Skip to Main content Skip to Navigation
Journal articles

In-situ high resolution photoelectron spectroscopy study on interaction of sodium with UO2+x film (0 ≤ x ≤ 1)

Abstract : We studied in-situ the interaction of sodium metal with UO2+x (0 ≤ x ≤ 1) using thin films prepared by sputter deposition on Au substrate. X-ray Photoelectron Spectroscopy (XPS) and Grazing Incidence XRay Diffraction (GIXRD) characterized films before and after interaction. The results show that sodium does not reduce stoichiometric UO2 at room temperature. Plasmon loss peaks, observed at the Na1s photoemission (PE) line, are characteristic of metallic sodium particles, and point to a weak interaction between sodium and UO2. The oxidation of the sodium at room temperature takes place only on hyperstoichiometric uranium dioxide films. Indeed, sodium deposition on UO2+x (0 < x ≤ 1), eventually results in the complete reduction of U(VI) down to U(IV). Molecular and atomic oxygen affect differently the oxidation of uranium and sodium. The wetting of the gold by the sodium is much more important when sodium is oxidised by atomic oxygen. This leads to a shift of the Na1s core level peak, while molecular oxygen gives a peak broadening without shift. Atomic oxygen seems to play the same role as the interstitial oxygen present in the UO2+x film. The oxygen dissociation may be the limiting step of sodium oxidation on gold and on UO2. Heat treatment of sodium on UO3 at about 773 K leads to the formation of the NaUO3 film as demonstrated by a quantitative analysis by XPS and GIXRD. The results show also that once U(V) is formed, it stays stable up to at least 973 K, the temperature at which shrinkage of the film is observed.
Document type :
Journal articles
Complete list of metadata

https://hal-emse.ccsd.cnrs.fr/emse-03169835
Contributor : Fatima Lillouch <>
Submitted on : Monday, March 15, 2021 - 5:06:02 PM
Last modification on : Wednesday, March 17, 2021 - 3:07:13 AM

File

 Restricted access
To satisfy the distribution rights of the publisher, the document is embargoed until : 2021-09-15

Please log in to resquest access to the document

Identifiers

Collections

Citation

Concettina Andrello, T. Gouder, Loïc Favergeon, Lionel Desgranges, E. Tereshina-Chitrova, et al.. In-situ high resolution photoelectron spectroscopy study on interaction of sodium with UO2+x film (0 ≤ x ≤ 1). Journal of Nuclear Materials, Elsevier, 2021, 545, pp.152646. ⟨10.1016/j.jnucmat.2020.152646⟩. ⟨emse-03169835⟩

Share

Metrics

Record views

70