PREPARATION OF BA0.6K0.4BIO3 PURE SUPERCONDUCTING POWDER

Propionate precursors have been used for the preparation of supercondu cting phase. The formation of perovskite phases has been studied under inert gas and oxygen during heat treatment. X-ray diffraction and mag netic susceptibility measurements have been carried out at different s tages of the three steps process of synthesis. BaBiO3 with unreacted B i2O3 and KBiO2 appears under oxidizing treatment near 700-degrees-C. P erovskite intermediate phases Ba0.87K0.13BiO3 (cubic; a=4.322 angstrom ) and Ba0.6K04BiO2.3 (tetragonal; a=4.292 angstrom, c=4.539 angstrom) are observed during second step under neutral gas. These compounds are not superconducting. Final annealing under oxygen at 400-degrees-C le ads to superconducting phase. Grain surface area is related to the rea ction speed. Pure superconducting Ba0.6K0.4BiO3 powder has been prepar ed.