The effects of various alloying elements on the performance of Mg-Mg₂Ni hydrogen storage alloys were investigated by performing first-principles density functional theory calculations. We examined the important characteristics of hydrogen storage alloys by considering both Mg-based solid solution and Mg₂Ni-based intermetallic compound phases, where the hydride forms are MgH₂ and Mg₂NiH₄, respectively. In particular, qualitatively valid information for predicting changes in plateau pressures in the pressure-composition-temperature (PCT) curve was provided by calculating changes in the energy of related hydrogenation reactions. The effects of alloying elements on volume changes due to hydrogenation reactions were also obtained to provide additional criteria for the practical use of hydrogen storage alloys. For the Mg₂Ni-based intermetallic compound, we examined the site preference of each alloying element, considering the designated stoichiometry of the base alloy. Based on the revealed site preferences, the effects of various possible alloying elements on the properties of Mg₂Ni-based hydrides were also examined. Electronic structure analyses were further conducted to elucidate the detailed mechanisms underlying the role of the additional solute elements.

中文翻译：

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溶质元素在 Mg-Mg2Ni 储氢合金中的作用：第一性原理计算研究


通过第一性原理密度泛函理论计算，研究了各种合金元素对 Mg-Mg₂Ni 储氢合金性能的影响。我们通过考虑 Mg 基固溶体和 Mg₂Ni 基金属间化合物相来研究储氢合金的重要特性，其中氢化物形式分别为 MgH₂ 和 Mg₂NiH₄。特别是，通过计算相关氢化反应的能量变化，提供了预测压力-成分-温度 （PCT） 曲线中平台压力变化的定性有效信息。还获得了合金元素对加氢反应引起的体积变化的影响，为储氢合金的实际应用提供了额外的标准。对于 Mg₂Ni 基金属间化合物，我们考虑了基础合金的指定化学计量，检查了每种合金元素的位点偏好。根据揭示的位点偏好，还研究了各种可能的合金元素对 Mg₂Ni 基氢化物性能的影响。进一步进行了电子结构分析，以阐明其他溶质元素作用的详细机制。