Synthesis of 110 K Bi(Pb)-Sr-Ca-Cu-O Oxide Superconductors

Abstract

The synthesis of high-T _c Bi(Pb)-Sr-Ca-Cu-O superconductors is reported in this Letter. Zero resistance is attained at 110 K for the samples sintered at 845°C for 200–300 h. The best sample is obtained after 300 h sintering. The d c magnetic susceptibility measurement shows the presence of 53% of a high-T _c phase and 4% of a low-T _c phase in terms of the sample-volume ratio. The T _c decreased from 110 K to 108 K after a few days, suggesting that the T _c=110 K state is metastable. The synthesis of the high-T _c phase is studied from the viewpoint of sintering time, gas atmosphere, quenching and annealing procedures, and the Pb content in the original mixed materials.