Synthesis of the Bi-2222 Compounds of Bi–Sr–Ln(Zr)–Cu–O (Ln = Sm,Eu, Gd,and Dy) |
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Authors: | Hiroyuki Sasakura Yoshiya Akagi Shigeki Tsukui Takashi Oka Motoaki Adachi |
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Affiliation: | (1) Department of Physics, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, Shizuoka 431-3192, Japan;(2) Department of Chemical Engineering, Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan;(3) Department of Quantum-Beam Science, Frontier Science Innovation Center, Osaka Prefecture University, Sakai, Osaka 599-8570, Japan |
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Abstract: | Bi-based superconducting compounds with the 2222 structure has been already synthesized in the Bi2Sr2- (Ln1−x Ce x )2Cu2O10+y (Ln = Sm, Eu, and Gd) systems. One of the characteristics of these compounds is the existence of the fluorite-like (Ln1−x Ce x )2O2 block between two CuO5 pyramids in the crystal structure. The tetravalent ions of Ce4+ are reported to be necessary to stabilize the 2222 structure. Recently, we have discovered that the Bi-2222 phase could be composed in the Bi2Sr2(Ln2−x Zr x )Cu2O z (Ln = Sm, Eu, Gd, and Dy) systems, where Zr4+ is used as a new tetravalent ion stabilizing the 2222 structure in stead of Ce4+. In the new system, nearly single 2222 phase samples have been obtained at the nominal composition of x=0.5 (Ln = Sm, Eu, and Gd) and in the range of 0.1≤x≤0.3 (Ln = Dy). Among them, the sample with Ln = Gd has the smallest resistivity at 273 K. But it is a semiconductor, and the conduction process at low temperatures is assumed to be followed by a two-dimensional VRH. The experimental results for the Gd samples with a partial substitution of Pb for Bi in the Bi2Sr2(Gd2−x Zr x )Cu2O z system are also reported. |
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Keywords: | Bi– Sr– Ln(Zr)– Cu– O system Bi-2222 phase Resistivity Magnetic susceptibility Pb substitution for Bi |
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