Pressure-Effect Study on the High-T_c Superconductor Bi(Pb)-Sr-Ca-Cu-O System

Abstract

Transiton temperatures ( T c ) and lattice constants of Bi(Pb)-Sr-Ca-Cu-O superconductors have been determined by a magnetic susceptibility measurement and a high-pressure X-ray diffraction measurement as a function of pressure. The T c of the high- T c phase increases monotonically with an increase in pressure up to 4.5 GPa. The initial coefficient is 2.0 K/GPa, which agrees with that of the low- T c phase reported previously. The linear compressibility along the c -axis direction, which is parallel to the bonding direction between the Cu atom and the apical oxygen, shows the same value for both phases.