Oxidation Driven Decomposition of CeNbO4 in Pure Oxygen

CeNbO4 possesses oxygen hyper-stoichiometry at ambient and moderate temperature. At elevated temperature CeNbO4+delta is thermally reduced to near stoichiometric CeNbO4 accompanied by a structural phase transition. Above the phase transition temperature reoxidation of the material occurred in a pure oxygen atmosphere, and in situ X-ray diffraction revealed that CeNbO4 decomposed to CeO2 and CeNb3O9. Upon further heating CeNbO4 reappeared by a solid state reaction between CeO2 and CeNb3O9. The present findings demonstrate that CeNbO4+delta is metastable with respect to CeO2 and CeNb3O9 at low temperature.