Point defects and impurities in fluorite PuO₂

Journal Article · Mon Mar 16 00:00:00 UTC 2026 · Physical Review Materials

DOI: https://doi.org/10.1103/7p4w-38fj · OSTI ID:3024688

Rowberg, Andrew J. E.  ^[1]; Kweon, Kyoung Eun ^[1]; Donald, Scott B.  ^[1]

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1. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

The native surface oxide of plutonium plays a critical role in ensuring the stability and safe storage of the underlying metal; consequently, understanding the role of defects and impurities in determining the properties of the oxide layer is critical. Here, in this study, we use hybrid density-functional theory calculations to evaluate the electronic structure and defect chemistry of PuO₂, the most stable of the native oxide phases, including both native and extrinsic defects. We find that oxygen vacancies (𝑉_O) form readily in PuO₂, as do polarons. Electron polarons (𝜂⁻) are the lowest-energy acceptor species in PuO₂, while the charge compensating donor species will shift from 𝑉_O under O-poor conditions to hole polarons (𝜂⁺) under O-rich conditions. Nitrogen and fluorine can substitute readily for oxygen atoms under O-poor conditions, while fluorine can also incorporate in an interstitial configuration (F$$^−_i$$) under more O-rich conditions. Carbon and chlorine incorporation in PuO₂ will be very limited. We also evaluate the kinetic barriers for oxygen-related defects, which we find to diffuse readily when present. Our results provide valuable insights into the critical role and variable chemistry of point defects and impurities in PuO₂, which in turn have important implications for the safe storage of the underlying metal layer. In short, exposure of freshly prepared plutonium to reactive nitrogen- and fluorine-containing contaminants should be avoided, while carbon- or chlorine-containing contaminants are less likely to incorporate readily into the oxide.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 3024688
• Report Number(s): LLNL-JRNL-2013660
• Journal Information: Physical Review Materials, Journal Name: Physical Review Materials Journal Issue: 3 Vol. 10; ISSN 2475-9953
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English