Ca5Zn3相稳定性和物理性质的第一性原理研究

Phase Stability and Physical Properties of Ca5Zn3 Compound by Using First-principles

关键词:  第一性原理  相稳定性  力学性质  热物理性质  钙锌化合物

Key words:  first principles  phase stability  mechanical properties  thermo-physical properties  compounds of calcium and zinc

摘要:

利用基于密度泛函理论的第一性原理方法对Ca₅Zn₃化合物的晶格常数、形成焓、弹性常数、以及电子态密度等进行计算研究。为了获得Ca₅Zn₃化合物的结构稳定性，考虑了Cr₅B₃、W₅Si₃以及Mn₅Si₃ 3种结构类型，计算得到的形成焓表明：具有Cr₅B₃结构类型的Ca₅Zn₃最稳定，其次为Mn₅Si₃型，最后是W₅Si₃型。对该化合物的弹性常数、电子态密度和电荷密度差进行了计算。最后利用德拜模型，对Ca₅Zn₃的热物理性能进行了计算，获得体积、体积模量、热膨胀系数以及等容热容随温度和压强变化的规律，为该化合物在热电方面的应用提供了理论依据。

Abstract:

Using the first-principles method based on density functional theory, the lattice constants, formation enthalpy, elastic constants, and electronic state densities of Ca₅Zn₃ compounds were calculated and studied. In order to obtain the structural stability of Ca₅Zn₃ compounds, three structural types of Cr₅B₃,W₅Si₃ and Mn₅Si₃ were considered. The calculated formation enthalpies indicate that Ca₅Zn₃ with Cr₅B₃ structure type is the most stable, followed by Mn₅Si₃ type, and finally is W₅Si₃ type. The elastic constants, electronic state densities and charge density difference of Ca₅Zn₃ compound were calculated. Finally, using the Debye model, the thermo-physical properties of Ca₅Zn₃ were calculated, and the laws of volume, bulk modulus, thermal expansion coefficient and isochoric heat capacity with temperature and pressure were obtained. It provides a theoretical basis for the application of this compound in thermoelectric field.