CeNbO4 a potential electrolyte for solid oxide fuel cells

CeNbO4 is a material of considerable interest for solid oxide fuel cells and other environmentally friendly applications. The low-temperature monoclinic phase of this material tends to be hyperstoichiometric incorporating extra oxygen up to CeNbO4.25. Materials containing cerium are challenging to treat theoretically as strongly correlated materials are not well described by standard density functional theory. Here we study CeNbO4 using the co-called LDA+U approach. We consider different interstitial positions for extra oxygen atoms and study how the formation energies of such defects depend on the degree of the localization of Ce f-states described by parameter U. We propose most likely interstitial sites for extra oxygen to occupy in the CeNbO4 lattice and paths of oxygen migration.