The structural determination of fluorite-type oxygen excess uranium oxides using EXAFS spectroscopy

Extended x-ray absorption fine structure (EXAFS) spectroscopy has been carried out at 77 K at the uranium LIII edge for UO2, β-U3O7, and U4O9 with the aim of determining the structure of these highly defective (oxygen excess) uranium oxide phases, which are of industrial importance. Use has been mad...

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Bibliographic Details
Published in:The Journal of chemical physics 1986-06, Vol.84 (11), p.6075-6082
Main Authors: JONES, D. J, ROZIERE, J, ALLEN, G. C, TEMPEST, P. A
Format: Article
Language:English
Subjects:
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Exact sciences and technology
Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation
Other interactions of matter with particles and radiation
Physics
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Summary:Extended x-ray absorption fine structure (EXAFS) spectroscopy has been carried out at 77 K at the uranium LIII edge for UO2, β-U3O7, and U4O9 with the aim of determining the structure of these highly defective (oxygen excess) uranium oxide phases, which are of industrial importance. Use has been made of a difference Fourier technique for U3O7, in which the EXAFS of a perfect lattice model is subtracted. U–O bond lengths calculated from the remaining EXAFS signal, assumed to result only from interstitial oxygens, have been used to determine the atomic coordinates of these interstitials. The analysis of EXAFS data in terms of coordination number has allowed an insight into the defect aggregate arrangement of oxygens in U3O7 and U4O9. Furthermore, EXAFS data indicate that the uranium sublattice is perturbed by the incorporation of additional oxygen atoms.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.450795