Relative impact of H 2 O and O 2 in the oxidation of UO 2 powders from 50 to 300 °C

Abstract The reaction of water and molecular oxygen with stoichiometric uranium dioxide (i.e. UO 2 ) powder at elevated temperature was studied by high-resolution x-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, powder x-ray diffraction (XRD), and scanning electron microscopy (SEM). Oxidation resulting from the dissociative chemisorption of the adsorbing molecules and subsequent incorporation into the oxide lattice was observed and quantified. Molecular oxygen was found to be a stronger oxidation agent than water at elevated temperatures but not at ambient.