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: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2025-04-01
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| Series: | Communications Materials |
| Online Access: | https://doi.org/10.1038/s43246-025-00795-2 |
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| Summary: | 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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| ISSN: | 2662-4443 |