Abstract
The effect of a sintered density (open porosity) of Y(2)BaCuO(5) (Y211) pre-forms on the final porosity and Y211 size within YBa(2)Cu(3)O(7-y) (Y-123) products was systematically studied in liquid infiltration growth (LIG) processed Y-123 bulk superconductors with Ag addition. To prepare Y211 pre-forms of various densities, Y211 powder compacts were sintered in air at various temperatures of 900-1200 degrees C. The single-grain Y-123 bulk superconductors were fabricated by the LIG process with top seeding. It was found that the porosity of the final Y-123 product was fairly dependent on the Y211 pre-form density. When a Y211 pellet of a high density was used as a pre-form for the LIG process, the porosity of the final Y-123 product was greatly reduced. In addition to the reduced porosity, the enhanced Y211 refinement was achieved for the Y-123 product prepared using the dense Y211 pre-form, resulting in the improved critical current density (J(c)). The Ag addition was also helpful in eliminating the spherical pores through pore filling with a silver melt. The pore elimination and Y211 refinement mechanism in the LIG-processed Y-123 bulks were explained in terms of the liquid capillary movement and Ag melt and particle coarsening at the (Y211 + melt) state.