First - principles study of the structural , elastic , and electronic properties of the cubic perovskite BaHfO 3

First principles study of structural, elastic, and electronic properties of the cubic perovskitetype BaHfO3 has been performed using the plane wave ultrasoft pseudo-potential method based on density functional theory with revised Perdew-Burke-Ernzerhof exchange-correlation functional of the generalized gradient approximation (GGA-RPBE). The calculated equilibrium lattice constant of this compound is in good agreement with the available experimental and theoretical data reported in the literatures. The independent elastic constants (C 11, C 12, and C 44), bulk modules B and its pressure derivatives B, compressibility β, shear modulus G, Young’s modulus Y, Poisson’s ratio ν, and Lamé constants (μ, λ) are obtained and analyzed in comparison with the available theoretical and experimental data for both the singlecrystalline and polycrystalline BaHfO3. The band structure calculations show that BaHfO3 is a indirect bandgap material (R-Γ = 3.11 eV) derived basically from the occupied O 2p and unoccupied Hf 5d states, and it still awaits experimental confirmation. The density of states (total, site-projected, and l -decomposed) and the bonding charge density calculations make it clear that the covalent bonds exist between the Hf and O atoms and the ionic bonds exist between the Ba atoms and HfO3 ionic groups in BaHfO3. From our calculations, it is shown that BaHfO3 should be promising as a candidate for synthesis and design of superhard materials due to the covalent bonding between the transition metal Hf 5d and O 2p states. PACS numbers: 31.15.A-, 31.15.ae, 87.19.rd Submitted to: J. Phys.: Condens. Matter ‡ Corresponding author.