次世代超電導線材の開発と特性評価 ＩＢＡＤ‐ＰＬＤ法を用いた厚膜ＹＢＣＯ線材の高Ｉｃ化の検討

Abstract

Using a new substrate produced by depositing a self-epitaxial CeO2 cap layer with a pulsed laser deposition (PLD) method on a Gd2Zr2O7 (GZO) buffered Hastelloy tape, which was applied using the ion-beam assisted deposition (IBAD) method, YBa2Cu3O7-δ (YBCO) layers by the PLD method were studied in terms of the delta phi (Δφ), Ra values, amount of existing a-axis oriented crystals, and the critical current, Ic, values of the YBCO coated conductors. To obtain a YBCO coated conductor with high Ic, good in-plane texturing of the CeO2 layer is required. The values of Ic were saturated at a certain critical YBCO thickness, which is thicker with a better Δφ of the CeO2 layer. As the YBCO layer thickness increased, the surface morphology became much rougher. Consequently the surface temperature of the YBCO layer fell and the amount of a-axis oriented crystals in the YBCO increased. To solve this problem, we fabricated YBCO films by multi-layer deposition using the Reel-to-Reel system, which was carried out at different temperatures settings and thus the values of Ic increased.