X-RAY STRUCTURE STUDY OF THE HIGH-T-C PHASE OF THE BI(PB)-SR-CA-CU-O SYSTEM

Bulk samples of tile (Bi,Pb)-Sr-Ca-Cu-O system were prepared by solid state reaction. The superconducting characteristics of samples with do minant 2223 phase were examined as a function of nominal lead concentr ation as well as their preparation. It is shown that for samples quenc hed in liquid nitrogen the superconducting transition temperatures T-c registered are lower than those for slowly cooled samples. This effec t cannot be ascribed to concentration variations. X-ray diffraction (X RD) data are analysed using the Rietveld technique. The structure refi nements enable to investigate small structure changes that can be rela ted to variations of the lead substitution in Bi-O planes.