Decreasing the hydrogen desorption temperature of LiNH2 through doping:: A first-principles study -: art. no. 181917

We present a theoretical approach to investigate the possibility of reducing desorption temperature of LiNH2 by partial element substitution. The approach was based on a first-principles study of electronic structure of LiNH2 and (Li,Mg)NH2. Results of the LiNH2 study showed that LiNH2 is nonmetallic, the bonding between Li and N is ionic, and the bonding between N and H is strongly covalent. Results of the (Li,Mg)NH2 study showed that the bonding nature of Li-N and N-H is the same as in LiNH2, but the bond strength of N-H was reduced. In addition, the system becomes metal-like after substitution. These two major differences can be used to explain the experimental observation that the hydrogen desorption temperature was reduced by Mg substitution. More important, they might be used as criteria to predict the behavior of other substitution elements. (C) 2005 American Institute of Physics.