Structure of ternary imide Li2Ca(NH)2 and hydrogen storage mechanisms in amide-hydride system.

The crystal structure of the ternary imide Li 2Ca(NH) 2 has been determined using neutron powder diffraction data on a deuterated sample. The structure consists of infinite layers of edge-shared Ca[NH] 6 octahedra, which are separated by Li cations. The mobile Li (+) ions in such two-dimensional channels defined by Ca[NH] 6 octahedra layers are shown to have a great impact on the hydrogenation properties of the imide. Through detailed structural analysis on the products at various stages of desorption and absorption of the amide-hydride mixture, we proposed a dehydrogenation mechanism involving the mobile small ions in both amide and hydride and a hydrogen storage mechanism for the ternary imide.