Characterization and stability of thin oxide films on plutonium surfaces

• Published in: Surface science Vol. 605; no. 3; pp. 314 - 320
• Main Authors: Flores, H.G. García, Roussel, P., Moore, D.P., Pugmire, D.L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.02.2011; Elsevier
• Subjects: AES; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Metal oxides; Metal surfaces; Oxidation; Oxide coatings; Oxides; Physics; Plutonium; Plutonium dioxide; Stability; X-ray photoelectron spectroscopy; X-rays; XPS; XPS; Oxidation; Plutonium; AES; Thin films; Actinides
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2010.10.034

X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were employed to study oxide films on plutonium metal surfaces. Measurements of the relative concentrations of oxygen and plutonium, as well as the resulting oxidation states of the plutonium (Pu) species in the near-surface region are presented. The oxide product of the auto-reduction (AR) of plutonium dioxide films is evaluated and found to be an oxide species which is reduced further than what is expected. The results of this study show a much greater than anticipated extent of auto-reduction and challenge the commonly held notion of the stoichiometric stability of Pu 2O 3 thin-films. The data indicates that a sub-stoichiometric plutonium oxide (Pu 2O 3 − y ) exists at the metal–oxide interface. The level of sub-stoichiometry is shown to depend, in part, on the carbidic contamination of the metal surface. ► The O/Pu thin-film system has been studied and shown to be very complex. ► Pu 2O 3 exists as a sub-stoichiometric species and is better described as Pu 2O 3-y. ► Range of observed stoichiometries: O/Pu = 1.15 - 1.5 (Pu 2O 3-y, y = 0 - 0.7). ► Level of sub-stoichiometry depends greatly on carbide contamination.