Preparation of YBa_2Cu_3O_7−x precursors from a fused eutectic of sodium and potassium hydroxides

A method for preparing YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} from the simultaneous thermal decomposition of the nitrates of yttrium, barium, and copper in an anhydrous fused eutectic of sodium and potassium hydroxide is described. This method eliminates the need for any mechanical grinding or the introduction of carbon containing anions. Products formed are fine powders ({similar to}1 {mu}m) having mole ratios 1.00 Y:2.00 Ba:3.06 Cu. X-ray diffraction analysis reveal that the initial products are Y(OH){sub 3}, BaO{sub 2}, and CuO, which when air calcinated/ oxygen annealed at 900--950 {degree}C form the superconducting YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}}. A mechanism is postulated for product formation as a function of reaction conditions.