Sharp edged Gd₂BaCuO₅particles addition effect on growth and properties of top-seeded melt-grown GdBa₂Cu₃O_7-δ bulk superconductors

We report on top-seeded melt growth of GdBa2Cu3O7-δ (GdBCO) bulks added by sharp edged Gd2BaCuO5 nanoparticles (Gd211U) refined by ultrasonication. GdBCO bulks mixed with 30 mol.% of Gd211U were examined to be grown isothermally at different temperatures in a range of 1015 °C-1035 °C using a top-seeded melt growth technique. Magnetic susceptibility measurements show that all samples become superconducting and especially samples grown at 1020°C and 1025°C have a maximum superconducting transition temperature (T c) of 94.5 K. The critical current density (J c) obtained from magnetic hysteresis loops for magnetic fields parallel to the c-axis is up to 65100 A/cm2 (the self-field at 77 K) for a sample grown at 1025 °C, while J c of a GdBCO bulk with conventional Gd211 particles grown at 1025 °C for comparison is 29000 A/cm2 (the self-field at 77 K).