Preparation and properties of aluminum hydride

Six crystalline phases of nonsolvated aluminum hydride were prepared by desolvation of AlH/sub 3/ etherate in the presence of small amounts of LiAlH/sub 4/. The most stable phase, ..cap alpha..-AlH/sub 3/, was prepared both from the solid metastable phases and by crystallizing directly from a refluxing diethyl ether-benzene solution. Both the thermal stability and ease of preparation of aluminum hydride phases are highly dependent upon purity.