Elastic properties of perovskite-type hydride NaMgH3 for hydrogen storage

Mechanical properties of NaMgH3 were investigated using the norm-conserving pseudopotentials and plane waves (PP–PW) within the general gradient approximation (GGA) in the frame of density functional theory (DFT). The elastic constants of NaMgH3 were calculated for the first time. The NaMgH3 compound is found to be mechanically stable at ambient pressure. The linear bulk modulus and the bulk modulus along crystallographic axes of single crystals have been derived using elastic constants. The calculated linear bulk moduli are found to be in good agreement with the theoretical value reported in the literature. Shear and Youngʹs moduli as well as Poissonʹs ratio for ideal polycrystalline NaMgH3 are also calculated. According to the obtained results, NaMgH3 can be classified as brittle material. The shear anisotropic factors and the elastic anisotropy are also discussed. A Debye temperature of 648 K was also determined using theoretical elastic constants.