Temperature-dependent hydrogenation behaviour and hydrogen storage thermodynamics of Mg 0.9 In 0.1 solid solution alloy.

To clarify the hydrogen storage mechanism of Mg(In) solid solution, the hydrogenation and dehydrogenation characteristics of Mg 0.9 In 0.1 alloy are systematically studied in this work. It is found that the Mg 0.9 In 0.1 solid solution is first hydrogenated to Mg 3 In and MgH 2 under a hydrogen atmosphere. The polymorphism of Mg 3 In leads to different hydrogenation features of the solid solution in various temperature ranges. Consequently, the reversible dehydrogenation reactions have somewhat distinct enthalpy changes due to the different crystal structures of Mg 3 In. When the hydrogenation temperature is not lower than 340 °C, Mg 3 In can be further hydrogenated to (Mg 1- x In x ) 3 In and MgH 2 . The hydrogenation reactions of both β'-Mg 3 In and β-Mg 3 In are also reversible although they have sloping hydrogenation and dehydrogenation plateaus in pressure-composition isotherms. This work provides new insights into the hydrogen storage mechanism of Mg(In) solid solution.