Microstructure and superconducting properties of Bi2-xPbxSr2CaCu2Oy spherical particles transformed from an amorphous state prepared by a containerless melt solidification method

被引:0
作者
Fujii, H [1 ]
Kumakura, H [1 ]
Togano, K [1 ]
机构
[1] Natl Res Inst Met, Tsukuba, Ibaraki 3050047, Japan
来源
MATERIALS RESEARCH IN LOW GRAVITY II | 1999年 / 3792卷
关键词
containerless melt solidification; amorphous state; transformation; Pb-substituted Bi-2212; microstructure; transmission microscopy;
D O I
10.1117/12.351283
中图分类号
O7 [晶体学];
学科分类号
0702 ; 070205 ; 0703 ; 080501 ;
摘要
We successfully prepared amorphous Bi-Pb-Sr-Ca-Cu-O (Bi:Pb:Sr:Ca:Cu:O=2-x:x:2:1:2:y) spherical particles by a containerless melt solidification method. These particles were obtained by the melt solidification of Bi2-xPbxSr2CaCu2Oy ((Bi,Pb)-2212) powder during the free-fall using a propane gas torch. The diameter of these particles was about 100 mu m. The crystalline (Bi,Pb)-2212 superconductors were obtained by the transformation from the amorphous state under several oxygen partial pressures (P-O2=0.01, 0.21 and 1 atm). (Bi,Pb)-2212 phase was formed via (Bi,Pb)(2)Sr2CuOy phase for all P-O2 values. Low P-O2 was more effective to introduce Pb into Bi2Sr2CaCu2Oy, lattice and only the heat treatment under P-O2=0.01 atm was successful in obtaining Pb-rich (Bi,Pb)-2212 with modulation-free structure. The critical composition separating Pb-poor modulated and Pb-rich modulation-free structures in (Bi,Pb)-2212 was x approximate to 0.5. However, no lamellar structure composed of modulated and modulation-free regions was present in any particles for all P-O2 values. Enhancement of critical current density was obtained by the Pb substitution.
引用
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页码:234 / 241
页数:8
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