The high-temperature superionic phase of lithium oxide was characterized by a high concentration of Frenkel defects and a diffusion mechanism involving several types of atomic jumps. The tracer-correlation factor was calculated and the migration paths of the Li ions obtained by molecular dynamics were analyzed. A kinetic Monte Carlo code, simulating the lithium vacancy diffusion, was developed and used to predict the correlation factor as a function of the atomic fraction of defects. There was a good agreement with the result directly obtained by molecular dynamics. Analysis of the jump paths showed that direct exchange between a vacancy and a migrating atom was the main feature of the diffusion mechanism. The other atomic jumps, although complex, mostly involved vacancies. The Li+ fast-diffusion proceeded via a vacancy mechanism involving several jump types.

Migration and Correlation in Highly Defective Systems: Fast-Diffusion in Lithium Oxide. Hayoun, M., Meyer, M.: Acta Materialia, 2008, 56[6], 1366-73