Exploring cluster formation in uranium oxidation using high resolution X-ray spectroscopy at elevated temperatures

Abstract Uranium dioxide (UO2) is a complex material with significant relevance to nuclear energy, materials science, and fundamental research. Understanding its high-temperature behavior is crucial for developing new uranium-based materials and improving nuclear fuel efficiency in nuclear reactors....

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Main Authors: Elena F. Bazarkina, Stephen Bauters, Yves Watier, Stephan Weiss, Sergei M. Butorin, Kristina O. Kvashnina
Format: Article
Language:English
Published: Nature Portfolio 2025-04-01
Series:Communications Materials
Online Access:https://doi.org/10.1038/s43246-025-00795-2
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author Elena F. Bazarkina
Stephen Bauters
Yves Watier
Stephan Weiss
Sergei M. Butorin
Kristina O. Kvashnina
author_facet Elena F. Bazarkina
Stephen Bauters
Yves Watier
Stephan Weiss
Sergei M. Butorin
Kristina O. Kvashnina
author_sort Elena F. Bazarkina
collection DOAJ
description Abstract Uranium dioxide (UO2) is a complex material with significant relevance to nuclear energy, materials science, and fundamental research. Understanding its high-temperature behavior is crucial for developing new uranium-based materials and improving nuclear fuel efficiency in nuclear reactors. Here we study the evolution of uranium state during the oxidation of UO2 in air at temperatures up to 550 °C using the in situ X-ray absorption spectroscopy in high energy resolution fluorescence detection mode at the U M4 edge, combined with electronic structure calculations. Our data reveal a complex sequence of events occurring over minutes and hours at elevated temperatures, including changes in the electronic and local structure, 5 f electron occupancy, the formation of U cuboctahedral clusters, and the creation of U4O9 and U3O7 mixed U oxide phases. These findings highlight the fundamental role of clustering processes and pentavalent uranium in both the oxidation process and the stabilization of uranium materials.
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spelling doaj-art-1bd38698791f4dc2ab8af91beb5a69c32025-08-20T02:28:10ZengNature PortfolioCommunications Materials2662-44432025-04-01611910.1038/s43246-025-00795-2Exploring cluster formation in uranium oxidation using high resolution X-ray spectroscopy at elevated temperaturesElena F. Bazarkina0Stephen Bauters1Yves Watier2Stephan Weiss3Sergei M. Butorin4Kristina O. Kvashnina5Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf (HZDR)Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf (HZDR)ESRF, The European Synchrotron, CS40220Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf (HZDR)Condensed Matter Physics of Energy Materials, X-ray Photon Science, Department of Physics and Astronomy, Uppsala UniversityInstitute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf (HZDR)Abstract Uranium dioxide (UO2) is a complex material with significant relevance to nuclear energy, materials science, and fundamental research. Understanding its high-temperature behavior is crucial for developing new uranium-based materials and improving nuclear fuel efficiency in nuclear reactors. Here we study the evolution of uranium state during the oxidation of UO2 in air at temperatures up to 550 °C using the in situ X-ray absorption spectroscopy in high energy resolution fluorescence detection mode at the U M4 edge, combined with electronic structure calculations. Our data reveal a complex sequence of events occurring over minutes and hours at elevated temperatures, including changes in the electronic and local structure, 5 f electron occupancy, the formation of U cuboctahedral clusters, and the creation of U4O9 and U3O7 mixed U oxide phases. These findings highlight the fundamental role of clustering processes and pentavalent uranium in both the oxidation process and the stabilization of uranium materials.https://doi.org/10.1038/s43246-025-00795-2
spellingShingle Elena F. Bazarkina
Stephen Bauters
Yves Watier
Stephan Weiss
Sergei M. Butorin
Kristina O. Kvashnina
Exploring cluster formation in uranium oxidation using high resolution X-ray spectroscopy at elevated temperatures
Communications Materials
title Exploring cluster formation in uranium oxidation using high resolution X-ray spectroscopy at elevated temperatures
title_full Exploring cluster formation in uranium oxidation using high resolution X-ray spectroscopy at elevated temperatures
title_fullStr Exploring cluster formation in uranium oxidation using high resolution X-ray spectroscopy at elevated temperatures
title_full_unstemmed Exploring cluster formation in uranium oxidation using high resolution X-ray spectroscopy at elevated temperatures
title_short Exploring cluster formation in uranium oxidation using high resolution X-ray spectroscopy at elevated temperatures
title_sort exploring cluster formation in uranium oxidation using high resolution x ray spectroscopy at elevated temperatures
url https://doi.org/10.1038/s43246-025-00795-2
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