Microstructure and properties of superconducting Bi-Pb-Sr-Ca-Cu-O synthesised by the alkoxy sol-gel method

It is well established that the Bi-Sr-Ca-Cu-O high Tc compound consists of two superconducing phases: The 110 K phase with the composition Bi2Sr2Ca2Cu3O10 (2223 phase) and the 80 K phase corresponding to Bi2Sr2Ca1Cu2O8 (2212 phase). Although this system is less sensitive to the oxygen stoichiometry than YBCO, a careful processing including a long reaction time and a precise temperature control is essential in obtaining the higher-Tc phase. Partial substitution of Bi by Pb further enhances the formation and stabilisation of the high-Tc phase. In this paper we report on the synthesis, microstructure and superconducting properties of the 110 K and 80 K Bi-Pb-Ca-Cu-O phases prepared by the alkoxy sol-gel method. (orig.)