Development of high critical current density YBCO high temperature superconducting round wire

Abstract

YBa₂Cu₃O_7-ẟ (YBCO) round wires with high critical current density (J_c) were developed by the Powder—in—Tube method and melt—growth process. For the sheath material of the wire, silver was selected since it doesn’t react with YBCO, it is not oxidized at high temperatures in the air, and it is permeable to oxygen. Since BaCu₂O₂ has a melting point of 880°C, which is lower than silver, BaCu₂O₂ and Y₂BaCuO₅ were prepared as raw materials. The YBCO round wire was developed by melt-growth process in oxygen pressure control condition. After the heat-treatment, large YBCO grains were observed. The critical current density of the wire reached 46 kA⁄cm² at 4.2 K in self-field and 33 kA⁄cm² in 14 T. Unfortunately, since current sharing through the silver occurred during the measurements, the exact Ic should be evaluated.