AVS 63rd International Symposium & Exhibition
    Actinides and Rare Earths Focus Topic Wednesday Sessions
       Session AC+MI-WeA

Paper AC+MI-WeA12
XPS and SIMS Study of the Surface and Interface of Aged C+Implanted Uranium

Wednesday, November 9, 2016, 6:00 pm, Room 103C

Session: Actinide and Rare Earth Theory (2:20-3:40 pm)/Nuclear Power, Waste Remediation and Applications (4:20-6:20 pm)
Presenter: Art Nelson, Lawrence Livermore National Laboratory
Authors: A.J. Nelson, Lawrence Livermore National Laboratory
S. Donald, Lawrence Livermore National Laboratory
J. Siekhaus, Lawrence Livermore National Laboratory
Correspondent: Click to Email
Core-level photoelectron spectroscopy in combination with X-ray excited Auger peak energies were blended with secondary ion mass spectrometry depth profiling to investigate the surface and interfacial chemistry of oxidized C+ ion implanted polycrystalline uranium exposed to air for over 10 years at ambient temperature. Implantation of 33 keV C+ ions into U238 with a dose of 4.3 x 1017 cm-3 produced a physically and chemically modified surface layer that was characterized and shown to initially prevent air oxidation and corrosion of the uranium. The evolution of the previously characterized surface and interfacial layers were now examined by using a combination of the C KLL and U NOV Auger peak energies with the associated chemical shift of the C 1s and U 4f photoelectron lines that defines the Auger parameter resulting in a reliable method for conclusively determining oxidation states independent of binding energy calibration. Results showed definitive Auger line-shapes and were used to produce a chemical state (Wagner) plot for select surface oxide and interfacial carbide. In addition, valence band spectra were used to explore the electronic structure of the aged carbide surface and interface layer. Furthermore, the time-of-flight secondary ion mass spectrometry depth profiling results for the aged sample confirmed an oxidized UC layer over the carbide layer/U metal interface.

The work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.