STUDY ON ANNEALING TREATMENT AND SR/CA RATIO FOR PB-SR-Y-CA-CU-O CERAMICS WITH 1212 STRUCTURE

The annealing effects of "1212" lead cuprate in a Pb-Sr-Y-Ca-Cu-O system were investigated. Samples with a nominal composition of (Pb0.7Cu0.3)Sr2(Y(1-x)Ca(x))Cu2O(y)(x = 0.4-0.7) were annealed at various temperatures in oxygen. The x = 0.5 sample, which was annealed at 800-degrees-C and then quenched, exhibited the highest T(c)(zero resistivity) of 48 K. It was found that there were three different types, two tetragonal phases and one orthorhombic phase, in the "1212" of x = 0.5. It was considered that the phase transformation was caused by different oxygen contents. Samples with a nominal composition of (Pb0.7Cu0.3)Sr2+z(Y0.5Ca0.5-z)Cu2O(y) (z = +/- 0.3) were also prepared. Deviation from z = 0.0 in the composition induced degradation of the superconductivity.