First principles calculations of elastic properties and electronic structure of Ba₂YNbO₆ under pressure

The elastic properties and structure of cubic double perovskite oxide Ba₂YNbO₆ under different pressures were calculated by the plane-wave pseudopotential density functional theory (DFT). The results indicate that: Ba₂YNbO₆ shows 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; Ba₂YNbO₆ is a direct band gap semiconductor with a band gap of 2.55 eV 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.