The temperature-dependent transport critical current density ( Jc ) behavior of REBa₂Cu₃O_7−δ (REBCO) superconducting tapes with various RE substitutions and combinations has been systematically studied in the temperature range of 4 K–77 K. The measured Jc values were found to be highly in accordance with JcT,B=Jc(0K,B)(1−T/Tc)s with the values of the exponent coefficients s ranging from 1.9 to 2.6 in the magnetic-field range of 1–5 T depending on RE ion(s), revealing the dominative pinning mechanism of flux core pinning. The RE-ionic-radius (r) dependences of JcT,B showed reversed trends for temperatures below and above 50 K, with Jc increasing with r at higher temperatures while it decreased with r at lower temperatures, which was consistent with previously reported results. In particular, the in-field Jc of REBCO tapes at 4 K as a function of r was consistent with the Jc –r trend for low temperatures. We propose to attribute the Jc –r trends to the higher charge carrier density and the lower critical transition temperature ( Tc ) in REBCO films with smaller r. The Gd_0.5Yb_0.5BCO tape with superior Jc at low temperatures exhibited the furthest diversion from the Jc –r trendlines due to enhanced correlated pinning by the high-density of vertically aligned second-phase nanocolumns in the film. The temperature dependence of Jc for REBCO tapes with a larger r was found to be more susceptible to the magnetic field. Meanwhile, the exponent coefficients s showed a more precipitous increase with the increasing magnetic field, partially due to the lack of effective pinning defects, which was also confirmed by the two-dimensional x-ray diffraction patterns and the higher α values. This work contributes to the study of the Jc of REBCO superconducting tapes below 20 K and leads to a deeper understanding of the temperature-dependent Jc behavior of REBCO films with various RE substitutions and combinations. This provides more comprehensive guidelines for the optimization of RE ions in REBCO for applications at specific temperatures and magnetic fields.

中文翻译：

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MOCVD 沉积 REBCO 超导带的传输临界电流密度的温度依赖性


具有各种 RE 取代和组合的 REBa ₂ Cu ₃ O _7−δ (REBCO) 超导带的温度依赖性输运临界电流密度 (Jc) 行为已被研究在4 K~77 K温度范围内进行了系统研究，发现测得的Jc值与JcT高度一致，B=Jc(0K,B)(1−T/Tc)s与指数系数值高度一致在 1-5 T 的磁场范围内，s 的变化范围为 1.9 至 2.6，具体取决于 RE 离子，揭示了磁通芯钉扎的主要钉扎机制。 JcT,B 的 RE 离子半径 (r) 依赖性在低于和高于 50 K 的温度下表现出相反的趋势，Jc 在较高温度下随 r 增加，而在较低温度下随 r 减少，这与之前报道的结果一致。特别是，REBCO 胶带在 4 K 下的现场 Jc 作为 r 的函数与低温下的 Jc-r 趋势一致。我们建议将 Jc–r 趋势归因于 r 较小的 REBCO 薄膜中较高的载流子密度和较低的临界转变温度 (Tc)。 Gd _0.5 Yb _0.5 BCO 带在低温下具有优异的 Jc，由于垂直排列的第二层的高密度增强了相关钉扎，因此表现出与 Jc-r 趋势线最远的偏离。薄膜中的相纳米柱。研究发现，r 较大的 REBCO 磁带的 Jc 的温度依赖性更容易受到磁场的影响。同时，随着磁场的增加，指数系数 s 显示出更急剧的增加，部分原因是缺乏有效的钉扎缺陷，二维 X 射线衍射图和较高的 α 值也证实了这一点。 这项工作有助于研究 20 K 以下 REBCO 超导带的 Jc，并有助于更深入地了解具有各种 RE 替代和组合的 REBCO 薄膜的温度依赖性 Jc 行为。这为 REBCO 中稀土离子在特定温度和磁场下的应用优化提供了更全面的指导。