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

With the aim of producing bulk YBa2Cu3Oy (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 NdBa2Cu3Oy 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 Tc 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 (Jc) 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.