By studying the Bi-Pb-Sr-Ca-Cu-O system, we have found that the sintering time to form high Tc Bi-Pb-Sr-Ca-Cu-O systems was quite different as the compositions of the starting materials varied. Especially, the ratio of Sr/Ca played an important role in determining the sintering time.
DTA study already showed that partial melting occurred during the reaction. The temperature of the partial melting was also related to the ratio of Sr/Ca. Our results supported the existence of a reactive liquid phase in sintering process.