Development of REBCO Coated Conductors by TFA-MOD Method With High Properties in Magnetic Fields

With technological advance of the REBaCuO (RE: Rare Earth elements, REBCO) coated conductors (CC), development of the superconducting applications for its practical use has been carried out recently in various fields. In addition, improvement of the magnetic properties of REBCO CCs makes superconducting devices feasible in the liquid nitrogen. The higher Ic values are required in high magnetic fields by the viewpoint of the requirement in conjunction with the superconducting CCs. Therefore the improvement of the Ic values in the magnetic fields is one of the most important problems to apply them to a device (e.g., NMR, MRI, others). In this work, we investigated the fabrication processing to improve the in-field properties of the YGdBaCuO (YGdBCO) CCs by introduction of artificial pinning centers (APCs). The TFA-MOD method using the batch type furnace for the conversion reaction as a cost effective process to fabricate REBCO CCs was improved by adopting the interim heat treatment during the ramp step of the conversion reaction. The improvement of the properties by the improved process was remarkable and the advanced CCs were named as nPAD-YBCO. A 124 m-long nPAD-YBCO consisted of YGdBCO CC with BZO nano particles was successfully fabricated, exhibiting the I_cmin > 50 A/cm-w @77 K, 3 T (I_c: Critical current) throughout the conductor. Analyzing the characteristics of the conductor, the BZO particles introduced into the YGdBCO layer worked as effective APCs in wide ranges of temperature and magnetic fields.