مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 عة السینیة و درجة الحرارة االنتقالیة للمركب شقیاسات اال Bi2Sr2La2Cu3O10+δ المطعم بالكالسیوم الفائق التوصیل محمد عبد النبي ثجیل ابن الھیثم، جامعة بغداد -قسم الفیزیاء ،كلیة التربیة 2011 ایار10: قبل البحث في، 2011 اذار30:استلم البحث في ألخالصھ CaO في خصائص مركب البزموث الفائقة التوصیل بإضافة كمیات مختلفة من التطعیم بالكالسیوم درسنا تأثیر +Bi2Sr2La2-xCaxCu3O10إلى المركب δ.وقد حصلنا على ثالث نماذج هي A (x=0.4) و ، B (x=0.4) و C (x= 0.8) یل . لتقلیدیة في ظل الظروف المثلیاتوقد حضرت النماذج بطریقة تفاعل الحالة الصلبة ا وأظهر تحل ذو تركیب معیني قائم مع ) C(ذو تراكیب رباعیة الشكل بینما االنموذج ) B وA(عینات األشعة السینیة أن النماذج تم قیست ألمقاومیة. للعینات المطعمة بالكالسیوم بالمقارنة مع العینة الخالیة منهcانخفاض في قیمه ثابت الشبیكه ذو ) A(الكهربائیة عند درجات حرارة مختلفة تحت المجاالت المغناطیسیة الصفریة و أظهرت تفسیر البیانات أن العینة ة بأنها أظهرت ) C(عینة بینما ال " معدنیا" أظهرت سلوكا) B(سلوك شبه موصل، و العینة موصل فائق التوصیل ذو درج .K 85 حرارة التحول عند المقاومة صفر تساوي لمفتاحیه لكلمات أ تحلیالت األشعة السینیة، درجة حرارة التحول ،ألمقاومیه الكهربائیة -:ا مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 X-ray Data and Transition Temperature Measurements of Ca Doped Bi2Sr2La2Cu3O10+δ Superconductor M. A. Thejeel Department of Physics, College of Education Ibn-Al-Haithem, University of Baghdad Received in : 30 March 2011 ,Accepted in : 10 May 2011 Abstract We studied the effect of Ca- doping on the properties of Bi-based superconductors by adding different amounts of CaO to the Bi2Sr2La2-xCaxCu3O10+δ compound. consequently, we obtained three samples A,B and C with x=0.0, 0.4 and 0.8 respectively. The usual solid-state reaction method has been applied under optimum conditions. The x-ray diffraction analysis showed that the samples A and B have tetragonal structures conversely the sample C has an orthorhombic structure. In addition XRD analysis show that decreasing the c-axis lattice constant and thus decreasing the ratio c/a for samples A,B and C respectively. The X-ray florescence proved that the compositions of samples A,B and C with the ratio of Bi:Sr:La(Ca):Cu which were about 2:2:2:3. Resistivity were measured at different temperatures under zero magnetic fields and the data were interpreted. Sample A shows that semiconductor behavior, sample B showed a metal behavior and sample C showed a superconductor behaviors with transition temperature at zero resistance Tc(offset) were 85 K . Key words: Resistivity, t ransition temperat ure and x-ray diffract ion analysis Introduction Superconductors Bi-base are very sensitive to synthesis conditions. They change from semiconductors to metal, from metal to superconductors, or from superconductors at low Tc to high Tc superconductors without losing their crystalline structuere(1). The high sensitivity of superconductors to partial replacement by elements have cations higher oxidation states and oxygen content. oxygen content is due to the apparent ease to which oxygen can move in and out of the atomic lattice(2,3). Bi2Sr2Ca2Cu3O10+δ (2223) system is still difficult to synthesize in its pure form, the reason is that the formation of the (2223) phase is a very slow process taking place within a very limited temperature range, moreover, the weak bonding along the c-axis may also contribute to its stronger propensity to form intergrowth products(4) . To obtain a high quality 2223 monophase superconductor, the basic and significant knowledge needed is about the thermodynamic process of the Bi-system (5), the forming mechanisms and the inter relation of the two superconducting phases 2212 and 2223. The nucleation of (2223) can be formed, if additional layer of perovskite –like Cu-Ca-O is inserted into the (2212) matrix. This inserting process can occur under the sintering temperature through the fluctuation of component and energy (6). In the present work, we have successfully to prepare Bi2Sr2La2-xCaxCu3O10+δ bulk polycrystalline superconductor by using solid state reaction process, we analyze the structure مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 and study the electrical properties of Ca-doped Bi2Sr2La2Cu3O10+δ superconductor synthesized at the optimum conditions. Experimental The Bi2Sr2La2-xCaxCu3O10+δ samples with different Ca (x=0.0, 0.4, 0.8) were prepared by the standard solid state reaction method using mixed powder of BiO, Sr La2O3, CaO and CuO with a purity of 99.99%. The starting materials were carefully mixed and ground in a mortar. The powders were calcined in air at 800°C for 3 hours with several intermittent grindings, and furnace cooled. The composition of prepared samples was checked by the powder XRF analysis in order to find the actual Bi/Sr/Ca/La/Cu ratio .The powder was pressed into disc- shaped pellets (1.3 cm) in diameter and (0.2-0.3) cm thick, using hydraulic press under a pressure of 7 ton/cm 2 .The pellets were presintered in air at (855-860) 0C for (12) hours with a rate of 250 0C/hr and then cooled to room temperature by same rate of heating.The presintered pellets were reground, repressed and resintered in the oxygen (oxygen rate 0.2 L/min) at the same range of temperature for further (6) hours and then cooled to (500) C and annealed in oxygent for (4) hours and then cooled to room temperature by same rate of heating. The exess of oxygen content (δ) as well as measuring the critical temperatures by the four - point technique have been described elsewhere (7). The X-ray diffractometer was used to confirm the resultant phase of the samples. Results and Discussion The variation of resistivity with temperature of as synthesized Bi2Sr2La2-xCaxCu3O10+ δ samples was measured by the standard four-probe technique. The normal state resistivity of all the samples showed semiconductors or metal behaviors with respect to temperature. The temperature dependence of the resistivity (ρ) samples with different Ca in Bi2Sr2La2- xCaxCu3O10+δ for (x=0.0,0.4,0.8) is shown in figure (1). It is found from this figure that the behavior of resistivity (ρ) with the temperature for the sample A with x=0.0 is semiconductor behavior, sample B showed a metal behavior at x = 0.4, sample C showed a superconductor with transition temperature at zero resistance Tc(offset) were 85 K at x = 0.8. The compositions of the samples were determined by XRF analysis. The x-ray Florescence patterns of Bi2Sr2La2-xCaxCu3O10+δ superconductors are shown in figures (2,3 and 4). The ratio of Bi:Sr:La(Ca):Cu were found to be about 2:2:2:3. According to the X-ray diffraction data for the samples consisted of almost phase-pure polycrystalline Bi-2223 phase. Fig. (5) shows XRD patterns taken in x=0.0, 0.4, and 0.8, respectively. It shows that all our samples are consisted of a major 2223 phase and very small amounts of secondary phases such as SrBiO , Sr,La. Cu-Oδ Sr,Ca and CuO. The comparison between the relative intensities of XRD patterns for the samples with Ca = 0, 0.4 and 0.8, with the relative intensity of the same reflections of the sample with La =0.0 shows that High- Tc phase reflections of the free sample (Ca= 0) has lower intensity than samples have Ca . The lattice parameters have been estimated using d-values and (hkl) reflections of the observed x- ray diffraction pattern through the software program based on Cohen,s least square method(8) , the parameters a, b, c and C/a are shown in table(1). Figure (6) shows decreasing c/a as comparable with the free sample, due to the substitution of Ca which has the ionic radius Ca+2 (2.23A 0 ) smaller than that of La +3 (2.74A 0 ) which render c-parameter to be smaller or get deformed. مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Conclusions In the present study, we have investigated the effect of simultaneous doping of Ca in La- Oδ layer of Bi2Sr2La2-xCaxCu3O10+ δ. The substitution of Ca for La ions yields further holes thus they will modulate the structure by influencing the charge balance, oxygen distribution and relevant interactions process between the neighboring layers will lead to create more holes in the Cu-O layers. The transition temperature of as grown samples is found to be sensitive to the Ca concentrations it has been observed that maximum Tc (85 K) is achieved for Bi2Sr2La1.2Ca0.8Cu3O10.24 . X-ray diffraction(XRD) analysis showed tetragonal structure (samples A and B) and an orthorhombic structure (sample C) with decrease of the c-axis lattice constant for the samples doped with calcium as compared with this has no calcium content . It was found that the change of the Ca concentrations of all our samples produce a change in the C/a and lattice parameters. References 1- Jasim, K.A. (2005 )Comparison Study of Tc Between the Superconducting Compounds Bi2-x(Hg,Pb)xSr2-y BayCa2Cu3O10+δ and Hg1-xPbxSr2-y BayCa2Cu3O8+δ , Ph.D Thesis , University of Baghdad , College of Science , Physics Dep. Iraq . 2- Pertanika, J. (2004) .Thennal Diffusivity Measurement of BSCCO Superconducto 135 - 129): 1(12!. Techno& . Using PVDF TransducerSci) K300 to 85 ( 3- Yutaka, I.; Masasuke, T.; Tsutomu, Y.; Mamoru, I. and Koinuma, H. (1989) (Formation of the High-Tc Phase of Bi1-xPbxSr0.90Ca1.10Cu1.50Oy (0≦x≦0.05), Jpn. J. Appl. Phys. 28: L1518-L1520 4- Mizuno M., Endo H., Tsuchiya J., Kijima N., sumiyama A., Tomii Y. and Mazaki H.,( Crystal Structure of the High-Tc Phase in the Pb-Bi-Sr-Ca-Cu-O System) (1989) Jpn. J.Appl. Phys., .28, pp. L787-L790 ,. 5- Kouji Yamawaki, Sasaki S.,.Tanaka M, Yamauchi H. and Lee S., (Single-crystal X-ray study of (Hg,Pb)-1223 superconductor at low temperature), (2000) Physica C,.338,.67- 71. 6- Chmaissem, Q.; Huang, O.; Capponi, J.J.; Chaillout, C.; Marezio, M.; Tholence, J.L. and Santoro, A.,( Neutron powder diffraction study of the crystal structure of HgBa2Ca4Cu5O12+δ at room temperature and at 10 K) (1994) , Physica C, 227 , 1-9 .. 7- Jasim K.A. (2009) Synthesis, X-ray data and electrical properties measurements of Bi doped TlSr2Ca2Cu3O9-δ superconductors , Journal of college of education ,university of Mustansiriya 84(1): 806-812 8- Ferguson I.F and.Rogerson A.H : A program for the calculation of the intensities of X-ray or neutron powder reflections, (1984), Comput. Phys. Commun., 32, 95 Table(1): Values of lattice parameter a,b, C/a, oxygen content (δ) and Tc for samples with different composition of Bi2Sr2La2-xCaxCu3O10+ δ X Tc (OFF)(K) δ(o2) a(A0) b(A0) c(A0) C/a 0.0 ------ -------- 5.402 5.421 37.78 6.99 مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Fig. (1): The resistivity dependence on Temperature for Bi2Sr2La2-xCaxCu3O10+ δ at indicated values of (Ca) at x =0.00, 0.4 and 0.8 0.4 ------ -------- 5.414 5.414 37.63 6.95 0.8 85 0.24 5.423 5. 423 37.32 6.80 مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Fig.(2) :XRF Patte rns for the sample Bi2Sr2La2-xCaxCu3O10+ δ for x=0.0 مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Fig.(3): XRF Patterns for the sample Bi2Sr2La2-xCaxCu3O10+ δ for x=0. 4 مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Fig.(4): XRF Patterns for the sample Bi2Sr2La2-xCaxCu3O10+ δ for x= 0.8 مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Fig.(5): XRD Patterns for the sample Bi2Sr2La2-xCaxCu3O10+ δ for A (x=0.0), B(x=0.4) and C (x=0.8) مجلة إبن الھیثم للعلوم الصرفة و التطبیقیة 2012 السنة 25 المجلد 1 العدد Ibn Al-Haitham Journal for Pure and Applied Science No. 1 Vol. 25 Year 2012 Fig.(6): C/a as function of different Ca for Bi2Sr2La2-xCaxCu3O10+ δ