A molecular dynamics simulation study of the superionic conductor lithium nitride. I

The authors have performed a molecular dynamics simulation of the superionic conductor Li 3 N at 300K and 400K in order to characterise its structure and transport mechanisms. The distinct Li(1) and Li(2) sublattices are observed experimentally to give complicated temperature-dependent anisotropic mobilities. These have been completely reproduced by the simulation at a qualitative level, although simulated transport coefficients are too high. The defect structure is found to consist of low levels of Frenkel disorder on the Li(2) sublattice and at the higher temperature interstitials are identified in the interplanar region. In accord with observation, Li(2) ions are found to have a remarkable degree of site-localisation.