Electrochemical and Surface Characterization of Uranium Dioxide Containing Rare-Earth Oxide (Y_2O_3) and Metal (Pd) Particles

摘要

Four specimens of uranium dioxide doped with rare-earth oxide (Y_2O_3) and/or metal particles (Pd) i.e., UO_2, UO_2-Y_2O_3, UO_2-Y_2O_3-Pd, UO_2-Pd were surface and electrochemically characterized using scanning electron microscopy (SEM/EDX), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry. Surface analyses showed that the dopants are present as a separate phase in the UO_2 matrix and all oxides are non-stoichiometric and contain a large number of defect clusters. Voltammetry shows anodic oxidation begins at sub-thermodynamic potentials and the presence of multiple cathodic reduction peaks indicates the presence of a number of structural domains with different electrochemical reactivities. Corrosion potential (E_(CORR)) and polarization resistance measurements (Rp) in the presence of H_2O_2 suggests that the anodic reactivity of all the specimens is comparable and high compared to 1.5 at% SIMFUEL. The lower Rp values obtained on the doped specimens is consistent with the presence of readily oxidizable cuboctahedral clusters in the oxide matrix.