CaAl_(2)X_(2)(X=C,Si,Ge)的稳定性、电子结构和力学性质研究

Study on stabilities,electronic structures and mechanical properties of CaAl_(2)X_(2)(X=C,Si,Ge)

由于AB_(2)X_(2)类型的材料在储能、催化、超导、发光等领域都有着潜在应用价值,因此得到了广泛关注.本文通过第一原理方法计算分析了CaAl_(2)X_(2)(X=C,Si,Ge)的材料声子谱、电子结构、力学性质和硬度,其主要结果为:材料晶格常数的计算结果和实验值都与理论结构符合的很好;CaAl_(2)C_(2)和CaAl_(2)Si 2材料的声子谱中没有出现虚频,表明这两种材料在热力学及动力学上是稳定的;计算的材料的能带结构表明,CaAl_(2)Si 2和CaAl_(2)Ge_(2)具有金属特性,CaAl_(2)C_(2)具有较小带隙的间接半导体材料.这类材料的金属特性,热稳定性及力学各项异性特征对于其作为二次电池活性电极有着重要影响,因此本文的研究结果可为相关领域的研究提供较好的理论依据及参考.

AB_(2)X_(2)have attracted much attention for their potential applications in energy storage,catalysis,superconductivity,luminescence and so on.Based on the first-principles calculations,we investigate phonon dispersions,electronic structures,mechanical properties,and hardnesses of the CaAl_(2)X_(2)(X=C,Si,Ge).The computed equilibrium lattice constants of CaAl_(2)X_(2)(X=C,Si,Ge)are in agreement with the experimental values and previous calculated data.The calculated band structures of CaAl_(2)Si 2 and CaAl_(2)Ge_(2)show that these materials have metallic properties.CaAl_(2)C_(2)is indirect semiconductor with small band gap.The metallic properties,thermal stabilities and mechanical anisotropic characteristics of CaAl_(2)X_(2)(X=C,Si,Ge)have important influence on these materials used as the active electrode of secondary batteries.Therefore,the research results can provide a good theoretical basis and reference for the research in related fields.