Modeling of amorphous phase formation and its thermodynamic behaviour in Ce[sbnd]Mg[sbnd]H, Ce[sbnd]Ni[sbnd]H and Mg[sbnd]Ni[sbnd

Abstract

As a hydrogen storage material, ReMg (Re = Rear Earth metal) alloys hold great promises for sustainable hydrogen energy development. In this work, we aim to explore the reaction route and thermodynamic conditions for Ce/Mg-based alloys with good hydriding property. Using the extended Miedema model, the formation enthalpies of CeH, MgH and NiH single metal hydrides were calculated. Based on the potential of hydrogen and metal, the enthalpy of elastic contribution between metal and hydrogen was considered to yield a more rational estimation of the formation enthalpy. Similar method was adopted to estimate the solid-solution enthalpies and amorphous formation enthalpies of CeMgH, CeNiH and MgNiH hydrides, on which the maximum hydrogen bonding capacities of these three hydrides were induced. These thermodynamic enthalpies of binary and ternary systems obtained in this study exhibit good consistency with the relevant experimental data reported in peer studies. In addition, the effect of varying the concentrations of Ce, Mg and Ni on the enthalpy of hydride formation was simulated. The amorphous forming composition ranges (AFCR) CeMgH, CeNiH and MgNiH hydrides were established and sub-divided into the spontaneous, easy and the hard forming zones. The result of this study may serve as a useful reference for the research and fabrication of the corresponding hydrides.