Preparation of high Tc superconducting wire by precursor spinning method.

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For practical application of high T_c superconducting magnet at 77K,the superconducting wire with high J_c at high magnetic field is needed. We have studied the preparation of the filamentary superconducting oxide using a textile fiber spinning technology for the precursor of the oxide.Long precursor filaments were prepared by dry spinning with a starting homogeneous aqueous poly vinyl alcohol solution containing Y or Nd, Ba and Cu acetates. The as-drawn filament with diameter of 250mum was pyrolyzed to remove the volatile components and heated to generate a superconducting phase. By controlling the spinning process and partially melted treatment in O_2 flow, maximum J_c value of more than 10^5A/cm^2 at 77K and 0T was attained for the filamentary Y123 superconductor.A Y123 superconducting filament of 60mum in diameter and 200mm in lenth with high J_c of more than 10^4A/cm^2 was obtained by controlling the heating process.The oxygen controlled melt growth of the Nd123 precursor filament was examined. The field dependence of the transport J_c of the filamentary Nd123 superconductor was better than that for the Y123 superconductor and more than 10^3A/cm^2 at 77K and 10T was achieved for the filamentary Nd123 superconductor partially melted in 1%O_2+Ar flow. The fabrication of multifilamentary Y123 superconducting composite was made by using the silver paste and a composite with high superconducting and mechanical propeties was prepared.