FORMATION OF BI-PB-SR-CA-CU-O SUPERCONDUC TOR FROM PRECURSORS PREPARED BY THE CITRATE METHOD

The process of the 2223 phase formation from the precursor prepared by the citrate method was investigated by X-ray diffraction, thermal ana lysis, thermal expansion measurement and SEM/EDX. It was found that Bi (Ca0.5Sr0.5) O(z), Ca2PbO4, CuO and SrCO3 CoeXist before the occurren ce of the partial-melt. It was also found that the citrate route accel erates the formation of Bi (Ca0.5Sr0.5) O(z), which decreases the part ial-melt temperature by about 40 K. Powder mixtures of the above coexi sting phases prepared by solid-state reaction could be converted via h eat-treatment to a product that contained 2223 phase in a volume fract ion as high as that of the specimen prepared by the citrate method.