Critical current density and ultra high-voltage transmission electron microscopic image for melt-processed fine filamentary EuB₂Cu ₃O_x superconductors

We have prepared fine filamentary EuBa₂Cu₃O _x superconductors by solution spinning and melt processing to fabricate the high-T_c superconducting wire with high-critical current density (J_c) at 77 K and high-magnetic fields. The filamentary precursor was partially melted in flowing 0.1% O₂ + Ar and then oxygenated. The samples in diameter of 55 μm had well aligned texture along the filament diameter as well as the length. The T_c value of the sample was 90 K. The transport J_c for the samples was measured at 77 K in applied magnetic fields up to 14T by rotating the sample in a direction of the filament diameter. Anisotropic behaviour of the field dependence of J _c along the filament diameter was detected. The sample rotated the optimized angle exhibited the highest J_c value of 11,000A/cm ₂ at 77K and 14T. The transmission electron microscopic image for the filamentary EuBa₂Cu₃O_x superconductors was observed by using ultra high-voltage transmission electron microscope to clarify the pinning center. Intergrowth of 124-phase and nano-scale particle in the orientated 123 matrix were observed. The presence of such small-scale disorders could improve flux pinning at high fields.