Be成分对Be_xZn_(1-x)O合金晶体结构、弹性和电子性质的影响

Be-composition effect on structure,elastic and electronic properties of Be_xZn_(1-x)O alloys

基于密度泛函理论的第一性原理计算方法,深入研究了Be成分对Be_xZn_(1-x)O合金(x=0.0,0.125,0.25,0.5,0.75,0.875,1.0)的晶体结构、弹性常数、弹性模量、各向异性以及泊松比的影响.计算得到的结构参数和弹性性质与现有的理论和实验结果一致.研究发现随着Be成分的增加,体弹模量、剪切模量和杨氏模量逐渐增大,而各向异性以及泊松比则缓慢减小.与BeO相比,ZnO展现了较低的各向异性,而且Be_xZn_(1-x)O合金的各向异性度随着Be成分的增加而增加.在0≤x≤1的范围内,Be_xZn_(1-x)O合金具有直接带隙特征,且带隙的弯曲参数b缓慢增加.

First principles calculation of the structure and elastic properties of Bex Zn1-x O alloys have been carried out based on the density-functional theory for the compositions x=0.0, 0. 125, 0.25, 0.5, 0.75, 0.875, 1.0. The effect of Be composition on lattice parameters, elastic constants, bulk modulus, shear modulus, Young modulus, shear anisotropy factor and Poisson ratio was investigated in detail for BexZn1-xO alloys. The calculated structural parameters and elastic properties of BexZn1-x O alloys are in good agreement with the available theoretical and experimental values. It is found that,with increasing Be concentration, the bulk modulus, shear modulus and Young modulus increase monotonously, while shear anisotropy factor and Poisson ratio decrease slowly. The ZnO exhibits low elastic anisotropy compared with BeO, and the degree of the anisotropy increases for Bex Zn1-x O alloys in the 0≤x≤1 composition range. BexZn1-xO alloys have the direct band gap character and the bowing parameter b increases slowly with increasing x.