Direct Preparation of Fine Powders of the 80 K Superconducting Phase in the Bi-Ca-Sr-Cu-O System by Spray Pyrolysis

Submicron powders of the 80 K superconducting phase in the Bi-Ca-Sr-Cu-O system have been directly prepared by the spray pyrolysis of aqueous solutions of corresponding metal nitrates, Bi:Ca:Sr:Cu=1:1:1:2. The powders obtained were spheres with uniformly distributed diameters below 1 µm. The crystalline phase of these powders was found to greatly depend on the oxygen partial pressure in the carrier gas as well as the decomposition temperature. The preparation conditions for the 80 K superconducting phase were examined.