EFFECT OF Y2BACUO5 PARTICLE-SIZE ON THE PROPERTIES OF YBA2CU3O7-X SUPERCONDUCTOR

YBa2Cu3O7-x (123) bulk superconductor, which contained uniformly dispersed fine Y2BaCuO5 (211) grains, was fabricated with pre-synthesized Y2BaCuO5, BaO2 and CuO powders by a partial melting process. The size reduction of pre-synthesized 211 powders by fine grinding and low temperature calcination had a positive effect on the homogeneous distribution of the fine 211 grains in superconductor bulk materials. The critical current density, J(C), in a magnetic field increased approximately in proportion to the total surface area of 211 grains per unit weight in the 123 phase. When the magnetic field increased, the increase of J(C) with the increase of surface area of 211 grains became steep.