Fabrication of bulk Y-Ba-Cu-O superconductors with high critical current densities through the infiltration-growth process

With the aim of producing bulk YBa₂Cu₃O_y (Y123) superconductors with high flux pinning performance, we employed an infiltration growth (IG) process, in which liquid phase Ba-Cu-O is infiltrated into Y₂BaCuO₅ (Y211) pellets with NdBa₂Cu₃O_y seed at high temperatures to produce Y123 phase. Single grain Y123 samples 27 mm in diameter and 5 mm in thickness could be produced with the seeded IG method. Trapped field measurements showed that the IG-processed Y123 sample was a single domain with the maximum trapped field of around 0.403 T at 1 mm above the surface at 77 K. Magnetization measurements demonstrated that IG-processed Y123 sample exhibits a sharp superconducting transition with an onset T_c of around 93.2 K. Microstructural observations by means of atomic force microscopy (AFM) clarified that sub-micrometer-sized Y211 particles are finely and uniformly distributed in the Y123 matrix, which is the source of high pinning performances. The critical current density (J_c) values at liquid nitrogen temperature (77 K) and 50 K in 0 T were 1.75 × 10⁵ A/cm² and 5.28 × 10⁵ A/cm², respectively. These values are the highest among bulk Y123 samples ever reported in the literature.