Kinetics and mechanism of surface plutonium oxycarbide formation

Initial studies of plutonium oxycarbide surface films on metal have been reported to slow the rate of metal corrosion in dry conditions. Exploiting this property presents a unique opportunity in the safe storage of this radioactive and toxic material; however, more fundamental work is required. The plutonium, carbon, and oxygen ratio of these surface films is investigated here using x-ray photoelectron spectroscopy (XPS) and is shown to be nonstoichiometric. The origin of the carbon in the formation of surface plutonium oxycarbide films is probed using a combination of XPS, x-ray diffraction, and secondary ion mass spectrometry and is shown to occur from the metal interstitial impurity. The kinetics of plutonium oxycarbide film growth for a specific bulk carbon concentration have been determined.