Effect of vacuum heat treatment on plutonium oxide surfaces as studied by XPS and AES

The effect of heating (150 to 5000C) in vacuum a plutonium substrate with a plutonium oxide surface film was studied utilizing X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). When plutonium metal with a surface oxide film is vacuum heat treated, the oxide is reduced by reaction of the substrate metal with the oxide. The reactions occurring were examined by monitoring the binding energies of the Pu(4f/sub 7/2/), O(1s), and C(1s) XPS peaks and observing the C(KLL) Auger electron peak structure. These results were compared with the x-ray diffraction data of Terada et al. (J. Nucl. Mater. 30: 340(1969). The XPS and AES data show that at higher reaction temperatures (400 to 5000C) the surface compound formed is not PuO as indicated by Terada et al., but is instead a plutonium oxycarbide (Pu[C,O]) compound. The Pu(4f/sub 7/2/) binding energies for PuO2, PuO152 (α-Pu2O3), Pu(C,O), and Pu metal are 426.1, 424.4, 423.6, and 422.2 eV, respectively