X-Ray Photoelectron Spectroscopic Study of the Surface Reaction of Uranium–Niobium Alloy with O₂

Abstract

The initial oxidation of uranium–niobium alloy in oxygen atmosphere at 298 K has been studied by X-ray photoelectron spectroscopy (XPS). For comparison, the adsorption of oxygen on pure metal niobium and uranium has also been studied. The changes of U4f, Nb3d and O1s spectra during in situ oxidation indicate that the adsorption of oxygen on uranium–niobium alloy surfaces first leads to the formation of UO 2 and NbO; then NbO 2 and Nb 2 O 5 are detected with increasing exposures of oxygen. The segregations of U and Nb to the uranium–niobium alloy surfaces are observed at different oxidation stages. The oxide film formation of uranium–niobium alloy is faster than that of pure uranium at initial oxidation stages.