Formation of the High-Tc Phase in Rapidly Quenched Bi-Pb-Sr-Ca-Cu-O Ceramics

Abstract

Amorphous ceramics with the composition of Bi2Pb0.4Sr2Ca2Cu3Oy were prepared by rapid quenching. The change in crystalline structure during annealing and the effect of the “seeding” with the high-Tc phase were investigated. The volume fraction of the high-Tc phase increases with annealing time; however, the low-Tc phase reaches a maximum value of 38% for 1 h annealing and decreases on prolonged annealing. The formation rate of the high-Tc phase changes when the volume of the high-Tc phase reaches about 30%. TEM observation shows that the high-Tc phase is often located between the low-Tc phase and the nonsuperconducting phase. The addition of the seed crystals with the high-Tc phase is effective in forming the high-Tc phase in shorter annealing times, but a smaller volume fraction of the high-Tc phase was obtained after annealing for 50 h.