First-principles study of structural stability and elastic properties of MgPd3 and its hydride

Theoretical study of structural stability and elastic properties of alpha-and beta-MgPd3 intermetallic compounds as well as their hydrides have been carried out based on density functional theory. The results indicate alpha-MgPd3 is more stable than beta phase with increased stability in their hydrides. The calculated elastic constants of alpha-MgPd3 are overall larger than b phase. After hydrogenation, the elastic constants are enlarged. And the elastic moduli exhibit similar tendency. The anisotropy of alpha-MgPd3 is larger than b phase, and the hydrides demonstrate larger anisotropy. Their ductility follows the order of alpha-MgPd3H0.5 < alpha-MgPd3 < beta-MgPd3H < b-MgPd3. Compared with b phase, higher Debye temperature of alpha MgPd3 implies stronger covalent interaction, and the Debye temperature of hydrides increases slightly. The electronic structures demonstrate that the PdePd interaction is stronger than PdeMg, and PdeH bonds play a significant role in the phase stability and elastic properties of hydrides. (C) 2014, National Engineering Research Center for Magnesium Alloys of China, Chongqing University. Production and hosting by Elsevier B.V.