Processing and microstructure of single grain, uranium-doped Y-Ba-Cu-O superconductor

Large grain Y-Ba-Cu-O (YBCO) superconductor doped with various amounts of depleted UO2 and containing excess Y2BaCuO5 (Y-211) and Y2O3 have been fabricated by top seeded melt growth (TSMG). The effect of depleted UO2 on the large grain microstructure has been studied systematically in samples with and without added Pt. It is found that UO2 refines the size of the second phase particles in the superconducting YBa2Cu3O7-delta (Y-123) matrix to dimensions of a few hundred nanometres with an approximately spherical morphology. Addition Of Y2O3 to the uranium-doped precursor powder, rather than Y-211, yields a significantly finer distribution of second phase particles and an associated higher critical current density J(c) at increased magnetic field.