Effect of Ba Substitution for Sr in the Pb-based 1212 Cuprate Containing Sulfur of (PbS)Sr(Y,Ca)CuO.

We already reported on the synthesis of new Pb-based 1212 layered cuprates containing sulfur in the (PbS)Sr(Y,Ca)CuO system. There none of the samples showed superconductivity until after annealing under high O pressure. More recently, we have discovered that the samples could be substituted by Ba for Sr up to x=0.6 in the composition of (PbS)(SrBa)(YCa) CuO. Then if the Ba-substitution is performed for Sr, some of the almost-single phase samples are found to show resistivity drops and magnetic anomalies without annealing under high O pressure. Among the samples, a sample with the nominal composition of (PbS)(SrBa)(YCa) CuO is found to show the highest onset temperatures of a resistivity drop at about 35 K and a magnetic anomaly at about 31.5 K. These are higher than the highest values for the superconducting Ba-free sample of (PbS)Sr (YCa)CuO which was annealed under high O pressure. [ABSTRACT FROM AUTHOR]