XPS study of the surface chemistry of UO2 (111) single crystal film

Konstantin I. Maslakov, Yury A. Teterin, Aleksej J. Popel*, Anton Yu Teterin, Kirill E. Ivanov, Stepan N. Kalmykov, Vladimir G. Petrov, Ross Springell, Thomas B. Scott, Ian Farnan

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

15 Citations (Scopus)
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Abstract

A (111) air-exposed surface of UO2 thin film (150 nm) on (111) YSZ (yttria-stabilized zirconia) before and after the Ar+ etching and subsequent in situ annealing in the spectrometer analytic chamber was studied by XPS technique. The U 5f, U 4f and O 1s electron peak intensities were employed for determining the oxygen coefficient kO = 2 + x of a UO2+x oxide on the surface. It was found that initial surface (several nm) had kO = 2.20. A 20 s Ar+ etching led to formation of oxide UO2.12, whose composition does not depend significantly on the etching time (up to 180 s). Ar+ etching and subsequent annealing at temperatures 100–380 °C in vacuum was established to result in formation of stable well-organized structure UO2.12 reflected in the U 4f XPS spectra as high intensity (∼28% of the basic peak) shake-up satellites 6.9 eV away from the basic peaks, and virtually did not change the oxygen coefficient of the sample surface. This agrees with the suggestion that a stable (self-assembling) phase with the oxygen coefficient kO ≈ 2.12 forms on the UO2 surface.

Original languageEnglish
Pages (from-to)582-588
Number of pages7
JournalApplied Surface Science
Volume433
DOIs
Publication statusPublished - 1 Mar 2018

Keywords

  • Ar sputtering
  • Ionic composition
  • Surface chemistry
  • Thin film
  • UO
  • XPS

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