Defects exert a profound influence on thermoelectric materials by altering electronic band structures and significantly impacting their performance. Despite being a potentially promising thermoelectric material, the mechanism behind defect formation in half-Heusler (HH) compounds ABX remains unclear, impeding the enhancement of their thermoelectric properties. In this study, we investigated the intrinsic defect formation energies for ANiSb (A = Sc, Y, Er) and other 9 HH compounds, namely ANiSn (A = Ti, Zr, Hf), AFeSb (A = V, Nb, Ta), and ACoSb (A = Ti, Zr, Hf), using first-principles calculations and thermodynamics. The results reveal that ANiSb (A = Sc, Y, Er) exhibits anomalous B (Ni) vacancy defects, with their formation energies being significantly lower than those of the corresponding B vacancy defects in the other 9 HH compounds. This anomaly can be attributed to the strength of the A-B bonds, where a decrease in bond strength leads to a decrease in the formation energy of B vacancies. This approach of exploring the influence of interatomic bond strength on defect formation is not only insightful for HH compounds but also holds potential applications in defect studies across various materials, offering a broader perspective on the fundamental mechanisms governing defect formation and stability.

中文翻译：

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AIIINiSb (AIII=Sc, Y, Er) half-Heusler 材料中的 A-Ni 化学键引发异常空位缺陷的形成


缺陷通过改变电子能带结构并显着影响其性能，对热电材料产生深远影响。尽管是一种潜在有前途的热电材料，但半赫斯勒（HH）化合物ABX缺陷形成的机制仍不清楚，这阻碍了其热电性能的增强。在本研究中，我们研究了 ANiSb (A = Sc, Y, Er) 和其他 9 种 HH 化合物，即 ANiSn (A = Ti, Zr, Hf)、AFeSb (A = V, Nb, Ta) 的本征缺陷形成能和 ACoSb（A = Ti、Zr、Hf），使用第一原理计算和热力学。结果表明，ANiSb (A = Sc, Y, Er) 表现出反常 B (Ni) 空位缺陷，其形成能明显低于其他 9 种 HH 化合物中相应的 B 空位缺陷。这种异常现象可归因于AB键的强度，其中键强度的降低导致B空位的形成能降低。这种探索原子间键强度对缺陷形成影响的方法不仅对 HH 化合物具有深刻的洞察力，而且在各种材料的缺陷研究中也具有潜在的应用，为控制缺陷形成和稳定性的基本机制提供了更广阔的视角。