Cayado Pablo, Grünewald Lukas, Erbe Manuela, Hänisch Jens, Gerthsen Dagmar, Holzapfel Bernhard
Karlsruhe Institute of Technology (KIT), Institute for Technical Physics (ITEP) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
University of Geneva, Department of Quantum Matter Physics (DQMP) Quai Ernest-Ansermet 24 1211 Geneva Switzerland.
RSC Adv. 2022 Oct 11;12(44):28831-28842. doi: 10.1039/d2ra03807b. eCollection 2022 Oct 4.
High-entropy oxide (HEO) superconductors have been developed since very recently. Different superconductors can be produced in the form of a high-entropy compound, including REBaCuO (REBCO). However, until now, mainly bulk samples (mostly in polycrystalline form) have been reported. In this work, the first CSD-grown high-entropy (HE) REBCO nanocomposite films were successfully synthesized. In particular, high-quality GdDyYHoErBaCuO nanocomposite films with 12 mol% BaHfO nanoparticles were grown on SrTiO substrates. The X-ray diffraction patterns show a near-perfect -axis oriented grain growth. Both and 77 K , 91.9 K and 3.5 MA cm, respectively, are comparable with the values of the single-RE REBCO films. Moreover, at low temperatures, specifically at 30 K, the values are larger than those of the single-RE samples. A transmission electron microscopy (TEM) study, including energy-dispersive X-ray spectroscopy (EDXS) measurements, reveals that the different RE ions are distributed homogeneously in the matrix without forming clusters. This distribution causes point-like pinning centres that explain the superior performances of these samples at low temperatures. Although still seen as a proof-of-concept for the feasibility of preparing such films, these results demonstrate that the HE REBCO films are a promising option for the future fabrication of high-performance coated conductors. In the investigated - range, however, their values are still lower than those of other, medium-entropy REBCO films, which shows that an optimization of the composition of the HE REBCO films is needed to maximize their performance.
高熵氧化物（HEO）超导体是最近才开始研发的。不同的超导体可以制成高熵化合物的形式，包括稀土钡铜氧化物（REBCO）。然而，到目前为止，主要报道的是块状样品（大多为多晶形式）。在这项工作中，首次成功合成了化学溶液沉积（CSD）生长的高熵（HE）REBCO纳米复合薄膜。具体而言，在钛酸锶（SrTiO）衬底上生长了含有12摩尔% 钡铪氧化物（BaHfO）纳米颗粒的高质量钆镝钇钬铒钡铜氧化物（GdDyYHoErBaCuO）纳米复合薄膜。X射线衍射图谱显示出近乎完美的c轴取向晶粒生长。零场冷却（ZFC）和77 K时的临界电流密度（Jc）分别为91.9 K和3.5 MA/cm²，与单一稀土REBCO薄膜的值相当。此外，在低温下，特别是在30 K时，Jc值比单一稀土样品的Jc值更大。包括能量色散X射线光谱（EDXS）测量在内的透射电子显微镜（TEM）研究表明，不同的稀土离子均匀分布在基体中，没有形成团簇。这种分布产生了点状钉扎中心，这解释了这些样品在低温下的优异性能。尽管这些结果仍被视为制备此类薄膜可行性的概念验证，但它们表明HE REBCO薄膜是未来制造高性能涂层导体的一个有前景的选择。然而，在所研究的温度范围内，它们的Jc值仍低于其他中熵REBCO薄膜的Jc值，这表明需要优化HE REBCO薄膜的成分以使其性能最大化。
