Density functional theory calculations were made of bulk cerium oxide doped with magnetic impurities of cobalt atoms in the presence of oxygen vacancies. Using the framework of the DFT+U approach to take into account the effects of electronic correlations in the Ce 4f states, the relative stability of different configurations of vacancies was evaluated. It was shown that,  within the approximations considered, the vacancies tend to locate close to the Co impurities. In addition, the issue of the charge localization that takes place due to de-oxygenation processes was addressed; finding that the excess electrons resided at Ce atoms which were next-nearest neighbors of the vacancy sites.

Charge Localization in Co-Doped Ceria with Oxygen Vacancies. G.E.Murgida, V.Vildosola, V.Ferrari, A.M.Llois: Solid State Communications, 2012, 152[5], 368–71