Diffusion in Li2O studied by non-equilibrium molecular dynamics for 873 < T/K < 1603Electronic supplementary information (ESI) available: Movies of diffusion events extracted from NEMD simulations of Li2O. The black dots represent the trace of the Li+ cations throughout the movie. Movie 1: 490 ps trace of one Li+ cation (green) diffusing through the oxide sublattice (red) at 973 K. Here and in Movie 2 the lower part of the movie shows a projection down [010], the upper part is projected down [10

• Main Authors: Mulliner, Alexander D, Aeberhard, Philippe C, Battle, Peter D, David, William I. F, Refson, Keith
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c5cp02628h

The use of non-equilibrium molecular dynamics facilitates the calculation of the cation diffusion constant of Li 2 O at temperatures too low to be accessible by other methods. Excellent agreement with experimental diffusion coefficients has been obtained over the temperature range 873 < T /K < 1603. Diffusion below 1200 K was shown to be dominated by a concerted nearest-neighbour hopping process, whereas in the high-temperature superionic region an additional mechanism involving a six-coordinate interstitial cation site in the anti-fluorite structure becomes increasingly dominant. Our model thus accounts for the transition from the superionic regime to the non-superionic regime. Non-equilibrium molecular dynamics has identified the different diffusion mechanisms that operate in Li 2 O above and below the superionic transition temperature.