Surface characterisation of α-, β-, γ-, and δ-UO3 using X-ray photoelectron spectroscopy

Abstract

X-Ray photoelectron spectroscopy, i.r. spectroscopy, and X-ray diffraction have been used to characterise the higher oxides α-, β-, γ-, and δ-UO₃. While the i.r. and X-ray diffraction results may be used to characterise each oxide, the X-ray photoelectron spectra for the four phases are very similar. During reduction of the oxide surface in the spectrometer, changes in the spectra were observed which were shown to be associated with particular oxidation states of the metal rather than different uranium atom co-ordination sites within the oxide. A close structural relationship is demonstrated between these oxides and the product at the surface of air-oxidised UO₂ fuel.