Local structure in high-entropy transition metal diborides
Local structure in high-entropy transition metal diborides
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DOI：
10.1016/j.actamat.2022.118294
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发表时间：
2022-08
期刊：
影响因子：
9.4
通讯作者：
M. Gaboardi;F. Monteverde;F. Saraga;G. Aquilanti;Lun Feng;W. Fahrenholtz;G. Hilmas
中科院分区：
文献类型：
--
作者：
M. Gaboardi;F. Monteverde;F. Saraga;G. Aquilanti;Lun Feng;W. Fahrenholtz;G. Hilmas
对高熵材料的研究经常推测晶格扭曲和无序对诸如硬度、热膨胀和电子性质等特性的影响。尽管正在进行发现新成分的竞赛，但在原子水平上对局部结构的调查充其量仍是稀少的。此外，对晶格位置内金属分布的均匀性的评估通常限于诸如能量色散光谱之类的技术，这可能导致对大块材料的不准确的描述。在这里，我们报告了一类新兴的高熵陶瓷的广泛和系统的研究，这种陶瓷结合了高分辨率同步辐射粉末衍射和扩展的X射线吸收精细结构分析。我们的数据与原子在这些金属位置周围具有局部应变的随机分布是一致的，这描述了这些材料的整体结构。此外，无论构成高熵陶瓷的金属的数量(从3到5)和类型(Ti，Zr，Nb，Hf，Ta，Mo，W)如何，平均结构与第一邻近距离之间都存在线性趋势，这表明对这类材料的性质的任何描述都需要超越长程有序和局域结构的简单二分法。
Studies on high-entropy materials often speculate about the effects of lattice distortion and disorder on characteristics such as hardness, thermal expansion, and electronic properties. Notwithstanding the ongoing race to discover new compositions, investigations of the local structure at the atomic level remain sparse at best. Additionally, assessments of the homogeneity of the distribution of metals within the lattice sites are often restricted to techniques such as energy dispersive spectroscopy which might lead to an inaccurate picture of the bulk material. Herein, we report an extensive and systematic study of a class of emerging high-entropy ceramics that uses a combination of high-resolution synchrotron powder diffraction and extended X-ray absorption fine structure analysis. Our data are consistent with a random distribution of atoms with local strain around thed-metals sites, which describes the bulk structure of these materials. Moreover, a linear trend is observed between the average structure and the first-neighbour distances, regardless the number (from 3 to 5) and type (Ti, Zr, Nb, Hf, Ta, Mo, W) of metals that constitute the high-entropy ceramic, which suggests that any description of properties for such materials need to go beyond the simple dichotomy of long-range order and local structure.