Hydrostatic pressure effects on the structural, elastic and thermodynamic properties of the complex transition metal hydrides A2OsH6 (A = Mg, Ca, Sr and Ba)

Abstract

ABSTRACTWe report a systematic first-principles density functional theory study on the pressure dependence of the structural parameters, elastic constants and related properties and thermodynamic properties of the complex transition metal hydrides Mg2OsH6, Ca2OsH6, Sr2OsH6 and Ba2OsH6. The calculated structural parameters are in excellent agreement with the existing data in the scientific literature. The single-crystal elastic constants and related properties were predicted using the stress–strain method. The elastic moduli of the polycrystalline aggregates were evaluated via the Voigt–Reuss–Hill approach. The dependences of the lattice parameter, bulk modulus, volume thermal expansion coefficient, isobaric and isochoric heat capacity and Debye temperature on the pressure and temperature, ranging from 0 to 15 GPa and from 0 to 1000 K, respectively, were investigated using the quasi-harmonic Debye model in combination with first-principles calculations.