Charged Defects in UO2 Bulk and Surface: A First-Principles Study
Sandip Aryal1, Gaoxue Wang1, Enrique R Batista1
1Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.
ACS Applied Materials & Interfaces
|April 29, 2026
Summary
Defects in uranium dioxide (UO2) nuclear fuel create localized electronic states and alter magnetic behavior. Oxygen vacancies are more common at the surface, impacting nuclear fuel safety and efficiency.
Area of Science:
- Materials Science
- Nuclear Engineering
- Solid State Physics
Background:
- Uranium dioxide (UO2) is the primary fuel in nuclear reactors.
- Extreme reactor conditions (heat, radiation) cause crystal structure defects in UO2.
- Understanding these defects is crucial for nuclear fuel safety and performance.
Purpose of the Study:
- Investigate the nature and behavior of charged point defects in UO2.
- Examine defects in both bulk UO2 and its (111) surface.
- Determine the impact of defects on electronic structure, magnetism, and stability.
Main Methods:
- Density Functional Theory with the Hubbard U (DFT+U) correction was used.
- Calculations were performed for charged point defects in bulk UO2.
- Surface defect formation energies were analyzed for the UO2 (111) plane.
Main Results:
- Defects introduce localized electronic states and alter magnetic properties.
- Defects act as deep traps for charge carriers, affecting transport.
- Oxygen vacancies form more readily at the surface than in the bulk.
- Subsurface oxygen vacancies are more stable than surface vacancies.
Conclusions:
- Charged defects significantly influence magnetism, transport, and stability in UO2.
- Defect behavior is sensitive to the chemical environment and Fermi level.
- Findings provide insights for enhancing nuclear fuel safety and efficiency.
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