A study was made of the oxide, in its normal and superionic phase, using lattice dynamic and molecular dynamic calculations. Molecular dynamics simulations were used to study the fast-ion phase and the diffusion behavior of Li and O ions. The results obtained for the diffusion constant and the thermal amplitude of Li were in very good agreement with experimental observations. The pair correlation functions, Li-O-Li bond-angle distribution and views of the positions of Li atoms over a range of time steps, provided a microscopic picture of the local structure. This indicated that, as in other fluorites, the Li ions diffused via an interstitial mechanism but the distortions due to this movement were small. Lattice dynamic calculations were performed using a shell model in the quasi-harmonic approximation. The equilibrium structure, phonon frequencies, elastic constants and specific heat were calculated, and were in excellent agreement with available experimental data.

Superionic Behavior of Lithium Oxide Li2O – a Lattice Dynamics and Molecular Dynamics Study. P.Goel, N.Choudhury, S.L.Chaplot: Physical Review B, 2004, 70[17], 174307 (8pp)