Uranium passivation by C implantation: A photoemission and secondary ion mass spectrometry study |
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Authors: | AJ Nelson TE Felter KJ Wu C Evans JL Ferreira WJ Siekhaus W McLean |
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Institution: | Lawrence Livermore National Laboratory, Livermore, CA 94550, United States |
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Abstract: | Implantation of 33 keV C+ ions into polycrystalline U238 with a dose of 4.3 × 1017 cm−2 produces a physically and chemically modified surface layer that prevents further air oxidation and corrosion. X-ray photoelectron spectroscopy and secondary ion mass spectrometry were used to investigate the surface chemistry and electronic structure of this C+ ion implanted polycrystalline uranium and a non-implanted region of the sample, both regions exposed to air for more than a year. In addition, scanning electron microscopy was used to examine and compare the surface morphology of the two regions. The U 4f, O 1s and C 1s core-level and valence band spectra clearly indicate carbide formation in the modified surface layer. The time-of-flight secondary ion mass spectrometry depth profiling results reveal an oxy-carbide surface layer over an approximately 200 nm thick UC layer with little or no residual oxidation at the carbide layer/U metal transitional interface. |
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Keywords: | X-ray photoelectron spectroscopy (XPS) Time-of-flight secondary ion mass spectrometry (ToF-SIMS) Uranium Uranium carbide Ion implantation |
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