity results from the dilution of magnetic interactions and a decrease in anisotropy, making the material easier to magnetize and demagnetize. The observed changes confirm that Al3⁺ substitution significantly influences the structural and magnetic properties of Li(0.5)Co(0.75)AlₓFe(2−x)O4 spinel ferrites. Microstructure is a significant additional aspect that affects ferrites’ ability to magnetize. Every grain possesses a unique magnetic moment. The magnetic circuits between the grains are Characterization and Application of Nanomaterials 2025, 8(2), 11330. 12 broken by the pores. As a result, there are net reductions in magnetic moment and an increase in porosity. Smaller numbers of big grains are formed at higher a sintering temperature, which reduces porosity. Hence, magnetism rises as sintering temperature rises [26–29]. 4. Conclusion In conclusion, the study investigated the effects of aluminium doping on the structural, electrical, and magnetic properties of Li(0.5)Co(0.75)AlxFe(2−x)O4 spinel ferrites (x =0.15 to 0.60) synthesized using the sol-gel auto-combustion technique. The results showed that the samples had a single-phase cubic spinel structure with Fd-3m space group, confirmed by XRD analysis. SEM images showed the creation of homogeneous particles with an average size of about 21 nm. FTIR spectra confirmed the presence of spinel ferrite phases in all samples. The DC electrical conductivity increased with increasing aluminium content up to x = 0.45 before dropping at x = 0.60. The maximum saturation magnetization value was found at x = 0.45, indicating a strong correlation between the magnetic properties and the amount of aluminium. Therefore, the study suggests that the addition of aluminium can significantly enhance the magnetic and electrical properties of Li(0.5)Co(0.75)Fe(2)O4 spinel ferrites, up to a certain point, which can be beneficial for various technological applications. Author contributions: Conceptualization, KPM and MGK; methodology, SVA; software, KPM and MGK; validation, LDH, SNM, SSK, CSH, MSB and RBP; formal analysis, RBP, SSK and SNM; investigation, KPM and MGK; resources, KPM, MGK and RBP; data curation, KPM and MGK; writing—original draft preparation, KPM, MGK and SSK; writing—review and editing, SNM and RBP; supervision, SNM and RBP; project administration, CSH, LDH and RBP. All authors have read and agreed to the published version of the manuscript. Institutional review board statement: Not applicable. Informed consent statement: Not applicable. Conflict of interest: The authors declare no conflict of interest. References 1. Kakati S, Rendale MK, Mathad SN. 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