Oxidation of a depleted uranium-5 wt% molybdenum (U-5Mo) alloy in UHV by AES and XPS |
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| Authors: | Simon R. Bacon Martin Brierley Mark A. Baker John F. Watts |
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| Affiliation: | 1. Department of Mechanical Engineering Sciences, University of Surrey, Surrey, GU2 7XH, UK;2. Materials and Analytical Science, Atomic Weapons Establishment, Aldermaston, Reading, RG7 4PR, UK |
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| Abstract: | Early stage oxidation of a dilute-depleted uranium-molybdenum alloy was analysed in situ under ultra-high vacuum conditions by AES and XPS. At the equivalent of less than 300 ns at 1-atm O2, U-5Mo oxidizes to form stoichiometric UO2. No molybdenum oxidation is observed. After an oxygen dose of approximately 39 L, the oxide layer approached a limiting thickness of approximately 2.4 nm. The oxidation kinetics followed a logarithmic rate law, with the best fit to the experimental data for the oxide thickness, d, being given by d = 1.26 log(0.12t + 0.56). Changes in oxygen KLL and 1s peak positions associated with transformation from chemisorbed oxygen to metal oxide were observed at similar oxygen doses of 2.3 and 2.6 L O2 by AES and XPS, respectively, which opens up the possibility of using well-characterized XPS chemical information to inform Auger peak shifts. |
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| Keywords: | AES corrosion molybdenum oxidation uranium XPS |
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