Abstract
A relationship between synthesized phases and starting compositions has been studied in the Pb-Bi-Sr-Ca-Cu-O system. The reaction step of forming the high-Tc phase (Tc∼110 K) has been presumed as follows. Firstly, the high-Tc phase and Bi2Sr2CuOx are obtained from the disproportionation reaction of the low-Tc phase. Bi2Sr2CuOx and residual Ca and Cu atoms melt into the PbO flux. The low-Tc phase is precipitated from the melt. The formed low-Tc phase causes a further disproportionation reaction. The high-Tc phase is produced in large quantities by repeating the cycle.