Behavior of Two Oxide Superconductors under High Pressure

The high-pressure observations at low, normal and high temperature have been performed on two single-phased superconducting oxides, NdBa2Cu3Ox and (Bi,Pb)2Sr2Ca2Cu3Oy, respectively. The superconducting transition temperatures were all raised with increasing pressure. It was noted that the normal state resistances increased abruptly (then down again) near 1.0 GPa in both of the superconductors corresponding to a gentle step of the increasing Tc. The high-pressure DTA for NdBa2Cu3Ox showed that the transition from high temperature tetragonal phase to superconducting orthogonal phase is advanced, which indicates that the high pressure is advantageous to the stability of the superconducting phase structure.