PNNL

Abstract

Density functional theory is used to determine the stabilization mechanisms of LaFeO3 (010) surfaces over a range of surface oxygen stoichiometries. For the stoichiometric LaO surface, and for reduced surface terminations, charge redistribution is needed for stabilization that results in an electron-rich surface. In contrast, in the case of the stoichiometric FeO2 surface and oxidized surface terminations with low-coordinated oxygen atoms, a hole-rich surface is needed for stabilization. The calculations further predict that low coordinated oxygen atoms are more stable on LaO-type surface terminations than on FeO2-type surface terminations due to relatively strong electron transfer. In addition to these electronic effects, atomic relaxation is found to be an important contributor to charge compensation, with LaO-type surface terminations exhibiting larger atomic relaxations than FeO2-type surface terminations. As a result, there is a significant contribution from the sub-layers to charge compensation in LaO-type surface terminations.