Herein, the effects of Cu doping with different concentrations on the stability, elastic properties, and electronic structure of Mg₂Si are investigated by first‐principles calculations based on density functional theory. The research results show that Mg₂Si and Mg_8−xSi_4−yCu_x+y (x, y) = {(0.125, 0), (0, 0.125), (0.25, 0), (0, 0.25), (0.5, 0), (0, 0.5), (1, 0), (0, 1)} are stable in the system. The Cu atoms tend to preoccupy Mg sites in Mg₂Si lattices, and the alloying ability is stronger than that of Mg₈Si_4−yCu_y (y = 0.125, 0.25, 0.5, 1). Although all dopants are brittle phases, the doping behavior of Cu atoms improves the elastic and plastic properties of the Mg₂Si alloy system. The bonding modes of the crystal are also changed. The SiCu covalent bond formed by Mg_8−xSi₄Cu_x (x = 0.125, 0.25, 0.5, 1) further increases the structure stability. Meanwhile, Mg₇Si₄Cu and Mg₈Si₃Cu are changed from semiconducting to metallic state by energy band structure analysis. It not only increases the carrier concentration, but also reduces the free electron transition energy, which improves the conductivity of the intrinsic Mg₂Si. These investigations will provide some theoretical basis for the application of Mg₂Si intermetallic compounds in structural materials and thermoelectric materials.

中文翻译：

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不同浓度Cu掺杂Mg2Si的稳定性，弹性和电子结构研究：第一性原理计算

在此，通过基于密度泛函理论的第一性原理计算，研究了不同浓度的Cu掺杂对Mg ₂ Si的稳定性，弹性和电子结构的影响。研究结果表明，Mg ₂ Si和Mg _{8− x} Si _{4− y} Cu _{x + y}（x，y）= {（0.125，0），（0，0.125），（0.25，0），（0，0.25 ），（0.5、0），（0、0.5），（1、0），（0、1）}在系统中是稳定的。Cu原子倾向于担心Mg ₂ Si晶格中的Mg位，并且合金化能力比Mg ₈ Si _{4- y} Cu强。_y（ y  = 0.125，0.25，0.5，1）。尽管所有掺杂剂均为脆性相，但是Cu原子的掺杂行为改善了Mg ₂ Si合金体系的弹性和塑性。晶体的键合模式也会改变。所述Si 由镁形成的Cu的共价键_{8- X}的Si ₄的Cu _X（ X  = 0.125，0.25mmol，0.5，1）进一步增加结构的稳定性。同时，Mg ₇ Si ₄ Cu和Mg ₈ Si ₃通过能带结构分析，Cu从半导体态变为金属态。它不仅增加了载流子浓度，还降低了自由电子跃迁能，从而提高了本征Mg ₂ Si的电导率。这些研究将为Mg ₂ Si金属间化合物在结构材料和热电材料中的应用提供一些理论依据。