Crystallization behavior and partially melted states in Bi-Sr-Ca-Cu-O

High-temperature X-ray measurements were carried out on Bi-Sr-Ca-Cu-O. It was found that the 30 Å phase showed incongruent melting forming new crystalline phases which differed depending on the compositions. Crystallization from the melt by cooling first produced the 30 Å phase on solidification and then the 24 Å phase crystallized around 730°C. Crystallization from the glassy phase by heating started at 430°C and led to the 24 Å phase, which changed to the 30 Å phase above 800°C. As a rule, low-temperature crystallization from the amorphous phase takes place below 730°C to form the 24 Å phase in Bi-Sr-Ca-Cu-O.