Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6116, USA.
Sci Rep. 2013;3:2310. doi: 10.1038/srep02310.
We report microstructural design via control of BaZrO3 (BZO) defect density in high temperature superconducting (HTS) wires based on epitaxial YBa2Cu3O7-δ (YBCO) films to achieve the highest critical current density, Jc, at different fields, H. We find the occurrence of Jc(H) cross-over between the films with 1-4 vol% BZO, indicating that optimal BZO doping is strongly field-dependent. The matching fields, Bφ, estimated by the number density of BZO nanocolumns are matched to the field ranges for which 1-4 vol% BZO-doped films exhibit the highest Jc(H). With incorporation of BZO defects with the controlled density, we fabricate 4-μm-thick single layer, YBCO + BZO nanocomposite film having the critical current (Ic) of ~1000 A cm(-1) at 77 K, self-field and the record minimum Ic, Ic(min), of 455 A cm(-1) at 65 K and 3 T for all field angles. This Ic(min) is the largest value ever reported from HTS films fabricated on metallic templates.
我们通过控制基于外延 YBa2Cu3O7-δ（YBCO）薄膜的高温超导（HTS）线材中 BaZrO3（BZO）的缺陷密度来实现微观结构设计，以在不同场强 H 下获得最高临界电流密度 Jc。我们发现，BZO 掺杂量为 1-4 体积%的薄膜之间出现了 Jc（H）交叉，这表明最佳 BZO 掺杂强烈依赖于场强。通过 BZO 纳米柱的数密度估算出匹配场强 Bφ，与 1-4 体积% BZO 掺杂薄膜表现出最高 Jc（H）的场强范围相匹配。通过控制密度引入 BZO 缺陷，我们制备出了 4-μm 厚的单层 YBCO + BZO 纳米复合材料薄膜，在 77 K、自场下的临界电流（Ic）约为 1000 A cm(-1)，在 65 K 和 3 T 下所有场角的最小临界电流 Ic(min)为 455 A cm(-1)。这是有史以来在金属模板上制备的 HTS 薄膜中报道的最大 Ic(min)值。
