Formation of Bi-Pb-Sr-Ca-Cu-O Superconductor from Precursors Prepared by the Citrate Method

Abstract

The process of the 2223 phase formation from the precursor prepared by the citrate method was investigated X-ray diffraction, thermal analysis, thermal expansion measurement and SEM/EDX. It was found that Bi(Ca_0.5Sr_0.5)O_z, Ca₂PbO₄, CuO and SrCO₃ coexist before the occurrence of the partial-melt. It was also found that the citrate route accelerates the formation of Bi(Ca_0.5Sr_0.5)O_z, which decreases the partial-melt temperature by about 40K. Powder mixtures of the above coexisting phases prepared by solid-state reaction could be converted via heat-treatment to a product that contained 2223 phase in a volume fraction as high as that of the specimen prepared by the citrate method.