Structural studies of Li3N using neutron powder diffraction

The search for alternative fuel has spurred interest in complexes with high hydrogen absorption–desorption capacities. Among these compounds complex metal hydrides have received much attention. More recently, it was proposed that simple metal nitrides such as lithium nitride (Li3N), with its 9 wt% recyclable hydrogen uptake, could be good candidates for reversible hydrogen storage. In this paper, we present the results of detailed structural study of Li3N through the temperature range 20–673 K using neutron powder diffraction. Commercially purchased compound showed a co-existence of alpha and beta phases of Li3N. We observed a steady decline of the beta phase above 473 K and a very small fraction (∼2.5 wt%) remained untransformed at 673 K. This transformation (beta to alpha) was not reversible on cooling.