The changes induced by a surface on atomic diffusion in Li2O were studied using a rigid-ion potential model fitted to ab initio data. The properties of the {111} surface were investigated plane-by-plane at a temperature selected in the superionic phase. The Frenkel defect atomic-fraction and the lithium-ion migration were enhanced mainly in the topmost two planes. An equality of the interstitial and vacancy atomic-fractions, found in the bulk, was not observed in these planes. The surface migration occurred predominantly via two types of nearest-neighbor atomic jumps involving a vacancy mechanism. A geometrical model of the atomic jump-frequency profile permitted an estimation to be made of the reduction in the vacancy migration-energy at the surface. A spontaneous 1 x 2 reconstruction of the {110} surface was also found.

Surface Effects on Atomic Diffusion in a Superionic Conductor: a Molecular Dynamics Study of Lithium Oxide. Hayoun, M., Meyer, M.: Surface Science, 2013, 607, 118-23