title: What Is the Actual Local Crystalline Structure of Uranium Dioxide, UO2? A New Perspective for the Most Used Nuclear Fuel.
abstract: Up to now, uranium dioxide, the most used nuclear fuel, was said to have a Fm3̅m crystalline structure from 30 to 3000 K, and its behavior was modeled under this assumption. However, recently X-ray diffraction experiments provided atomic pair-distribution functions of UO2, in which UO distance was shorter than the expected value for the Fm3̅m space group. Here we show neutron diffraction results that confirm this shorter UO bond, and we also modeled the corresponding pair-distribution function showing that UO2has a local Pa3̅ symmetry. The existence of a local lower symmetry in UO2could explain some unexpected properties of UO2that would justify UO2modeling to be reassessed. It also deserves more study from an academic point of view because of its good thermoelectric properties that may originate from its particular crystalline structure.
authors.affiliation: CEA, DEN, DEC F-13108 Saint Paul lez Durance Cedex, France.
authors.forename: L
authors.identifier: http://orcid.org/0000-0002-6327-3482
authors.initials: L
authors.lastname: Desgranges
authors.affiliation: CEA, DEN, DEC F-13108 Saint Paul lez Durance Cedex, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Ma
authors.affiliation: CEA, DEN, DEC F-13108 Saint Paul lez Durance Cedex, France.
authors.forename: Ph
authors.initials: P
authors.lastname: Garcia
authors.affiliation: SPMS, LRC Carmen, CNRS Centrale Supélec , 92295 Châtenay-Malabry, France.|CEA, DEN, DMN F-91191 Gif-sur-Yvette Cedex, France.
authors.forename: G
authors.initials: G
authors.lastname: Baldinozzi
authors.affiliation: SPMS, LRC Carmen, CNRS Centrale Supélec , 92295 Châtenay-Malabry, France.|CEA, DEN, DMN F-91191 Gif-sur-Yvette Cedex, France.
authors.forename: D
authors.initials: D
authors.lastname: Siméone
authors.affiliation: Institut Laue-Langevin , 6 rue Jules Horowitz, B.P. 156, 38042 Grenoble Cedex, France.
authors.forename: H E
authors.initials: HE
authors.lastname: Fischer