SUPERCONDUCTING PROPERTIES AND STRUCTURAL STUDY OF BI2-XPBXSR2CA1-XYXCU2O8(0-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1)

A solid solution has been prepared by coupled substitution of lead for bismuth and yttrium for calcium in the Bi2Sr2CaCu2O8 cuprates. Pure phases Bi2-xPbxSr2Ca1-xYxCu2O8 were obtained from x = 0 to x = 1. The superconducting properties of the samples vary with x: Tc remains close to 85 K up to x = 0.5 and then decreases drastically. The variation of the cell parameters has been studied: the oxides possess an orthorhombic cell with a = 5.385 angstrom, b = 5.424 angstrom, and c = 30.316 angstrom, with a space group Pnam for x = 1. The electron diffraction patterns are complex; several types of satellites have been observed and were correlated with distortions, twins, and short-range order phenomena. Local variations of the Bi/Pb ratio most likely occur and could be responsible for the change in Tc.