Effect of Selective Substitution on the Microstructure and Properties of Bi2Sr2Ca2Cu3O10 Superconductor

Pham V. Huong ； Hui Wang ； A. L. Verma ； Seong-Han Kim ； Dong-Hoon Lee ； Keu-Hong Kim

《Chinese Journal of Physics》 31卷6S期 (1993/12) Pp. 1151-1156

並列摘要

Selective doping on Bi, Sr and Cu sites in Bi-Sr-Ca-Cu-0 superconductors were made and the resulting materials were characterized by I. C. P., resistivity measurements, X-ray diffraction, Infrared and Raman micro-spectroscopy, etc.In barium doped materials Bi2Sr2-xBaxCa2Cu3Oy with initial x0 varying from 0 to 0.5, only very few bismuth sites are found to be affected by substitution; the pyramids remain in staggered positions along the c axis. The substitution of Ba in Sr sites leads to a lowering of the Bi-0 stretching frequencies along the c axis, both in Raman and Infrared spectra as the Ba dopant amount increases. This is in agreement with a redistribution and lengthening of the Bi-0 distances along the c axis. X-ray diffraction supports this conclusion in showing an expansion of the lattice parameter c from 37.12 Åin Barium free material to 37.19 Åin heavily Barium doped (x = 0.25) materials. The re-appearance of the Raman doublet at 650-630 cm-' with Ba doping indicates an increase in structural modulation compared to Ba free (Bi/Pb)2223.These results are analyzed in comparison with those obtained on selective substitution on bismuth sites with Pb, and on copper sites with lithium.