钙钛矿结构ZrBeO3稳定性的第一性原理研究

基于密度泛函理论构建了钙钛矿结构ZrBeO3晶体模型,计算了该晶体模型结合能,表明了该构型热力学稳定性;计算出该结构在不同压力下的弹性常数,并据此计算了ZrBeO3的体积模量、剪切模量、杨氏模量、泊松比、BH/GH(体模量/剪切模量)等参数,结果表明该材料具有机械稳定性,随着等静压力增加,材料由脆性向韧性转变;计算了零压下ZrBeO3的硬度,为34.5 GPa,表明该结构晶体应为超硬材料;计算了ZrBeO3的声子能谱,结果表明ZrBeO3在低温零压下热动力学不稳定,为此分析比较了不同压力下的声子能谱、不同原子轨道及化学键布居值,研究表明随着压力增加,Be原子sp杂化后形成的Be-O共价键成分增强、Zr-O键离子键成分增强,晶格动力学趋于稳定。

First-Principles Study on Structural Stability of Perovskite ZrBeO3

Based on density functional theory,a ZrBeO3 crystal model of perovskite structure was constructed.The binding energy of the crystal model was calculated,and the thermodynamic stability of the structure was calculated.The elastic constant of the structure under different pressures was calculated,and ZrBeO3 was calculated according to it.The bulk modulus,shear modulus,Young’s modulus,Poisson’s ratio,BH/GH and other parameters,the calculation results show that the material has mechanical stability,and the material changes from brittle to ductile with increasing isostatic pressure;the hardness of ZrBeO3 under zero pressure is 34.5 GPa,which indicates that the crystal should be superhard material.The calculated phonon energy spectrum show that ZrBeO3 is thermodynamically unstable under low temperature and zero pressure.The phonon spectrum,different atomic orbitals and chemical bond values at different pressures show that the Be-O covalent bond formed by the impurity of Be atom is enhanced and the Zr-O bond ion bond component is enhanced with the increase of pressure.The lattice dynamics tend to be stable.