Preparation of Superconducting Bi2Sr2CaCu2Ox Ceramics by Low-Temperature Heat Treatment

Abstract
Superconducting ceramic rods (T c≈80 K) of Bi2Sr2CaCu2O x were successfully prepared by heat treatment in air at 700°C for 20-50 h; the temperature of 700°C is believed to be the lowest temperature reported so far. The precursor rod specimens were made by vacuum casting the stoichiometric melts into silica tubes; the as-cast rods are spontaneously devitrified during cooling and are composed of crystalline phases of Bi2Sr2CuO x (2201 phase) and small amounts of Cu2O and unidentified crystalline phases.