Melting and freezing of Bi-Sr-Ca-Cu-O compounds

High temperature X-ray studies have been carried out for the melting and refreezing of Bi2Sr2Ca1Cu2O8- delta and Bi2Sr2Ca1Cu2O8- delta /Ag composites in order to develop methods to refine the microstructure of these conductors. At least three different insulating phases are stable in the 870 to 890 degrees C temperature range, (Sr,Ca)1Cu,O2, (Sr,Ca)2Cu1O3 and (S,Ca)O. These Bi-poor compounds nucleate and grow on a time scale of a few minutes, but the Bi(2212) supercools a great deal and is not observed to nucleate and grow for periods of an hour at temperatures above 820 degrees C.