论文标题
Sigesn中等渗透合金中两种类型的短期顺序共存
Coexistence of two types of short-range order in SiGeSn medium-entropy alloys
论文作者
论文摘要
最近已证明短距离化学秩序（SRO）在调节中等凝集合金（MEA）和高渗透合金（HEA）中的广泛物理特性方面起着决定性的作用。这些合金的巨大配置空间暗示SRO的多种形式可能会同时发展，但尚未报道这种结构多样性。在这里，我们通过基于广泛的{\ em ab intio}的抽样研究表明，Sigesn中等渗透合金自发地开发了两种不同的SRO形式。值得注意的是，发现具有不同能量的两种类型的SRO，不同程度的局部排序和不同的电子结构，可以共存于广泛的Sigesn合金组成中。两个SRO的共存是通过热力学稳定性的虚拟退化而合理化的，这是由于两个SRO之间转换的焓变和构型熵的变化的微妙平衡。因此，这种SROS的这种共存表明了Sigesn MEA中固有的结构异质性，弥漫性电子结构和新的带工程途径。更普遍地，我们的发现表明，多种形式的SRO在广泛的测量和HEAS中的共存可能存在无处不在，这对它们的多样化物理特性具有深远的影响。
Short-range chemical order (SRO) has been recently demonstrated to play a decisive role in modulating a wide range of physical properties in medium-entropy alloy (MEA) and high-entropy alloy (HEA). The enormous configurational space of these alloys implies multiple forms of SRO are likely to develop concurrently but such structural diversity has not been reported. Here we show, through extensive {\em ab initio}-based sampling study, that SiGeSn medium-entropy alloys spontaneously develop two distinct forms of SRO. Remarkably, the two types of SROs, which carry different energies, distinct degrees of local ordering, and dissimilar electronic structures, are found to co-exist in a wide range of compositions of SiGeSn alloys. The co-existence of two SROs is rationalized through their virtual degeneracy of thermodynamic stability, due to the subtle balance in the change of enthalpy and configurational entropy upon the transformation between the two SROs. Such co-existence of SROs thus suggests an inherent structural heterogeneity, a diffuse electronic structure, and a new route for band engineering in SiGeSn MEA. More generally, our finding indicates the possible ubiquity of the co-existence of multiple forms of SRO in a broad range of MEAs and HEAs, which has profound implications on their diverse physical properties.
