Low-angle grain boundaries (GBs) constitute the most important current-limiting mechanism in the operation of biaxially textured YBa₂Cu₃O_7−d (YBCO)-coated conductors. Ca doping of YBCO is known to improve the critical current density J _c across the GB because of carrier doping by anisovalent Ca²⁺ substitution for Y³⁺ and the strain relief induced by Ca segregation at the GB cores; however, the reduction of the superconducting critical temperature T _c accompanying such doping is a marked drawback. Here we study the substitution of isovalent Nd³⁺ for Y³⁺ again using strain-driven segregation, in this case Nd³⁺, to improve J _c without incurring significant T _c reduction. Transport characteristics of low-angle GBs of 10% Nd-doped YBCO, Y_0.9Nd_0.1Ba₂Cu₃O_7−d, grown on single crystal and 6 and 9 [001] tilt symmetric bicrystal SrTiO₃ substrates are reported. It was found that J _c across the 6 GB recovers to the intra-grain J _c value in the 10% Nd-doped YBCO, while the 9 GB shows a modest J _c enhancement compared to the pure YBCO 9 GB without a significant T _c reduction. It is shown that the transparency of the GB could be enhanced without a large T _c reduction by the isovalent substitution of rare-earth ions, suggesting new opportunities for cation segregation engineering in YBCO by isovalent rare-earth substitution.

在双轴织构YBa ₂ Cu ₃ O _7-d（YBCO）涂覆的导体的操作中，低角度晶界（GBs）构成了最重要的限流机制。已知YBCO的Ca掺杂可改善GB上的临界电流密度J _c，这是因为通过Y ³⁺的异质Ca ²⁺取代引起的载流子掺杂以及GB核心处Ca偏析引起的应力消除。然而，伴随这种掺杂的超导临界温度T _c的降低是明显的缺点。在这里，我们研究了等价的Nd ³⁺替代Y ³⁺ 再次使用应变驱动的隔离（在这种情况下为Nd ³⁺）来提高J _c，而不会显着降低T _c。报道了生长在单晶和6和9 [001]倾斜对称双晶SrTiO ₃衬底上的10％掺Nd的YBCO，Y _0.9 Nd _0.1 Ba ₂ Cu ₃ O _7-d的低角度GBs的传输特性。发现在6 GB的J _c恢复到掺Nd含量为10％的YBCO中的晶粒内J _c值，而9 GB的J _c恢复为中等 与纯YBCO 9 GB相比增强了，而T _c却没有明显降低。结果表明，通过稀土离子的等价取代，可以在不大幅降低T _c的情况下提高GB的透明度，这表明通过等价稀土取代在YBCO中进行阳离子分离工程的新机会。