Synthesis of the 107 K Superconducting Phase in the Bi-Sr-Ca-Cu-O System

Synthetic conditions of the 107 K superconducting phase in the Bi-Sr-Ca-Cu-O system were investigated to obtain a pure ceramic material of the 107 K phase. From the starting materials identical to compositions of the 107 K phase, the 80 K phase was prepared as a predominant metastable phase. For the formation of a large fraction of the 107 K phase, kinetic conditions such as the presence of a small amount of liquid phase, special bulk compositions, special temperatures and long heating times become the important factors, although the 107 K phases showed large compositional variations and were stable at least at 870–900°C in air.