Preparation of Bi-Pb-Sr-Ca-Cu-O Superconductor by the Citrate Method

Abstract

The high-T_c Bi-Pb-Sr-Ca-Cu-O superconductor (2223 phase) has been prepared by a citrate method. The processing parameters to give the largest amount of 2223 phase were found as follows. The precursor gel powders were first heated at 673K for 1h to decompose organic substances. After being pulverized and pelletized, the samples were sintered at 1133K for 5h. By repeating the above procedure exactly and allowing to cool in the furnace at a rate of 0.5K/min, the superconductor, in which the maximum volume fraction of high T_c-2223 phase attained 89%, was successfully obtained. This value is much greater than that in samples obtained by the conventional solid-state reaction method under the same heat treatment conditions. The zero resistance temperature of the superconductor thus obtained was 101K.