Optimization of the Pr doping in the

1. Optimization of the Pr doping in the (Bi1.7Pb0.3)(Sr2-xPrx)CuO6+superconducting series Y. C. Chu1(朱禹臻), H.-C. I. Kao1(高惠春), D. C. Ling2(林大欽), H. S. Sheu3 (許火順)and T. S. Chan3(詹丁山) 1Department of Chemistry, Tamkang University, Tamsui 251, Taiwan 2Department of Physics, Tamkang University, Tamsui 251, Taiwan 3National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan *virus777787@hotmail.com Abstract A series of Bi-2201 having the nominal composition of (Bi1.7Pb0.3)(Sr2-xPrx)CuO6+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 • Bulk samples of (Bi1.7Pb0.3)(Sr2-xPrx)CuO6+ were prepared by a conventional solid-state reaction method. • 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. • Unit cell parameters were determined by the Rietveld refinement method. GSAS for the structure analysis. Tc measured by a standard 4-probe method. Oxygen stoichiometry and the hole concentration of the compound were determined by an iodometric titration method. • All of them are single-phase compounds with orthorhombic crystal system. • Impurity phases SrCuO2+ and related compounds, were not found. • The Rwp obtained from the Rietveld refinement on this samples is between 810%. • The space group of Amaa is used for the Rietveld analysis for the single phase samples. • The a- and c-axis decrease with increasing x, while the b-axis increases with increasing x. • Pr successfully replaces the position of Sr site. Fig. 2. Rietveld refinement result of a (Bi1.7Pb0.3)(Sr2-xPrx)CuO6+ with x = 0.40. Fig. 3. Unit-cell axes dependence with x for the (Bi1.7Pb0.3)(Sr2-xPrx)CuOy samples. Fig. 1. XRD patterns of (Bi1.7Pb0.3)(Sr2-xPrx)CuOy samples with (0.050  x  0.50). 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) L2080. [4] H. Maeda, Y. Tanaka, M. Fukutomi, and T. Asano, Jpn. J. Appl. Phys. 27 (1988) L209. [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. 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. • Oxygen stoichiometry increases and hole concentration decreases with increasing Pr content. • 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 (Bi1.9Pb0.1)(Sr2-xPrx)CuOy samples. Fig. 5. Tc dependence with hole concentration (p) for (Bi1.9Pb0.1)(Sr2-xPrx)CuOy samples. Acknowledgment This work is financially supported by the National Science Council of Taiwan.