Preparation of Superconducting Bi₂Sr₂CaCu₂O_x Ceramics by Low-Temperature Heat Treatment

Abstract

Superconducting ceramic rods ( T c ≈80 K) of Bi 2 Sr 2 CaCu 2 O 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 Bi 2 Sr 2 CuO x (2201 phase) and small amounts of Cu 2 O and unidentified crystalline phases.