Formation and Superconductivity of Single-Phase High-Entropy Alloys with a Tetragonal Structure,ACS Applied Electronic Materials

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Formation and Superconductivity of Single-Phase High-Entropy Alloys with a Tetragonal Structure
ACS Applied Electronic Materials ( IF 4.3 ) Pub Date : 2020-03-23 , DOI: 10.1021/acsaelm.0c00108
Bin Liu _{1,

2,

3} , JiFeng Wu _{1,

2,

3} , Yanwei Cui _{2,

3,

4} , Qinqing Zhu _{1,

2,

3} , Guorui Xiao _{2,

3,

4} , Hangdong Wang ₅ , Siqi Wu ₄ , Guanghan Cao ₄ , Zhi Ren _{2,

3}

Affiliation

High-entropy alloys (HEAs) are random solid solutions consisting of five or more elements arranged in an ordered crystal lattice. So far, however, nearly all the single-phase HEAs have either a cubic or hexagonal structure. Here, we report the observation of a single tetragonal sigma (σ) phase in two series of Ta₅[Mo_35–xW_5+x]Re₃₅Ru₂₀ and [Ta_5+yMo_35–y]W₅Re₃₅Ru₂₀ HEAs up to x = 30 and y = 8, respectively. Meanwhile, these HEAs are discovered to exhibit a fully gapped bulk superconductivity with a maximum T_c of 6.29 K at x = y = 0. T_c decreases monotonically with increasing either x or y, which is mainly due to the weakening of the electron phonon coupling strength. Despite the variation in T_c, the superconducting gap remains essentially unchanged for x ≤ 20 and y ≤ 8, but decreases in magnitude at higher x values. Furthermore, it is found that the stability of single σ-phase HEAs is favored by a high valence electron concentration and correlates well with the electronegativity difference of the constituent elements. Our results not only enlarge the number of possible structural symmetries for HEAs but also help to establish the criteria for single σ-phase formation in these multicomponent systems.

中文翻译：

四方结构单相高熵合金的形成与超导

高熵合金（HEA）是由五个或更多个元素排列成有序晶格组成的随机固溶体。但是，到目前为止，几乎所有的单相HEA都具有立方或六边形结构。在这里，我们报告了在Ta ₅ [Mo _{35– x} W _{5+ x} ] Re ₃₅ Ru ₂₀和[Ta _{5+ y} Mo _{35– y} ] W ₅ Re ₃₅两个系列中观察到一个单一的四方σ（σ）相的情况。Ru ₂₀ HEA直到x = 30和y= 8，分别同时，这些HEA与被发现表现出具有最大完全跳空散装超导Ť _Ç在6.29的K X = Ŷ = 0 Ť _Ç减小单调或者增加X或Ý，这主要是由于电子声子的弱化耦合强度。尽管在变化Ť _Ç，超导间隙仍然基本上无变化X ≤20和ÿ ≤8，但在更高的幅度减小X价值观。此外，发现高价电子浓度有利于单个σ相HEA的稳定性，并且与构成元素的电负性差异良好相关。我们的结果不仅扩大了HEA可能的结构对称性的数量，而且还有助于建立这些多组分系统中单个σ相形成的标准。

更新日期：2020-03-23

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