Jump to main content
Jump to site search

Issue 28, 2010
Previous Article Next Article

Raman spectroscopic studies of defect structures and phase transition in hyper-stoichiometric UO2+x

Author affiliations

Abstract

A method to determine the defect structures in hyper-stoichiometric UO2+x using a combination of XRD and Raman spectroscopy has been developed. A sequence of phase transitions, from cubic to tetragonal symmetry, occurs with increasing degree of non-stoichiometry. This sequence proceeds from a cubic phase through an intermediate t-type tetragonal (axial ratio c/a = 1) phase to a final t-type tetragonal (c/a ≠ 1) phase. Four distinct structural defect regions can be identified in the stoichiometry range, UO2 to U3O7: (i) a random point defect structure (x (in UO2+x) ≤ 0.05); (ii) a non-stoichiometry region (0.05 ≤ x ≤ 0.15) over which point defects are gradually eliminated and replaced by the Willis 2 : 2 : 2 cluster; (iii) a mixture of Willis and cuboctahedral clusters (0.15 ≤ x ≤ 0.23); (iv) the cuboctahedral cluster (x ≥ 0.23). The geometry and steric arrangement of these defects is primarily determined by the concentration of the excess-oxygen interstitials.

Graphical abstract: Raman spectroscopic studies of defect structures and phase transition in hyper-stoichiometric UO2+x

Back to tab navigation

Supplementary files

Publication details

The article was received on 04 Dec 2009, accepted on 31 Mar 2010 and first published on 08 Jun 2010


Article type: Paper
DOI: 10.1039/B925495A
Citation: Phys. Chem. Chem. Phys., 2010,12, 8109-8118
  •   Request permissions

    Raman spectroscopic studies of defect structures and phase transition in hyper-stoichiometric UO2+x

    H. He and D. Shoesmith, Phys. Chem. Chem. Phys., 2010, 12, 8109
    DOI: 10.1039/B925495A

Search articles by author

Spotlight

Advertisements