PREPARATION OF BI-PB-SR-CA-CU-O SUPERCONDUCTOR BY THE CITRATE METHOD

The high-T, 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 673 K for lh to decompose organic substances. After being pulverized and pelletized, the samples were sintered at 1133 K for 5h. By repeating the above procedure exactly and allowing to cool in the furnace at a rate of 0.5 K/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 101 K.