An X‐ray photoelectron spectroscopic study of a nitric acid/argon ion cleaned uranium metal surface at elevated temperature

Abstract

X-ray photoelectron spectroscopy has been used to study the surface of uranium metal cleaned by nitric acid treatment and argon ion etching, followed by heating in a high vacuum. The surface is shown to contain U02-, species over the entire temperature range studied. Heating to temperatures in the range 400600 O C generates a mixture of this oxide, the metal and a carbide and/or oxycarbide species.~

The Influence of Vacuum Annealing on the Nucleation and Growth Kinetics of Uranium Hydride

“…Analysis of the U4f region for the annealed sample after Ar + ion etching provided evidence to suggest the presence of a duplex oxide structure, consisting of a near stoichiometric dioxide outer layer with an oxy-carbide inter-layer between the dioxide and metal (Figure 3). The evolution of the peak in the U4f 7/2 region at (377.8 eV) and U4f 5/2 region (at 388.4 eV) in addition to the development of an additional peak in the C1s region (Figure 4, 281.8 eV) is similar to the heat induced formation of an oxycarbide (UO x C y ) as reported by Kraiem et al [12], Paul and Sherwood [13] and observed in the heat affected zone of welded uranium by Petherbridge et al [14]. The work of Orlov et al [15] would suggest the UO x C y sub layer was formed by the carbothermic segregation and reaction of bulk carbon impurities (ca 50 ppm) at the oxide metal interface.…”