ABSTRACTWe present a first principles thermodynamic study of O ad-atom and vacancy formation on the AO- and BO2-terminated (001) surfaces of the PbTiO3 (PTO) and LaMnO3 (LMO) cubic perovskites. Our results show that, owing to the highly energetically unfavorable nature of O vacancy formation on these surfaces, O vacancies appear only at high temperatures and practically irrelevant low pressures on the (T, p) surface phase diagram. In contrast, effortless formation of O ad-atoms on the surfaces is encountered at practically achievable pressures and temperatures. Above room temperature and close to atmospheric pressures, we predict clean PbO and TiO2-terminated (001) PTO surfaces as the stable surface phases while partially or fully O ad-atom covered surfaces are found to be more stable for LMO. These results are consistent with the observation that LMO is far more active towards oxidation catalysis than PTO.
Electronic structure and vacancy formation of Li3N
