Hip Treatment on the Bi-Pb Oxide High-Tc Superconductor

It is well known that HIP treatment provides highly densified ceramics. The influences of HIP treatment on the densification of the Bi-Pb high-Tc ceramics and the electrical conductivity have been studied on the sample with a nominal composition of Bi_0.96Pb_0.24Sr_1.0Ca_1.1Cu_1.6O_x. It was found that tlle density of the sample was attained over 90% of the theoretical density of the Bi-Pb high-Tc phase by the HIP treatment at 850°C for 2h. While the electrical resistance of the sample without HIP treatment decreased in linear with decreasing temperature from 280K to 120K and dropped to zero near 100K within the experimental limit, that of the HIP treated sample increased semiconductively between the temperature range from 280K to 110K, and below 110K gradually dropped to zero at 60-70K. However, the degradation of the HIP treated sample in the electrical conductivity was recovered by the heat treatment at 850°C for 48h in air. This behavior in the electrical conductivity seems to be associated with the precipitation of Ca₂PbO₄ in the grain boundary and the deficient of oxygen in the high-Tc phase.