Crystallization of Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ superconducting filaments produced by gas-jet fiberization

X-ray diffraction and differential thermal analysis techniques have been used to investigate the recrystallization products obtained from various heat treatments of glassy Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ filaments produced by the gas-jet fiberization process. In both Pb-doped and Pb-free samples, the 85 K superconducting phase appears after the formation of a disordered Bi/sub 2/Sr/sub 2/Cu/sub 2/O/sub x/-like intermediate phase at lower temperature. The c-lattice parameter of this phase is substantially smaller than the published values for Bi/sub 2/Sr/sub 2/Cu/sub 2/O/sub x/ and increases as the temperature of the heat treatment increases. After heat treatment at 600 degrees C, a Pb-rich second phase is found together with the 2201-like intermediate phase in the Pb-doped material.