Aluminum Hydride Polymorphs: Preparation, Characterization and Thermal Properties

Two aluminum hydride polymorphs (alpha-AlH3 and beta-AlH3) were prepared by desolvation of AlH3-etherate based on the organometallic synthesis method and the thermal properties of them were investigated using TG-DSC and ex situ XRD under heating and isothermal processes. The results suggest that the alpha polymorph is more stable than the beta polymorph, and the decomposition of the less stable polymorph, beta-AlH3, occurs by an exothermic transformation to the alpha phase followed by the decomposition of alpha-AlH3 into Al and H-2, with partial direct decomposition occurring in the process of phase transition at low temperatures (<100 degrees C).