Effects of densification of precursor pellets on microstructures and critical current properties of YBCO melt-textured bulks

Highlights: • YBCO bulk superconductors were fabricated from densified precursor disks. • Densification of precursor disks led to the decrease in residual voids for bulks. • YBCO melt-textured bulks with low porosity exhibited high J_c in magnetic fields. • Vortex states in YBCO bulks can be possibly affected by their porosity. - Abstract: Effects of densification of precursor disks on the density of residual voids and critical current properties for YBCO melt-textured bulk superconductors were systematically investigated. Six YBCO bulks were prepared from precursor pellets with different initial particle sizes of YBa₂Cu₃O_y (Y123) powder and applied pressures for pelletization. It was revealed that use of finer Y123 powder and consolidation using cold-isostatic-pressing (CIP) with higher pressures result in reduction of residual voids at inner regions of bulks and enhance J_c especially under low fields below the second peak.