压强效应下Ba2YNbO6的弹性性质与电子结构的第一性原理计算

First Principles Calculations of Elastic Properties and Electronic Structure of Ba_2YNbO_6 under Pressure

采用基于密度泛函理论的平面波赝势方法,计算了不同压强下立方结构双钙钛矿氧化物Ba2YNb O6的弹性性质与电子结构。计算结果表明:平衡状态下Ba2YNb O6为延展性材料,且延展性随压强的增大而提高;弹性常数,弹性模量和泊松比均随压强的增大近线性增大;Ba2YNb O6为直接带隙半导体,平衡状态下带隙宽度为2.55 e V,且带隙值随压强的增大而减小;费米面附近的能带主要由O 2p,Nb 4d和Y 4d层的电子态密度确定,增大压强使态密度峰有偏离费米面的趋势,并且态密度展宽,峰发生劈裂。

The elastic properties and structure of cubic double perovskite oxide Ba2 YNb O6under different pressures were calculated by the plane-wave pseudopotential density functional theory（ DFT）. The results indicate that： Ba2 YNb O6shows a ductile property at equilibrium state,and the ductility increases with the increase of extern pressures; when the pressure is enhanced,the elastic constants,elastic modulus and Poisson’s ratio all increase; Ba2 YNb O6is a direct band gap semiconductor with a band gap of 2. 55 e V at equilibrium state,and the band gap decreases with the increase of the pressure; The energy band near Fermi level is determined by the density of states of O 2p,Nb 4d and Y 4d electrons,and increasing the pressure makes the peak of density of states move away from the Fermi level with large width and splitting.