SYNTHESIS AND PROPERTIES OF POWDERED OXIDE SUPERCONDUCTOR BY THE MIST PYROLYSIS METHOD

Y-Ba-Cu-O and Bi-Pb-Sr-Ca-Cu-O superconductor powders were synthesized by the mist pyrolysis method. The crystalline phase and morphology of mist-pyrolyzed powders depended on the heating temperature, heating time, and concentration of starting solutions. Superconducting phase of Y-Ba-Cu-O and Bi-Pb-Sr-Ca-Cu-O superconductor (low- T(c) phase) were obtained directly by this method. Sintered body of Y-Ba-Cu-O superconductor obtained by using mist-pyrolyzed powder had a density of above 95% of the theoretical density. The critical temperature (T(c)) of Y-Ba-Cu-O superconductor (T(c) end point) was 90 K and its critical current density (J(c)) was above 230 A/cm2 (at 77 K). The T(c) value of sintered Bi-Pb-Sr-Ca-Cu-O body was increased from 55 K to 103 K, because the low-T(c) phase was converted to high-T(c) phase by the long heat treatment. The optimum J(c) value of Bi-Pb-Sr-Ca-Cu-O sintered body was 172A/cm2 (at 77 K).