Preparation of superconducting YBa2Cu3O7-x compounds by water extraction variant of sol-gel process

This paper reports on the staring sols prepared by addition of ammonium hydroxide to acidic solutions of Y-Ba-Cu acetates or by dissolving solid BaCO3 or CuCO3 · Cu(OH)2 · H2O in acetates of the remaining components. The sols were then gelled to spherical particles with diameter below 50μm by extracting water with 2-ethyl-1-hexanol or to shard by evaporation of water. After thermal treatment of both powders amorphous and then crystalline YBa2Cu3P7-x were obtained. Formation of these compounds is strongly improved by aging the gel at 200 degrees C. Green and sintered pellets exhibit excellent superconductivity properties