Microstructural Nonuniformity of GdBCO Superconductor Bulk

Abstract

High-temperature superconducting materials REBa2Cu3O7-δ(REBCO or RE123, RE is a rare earth), can widely be used in electric motors, nuclear magnetic resonance and other fields, because these can trap strong magnetic fields. The top-seeded melt-texture growth method is widely chosen in the preparation and performance research of various REBCO superconductor bulks, which can effectively suppress random nucleation and reduce weak connections between grains, etc. However, the superconductor bulks prepared by this method often have the problem of uniformed microstructure. A single-domain GdBCO superconductor bulk with NdBCO single-seed guidance and Y123 liquid source was successfully growth using the top-seeded melt-texture growth method, and the microscopic morphology of the samples were studied, which exhibits the microstructural nonuniformity of GdBCO superconductor bulk. The specimens at different positions, C1, C2 below the seed, P1, P2 below the cross pattern, of the bulk exhibit critical transition temperature, TC , higher than 94.5 K, with a maximum value of 95.9 K, demonstrating superior superconductivity. Cracks and pores are unevenly distributed in GdBCO superconductor bulk, and the pores mainly gather in the area below the seed and far from the upper surface. At the same distance from the upper surface, specimens below the cross pattern have higher self-field JC values (P1>C1, P2>C2) than specimens below the seed, which should be related to the nonuniformity of the pores.