Continuous Fabrication of YBCO Tapes with YSZ Textured Buffers by the IBAD Method

Abstract

Long flexible tapes with high-transport critical current density (J_c) are needed for the application of HTS to electric power technology. YBCO retains high J_c in high magnetic fields at 77K because of its strong pinning property. Recently, YBCO tapes are considered to be the second generation of HTS wire, and several groups have succeeded in the fabrication of YBCO tapes on metallic substrates of about 1m in length. We also continuously fabricated long and high J_c YBCO film tapes on flexible Ni-based alloy (width: 10mm, thickness: 0.1mm). Biaxially aligned YBCO films were deposited by pulsed laser deposition (PLD) on textured YSZ buffer layers formed using ion-beam-assisted deposition (IBAD). Uniform textured YSZ buffer layers were demonstrated at the length of 3m. Consumption of the YBCO target was controlled by scanning a YBCO target in the PLD process. The reduction ratio of the film thickness after 9h was controlled within about 10%. Y₂O₃ second-buffer layers were deposited for the purpose of preventing the interface reaction and lattice mismatch between YBCO/YSZ. A J_c value of 2.4×10⁵A/cm² and I_c value of 25.3A were obtained at 77K, 0T over the whole length of 2.1m.