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

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Mn5Si33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。

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.