The modelling of O vacancies in bulk ceria and on the low-index surfaces, as well as O vacancy migration in the bulk, were considered. Density functional theory, corrected for on-site Coulomb interactions, was used since density functional theory was unable to describe correctly the electronic structure of defective ceria. A description of O vacancies was obtained which was consistent with experiment; with localization of charge on the Ce ions neighboring the vacancy site. Confirming classical interatomic potential results, the O vacancy formation energy was reduced on surfaces, as compared with the bulk. An elastic-band approach was applied to the study of vacancy migration in bulk ceria; yielding a diffusion path and energy barrier which were compared with previous studies.

Oxygen Vacancy Formation and Migration in Ceria. M.Nolan, J.E.Fearon, G.W.Watson: Solid State Ionics, 2006, 177[35-36], 3069-74