An Atomic-Scale Understanding of UO2 Surface Evolution During Anoxic Dissolution

Popel, Aleksej J. and Spurgeon, Steven R. and Matthews, Bethany and Olszta, Matthew J and Tan, Beng Thye and Gouder, Thomas and Eloirdi, Rachel and Buck, Edgar C and Farnan, Ian (2020) An Atomic-Scale Understanding of UO2 Surface Evolution During Anoxic Dissolution. ACS Applied Materials & Interfaces. ISSN 1944-8244 DOI

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Our present understanding of surface dissolution of nuclear fuels such as uranium dioxide (UO2) is limited by the use of non-local characterization techniques. Here we discuss the use of state-of-the-art scanning transmission electron microscopy (STEM) to reveal atomic–scale changes occurring to a UO2 thin film subjected to anoxic dissolution in deionised water. No amorphisation of the UO2 film surface during dissolution is observed, and dissolution occurs preferentially at surface reactive sites that present as surface pits which increase in size as the dissolution proceeds. Using a combination of STEM imaging modes, energy-dispersive X-ray spectroscopy (STEM-EDS), and electron energy loss spectroscopy (STEM-EELS), we investigate structural defects and oxygen passivation of the surface that originates from the filling of the octahedral interstitial site in the centre of the unit cells and its associated lattice contraction. Taken together, our results reveal complex pathways for both the dissolution and infiltration of solutions into UO2 surfaces.

Item Type: Article
Uncontrolled Keywords: 2020AREP; IA76
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
08 - Green Open Access
Journal or Publication Title: ACS Applied Materials & Interfaces
Identification Number:
Depositing User: Sarah Humbert
Date Deposited: 12 Aug 2020 16:12
Last Modified: 10 Aug 2021 00:01

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