REACTIONS OF LITHIUM HYDRIDE AND BERYLLIUM HYDRIDE - THERMAL STUDIES AND IDENTIFICATION OF PRODUCTS

Using simultaneous differential thermal analysis and thermogravimetric analysis, and powder X-ray diffraction, we determined that the reacti ons of lithium hydride and beryllium hydride follow the pathway LiH BeH2 --> 500 K LiBeH3 --> 590 K 1/2Li2BeH4 + 1/2Be + 1/2H2 up for reac tion mixtures containing less than 66.6 mol.% LiH, and 2LiH + BeH2 --> 500 K Li2BeH4 for reaction mixtures containing 66.6 mol.% LiH or more . LiBeH3 undergoes fusion at 430 K Li2BeH4 has two thermal transitions at 550 K and 660 K; the first may be intramolecular rearrangement and the second may be fusion. The two products are indistinguishable by p owder X-ray diffraction.