Effect of different RE site ionic radii on the electronic structures and elastic properties of Ba2RENbO6: A first-principles study

Abstract

RE site ionic radius has a critical influence on the properties of double perovskite oxide Ba2RENbO6. In this paper, the electronic structures and elastic properties of Ba2RENbO6 (RE = Ho, Er, Yb) have been calculated by using the plane-wave pseudopotential density functional theory, and the effect of the different RE site ions on the structures and properties of Ba2RENbO6 is discussed. Results indicate that Ba2RENbO6 (RE = Ho, Er, Yb) are all direct bandgap semiconductors with a bandgap of 0.95 eV, 1.26 eV and 2.36 eV, respectively. With the decrease of the RE site ionic radius of Ba2RENbO6 (RE = Ho, Er, Yb), RE–O and Nb–O covalent bonds are enhanced, and the elastic constants ([Formula: see text], [Formula: see text], [Formula: see text]), elastic modulus ([Formula: see text], [Formula: see text], [Formula: see text]), [Formula: see text], Poisson’s ratio ([Formula: see text]), the Debye temperature [Formula: see text], Gruneisen parameters [Formula: see text] all show a trend of increase. The elastic and thermodynamic properties are all improved with the decreasing radius of RE site ion.