Optimization of the Pr doping in the Bi

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Optimization of the Pr doping in the (Bi 1. 7 Pb 0. 3)(Sr 2 -x. Prx)Cu. O 6+ superconducting series Y. C. Chu 1 (朱禹臻), H. -C. I. Kao 1 (高惠春), D. C. Ling 2 (林大欽), H. S. Sheu 3 (許火順) and T. S. Chan 3 (詹丁山) 1 Department of Chemistry, Tamkang University, Tamsui 251, Taiwan 2 Department of Physics, Tamkang University, Tamsui 251, Taiwan 3 National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan *virus 777787@hotmail. com Abstract A series of Bi-2201 having the nominal composition of (Bi 1. 7 Pb 0. 3)(Sr 2 -x. Prx)Cu. O 6+δ with 0. 050 x 0. 50 was prepared by the solid state reaction method. All of them have the orthorhombic phase with a space group of Amaa. Orthorhombicity, 2 (a b)/(a + b), decreases with increasing the amount of Pr content. The highest Tc (20. 1 K) is found in the sample with x = 0. 40, which has an optimal hole concentration of 0. 278(2) analyzed by an iodometric titration method. Hole concentrations with respect to the amount of Pr substitution. Experimental u Bulk samples of (Bi 1. 7 Pb 0. 3)(Sr 2 -x. Prx)Cu. O 6+ were prepared by a conventional solid-state reaction method. u Mixed powder was calcined at 805°C for 26 h in a box furnace with five intermittent grindings. It was reground and pressed into pellets, sintered at 805°C for 24 h and quenched to room temperature. u Unit cell parameters were determined by the Rietveld refinement method. GSAS for the structure analysis. T c measured by a standard 4 probe method. Oxygen stoichiometry and the hole concentration of the compound were determined by an iodometric titration method. u All of them are single-phase compounds with orthorhombic crystal system. u The Rwp obtained from the Rietveld refinement on this samples is between 8 10%. u The a- and c-axis decrease with increasing x, while the b-axis increases with increasing x. u Impurity phases Sr. Cu. O 2+ and related compounds, were not found. u The space group of Amaa is used for the Rietveld analysis for the single phase samples. u Pr successfully replaces the position of Sr site. Fig. 1. XRD patterns of (Bi 1. 7 Pb 0. 3)(Sr 2 x. Prx)Cu. Oy samples with (0. 050 x 0. 50). Fig. 2. Rietveld refinement result of a (Bi 1. 7 Pb 0. 3)(Sr 2 -x. Prx)Cu. O 6+ with x = 0. 40. u. Oxygen stoichiometry increases and hole concentration decreases with increasing Pr content. u. It is a hole filling effect and the optimal Tc of 20 K with p = 0. 278(2) in the x = 0. 40. Fig. 4. Oxygen stoichiometry (y) and hole concentration (p) dependence with x for (Bi 1. 9 Pb 0. 1)(Sr 2 -x. Prx)Cu. Oy samples. Fig. 5. Tc dependence with hole concentration (p) for (Bi 1. 9 Pb 0. 1)(Sr 2 x. Prx)Cu. Oy samples. Acknowledgment This work is financially supported by the National Science Council of Taiwan. Fig. 3. Unit-cell axes dependence with x for the (Bi 1. 7 Pb 0. 3)(Sr 2 -x. Prx)Cu. Oy samples. Reference [1] J. B. Goodenough, J. Zhou, Phys. Rev. B 42 (1990) 4287. [2] C. Michel, M. Hervieu, M. M. Borel, A. Grandin, F. Deslandes, J. Provost, B. Raveau, Z. Phys. B 68 (1987) 421. [3] J. Akimitsu, A. Y. Amazaki, H. Sawa, H. Fujiki, Jpn. J. Appl. Phys. 26 (1987) L 2080. [4] H. Maeda, Y. Tanaka, M. Fukutomi, and T. Asano, Jpn. J. Appl. Phys. 27 (1988) L 209. [5] R. Yoshizaki, H. Ikeda, L. X. Chen, M. Akamatsu, Physica C 224 (1994) 121. [6] W. L. Yang, H. H. Wen, Y. M. Ni, J. W. Xiong, H. Chen, C. Dong, F. Wu, Y. L. Qin, Z. X. Zhao, Physica C 308 (1998) 294. [7] S. Ono, Y. Ando, Phys. Rev. B 67 (2003) 104512. [8] Z. Mao, C. Fan, L. Shi, Z. Yao, L. Yang, Y. Wang, Phys. Rev. B 47 (1993) 14467. [9] H. W. Zandbergen, W. A. Groen, F. C. Mijhoff, G. Tendeloo, S. Amelinckx, Physica C 158 (1988) 325. [10] P. L. Gay, P. Day, Physica C 152 (1988) 335. [11] A. K. Cheetham, A. M. Chippendale, S. J. Hibble, Nature 333 (1988) 21. [12] G. Xu, Z. Mao, X. Xu, M. Tian, L. Shi, Y. Zhang, J. Phys. Condens. Matter 9 (1997). 5137. [13] Z. Mao, M. Fain, M. Ji, J. Zhu, J. Zuo, R. Wang, Y. Zhang, Phys. Rev. B 49 (1994) 9857. [14] I. Chong, T. Terashima, Y. Bando, M. Takano, Y. Matsuda, T. Nagaoka, K. Kumagai, Physica C 290 (1997) 57. [15] T. Amano, M. Tange, M. Yokoshima, T. Kizuka, S. Nishizaki, R. Yoshizaki, Physica C 412 (2004) 230. [16] K. Osamuraa, S. Satoa, W. Zhanga T. Kizua, Physica C 186 (1991) 589. [17] A. C. Larson, R. B. von Dreele, Report La-UR-86 -748, Los Alamos National Lab. Los Alsmos, NM, USA (1990). [18] E. H. Appelman, L. R. Moress, A. M. Kini, U. Geiser, A. Umezawa, G. W. Crabtree, K. D. Carlson, Inorg. Chem. 26 (1987) 1834.

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