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2 PublicationsPeculiar thermal behavior of UO2 local structure
Prieur, D.; Epifano, E.; Dardenne, K.; Rothe, J.; Hennig, C.; Scheinost, A.; Neuville, D.; Martin, P.
Abstract
Most materials expand in one, two or all three dimensions with temperature because of the anharmonicity of lattice vibration, and only few behave in the opposite way, i.e. shrink with increasing temperature1. Uranium dioxide, whose thermal properties are of significant importance for the safe use of the nuclear energy2, was considered for a long time to belong to the first group from room temperature to the melting point at 3147 ± 20 K3,4,5. This view was challenged by recent in situ synchrotron X-ray diffraction measurements, showing an unusual thermal decrease of the U-O distances up to the melting point6. This thermal shrinkage was interpreted as a consequence of the splitting of the U-O distances due to a change in the U local symmetry from Fm-3m to Pa-37. In contrast to these previous investigations and using an element-specific synchrotron-based spectroscopic method, we show here that the U sublattice remains locally of the fluorite type from 50 K to 1265 K, and that the decrease of the first U-O bond lengths with increasing temperature is associated to an increase of the disorder, which we modelled using the Einstein model. These findings are of significant importance in order to predict the thermal behaviour of nuclear fuel, as well as to understand the accumulation of fission product in the nuclear fuel.
Involved research facilities
- Rossendorf Beamline at ESRF DOI: 10.1107/S1600577520014265
Related publications
- DOI: 10.1107/S1600577520014265 is cited by this (Id 27658) publication
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Inorganic Chemistry 57(2018)23, 14890-14894
DOI: 10.1021/acs.inorgchem.8b02657
Cited 5 times in Scopus -
Lecture (Conference)
ATAS 2018 - 4th International Workshop on Advanced Techniques in Actinide Spectroscopy, 06.-09.11.2018, Nice, France
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- Final Draft PDF 184 kB Secondary publication
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