Paper Details

This paper focuses primarily on the study of the structural, electronic and dehydrogenation properties of thesix considered polymorphs of magnesium hydride (α - rutile TiO2, P42/mnm, β - cubic modified CaF2, Pa , γ - orthorhombicPbO2, Pbcn, δ' -orthorhombic, Pbca, ε - orthorhombic, Pnma and cubic - Fm m).The aim of this study is to find out thepolymorph with the most potential for hydrogen storage. For this the total energy calculations are performed in the framework of the density functional theory using the generalized gradient approximation (GGA-PBE).Furthermore, the energyband structure, the density of states (DOS), bulk modulus , bulk modulus derivative and the dehydrogenation properties arecalculated for all the six possible structures. It has been found that the dehydrogenation enthalpy (ΔH) is lower for cubicMgH2(-47.02kJ/mol.H2) which is 18.14% lower than the α -MgH2 having the highest ΔH value(-57.63kJ/mol.H2) causinggreater destabilization, resulting in larger reduction of its dehydrogenation temperature. It is also seen that cubic-MgH2 withthe hydrogen removal energy of ΔE = 0.48eV which differ only by 0.01eVof that of ε-MgH2 which has a lower value of ΔE =0.47eV shows improved dehydrogenation kinetics for enhancing its hydrogen storage properties.

R.SHRIVALLI, V.VASU, “STRUCTURAL, ELECTRONIC AND DEHYDROGENATION PROPERTIES OF THE MAGNESIUM HYDRIDE-A DFT STUDY”, International Journal of Advance Engineering and Research Development (IJAERD), Vol. 6, Issue 8, pp. 130-139, August 2019.