A Novel Synthetic Method for the Preparation of Oxide Superconductors.

A novel chemical method for the preparation of Ba sub 2 YCu sub 3 O sub 7 is described, and is applicable to the synthesis of other superconducting oxides. Ionic salt precursors are used whose oxidation-reduction chemistry converts the precursors into their mixed oxides at low temperatures. A solution containing nitrate and acetate salts is spray dried to form a uniformity mixed powder. Because the nitrate salts are potent oxidizers, they participate in an oxidation-reduction (redox) reaction. The exothermic redox reaction, and the heat evolved from the reaction, completely convert the precursors into their corresponding mixed oxides at temperatures as low as 270C, which constitutes an improvement of at least 130C over the decomposition temperatures of the acetate or nitrate salts alone. Nearly single phase (95%) Ba sub 2 YCu sub 3 O sub x can be produced at a temperature of 910C in 5-10 minutes.