UO2
uranium dioxide · uranic oxide, uranium(IV) oxide
Uranium dioxide is a stable, metallic-behaving oxide widely utilized as a reliable fuel source in nuclear power generation.
About uranium dioxide
Uranium dioxide is a robust, thermodynamically stable compound that serves as a cornerstone material in the nuclear energy sector. Its structural integrity and ability to maintain a consistent phase under demanding conditions make it a primary choice for fuel fabrication in power reactors.
Characterized by its metallic electronic nature, this compound is highly valued for its predictable behavior and long-term stability. With a vast array of documented structural variations, it remains one of the most thoroughly investigated actinide oxides in materials science.
Key Properties
Cross-validated computational properties for uranium dioxide, aggregated across 3 databases.
Band GapEnergy needed to move an electron from the valence band to the conduction band. Lower or zero values tend to behave more metallic; larger gaps are more insulating or semiconducting.
Energy Above HullThermodynamic distance from the most stable set of competing phases. 0 eV/atom is on the convex hull; small positive values may still be experimentally accessible.
StabilityA plain-language summary of the best reported energy-above-hull result. It reflects whether the lowest-energy structure is on, near, or far from the stability hull.
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of UO2. Tight agreement means computed properties can be trusted without re-running calculations.
Agreement ScoreA normalized confidence score summarizing how closely independent DFT databases agree. Higher scores mean tighter cross-source agreement.
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
Reported Structures
Lowest-energy structures reported for UO2, ranked by energy above hull.
| Space GroupSymmetry classification of the crystal arrangement. The number is the international space-group index. | Crystal SystemBroad lattice family, such as cubic, tetragonal, monoclinic, or triclinic, derived from unit-cell symmetry. | Band Gap (eV)Electronic gap calculated for this specific reported structure, measured in electronvolts. | E above hull (eV/atom)Thermodynamic distance from the convex hull for this structure, normalized per atom. Lower is generally more stable. | E/atom (eV)Computed total energy normalized per atom. Use energy above hull, not this value alone, when comparing stability. | Density (g/cm³)Mass per relaxed crystal volume, reported in grams per cubic centimeter. |
|---|---|---|---|---|---|
| — | — | 2.47 | 0.0000 | -3.819 | — |
| Fm-3m (No. 225) | cubic | 0.00 | 0.0000 | -3.579 | — |
| Fm-3m (No. 225) | cubic | 0.00 | 0.0000 | -10.813 | 11.06 |
| — | — | 1.99 | 0.0105 | -3.809 | — |
| Fm-3m (No. 225) | cubic | 0.00 | 0.0270 | -3.552 | — |
| — | — | 8.43 | 0.1177 | -3.702 | — |
| P42/mnm (No. 136) | tetragonal | 0.00 | 0.1258 | -10.687 | 9.46 |
| — | — | 2.31 | 0.1351 | -3.684 | — |
| P42/mnm (No. 136) | tetragonal | 0.00 | 0.1996 | -3.379 | — |
| — | — | 1.18 | 0.2030 | -3.616 | — |
| — | — | 0.00 | 0.2662 | -3.553 | — |
| — | — | 0.00 | 0.3062 | -3.513 | — |
Synthesis Routes
Literature-extracted synthesis procedures targeting UO2.
Applications
Where uranium dioxide is used.
Patent Landscape
24 patents reference UO2 or close compositional variants.
| Patent | Title | Assignee | Granted |
|---|---|---|---|
| 4788048 | Process for conversion of UF.sub.6 to UO.sub.2 | — | — |
| 4117083 | Process for increasing the reaction rate of UO.sub.2 F.sub.2 | — | — |
| 4572810 | Method for providing uranium hydroxide on UO.sub.2 particles prior to generation of fugitive binder for sinter | — | — |
| 5417943 | Method for producing UO2 or (U/PU)02 powder | — | — |
| 4093783 | Novel formulations M.sub.2 UO.sub.2 F.sub.2 and their use in electrochemical cells | — | — |
| 3961027 | Cyclic process for re-use of waste water generated during the production of UO.sub.2 | — | — |
| 4119559 | UO.sub.2 F.sub.2 inclusion compositions | — | — |
| 9303298 | Porous UO2 sintered pellet for electroreduction process, and preparation method thereof | — | — |
| 3965237 | Dissolution process for ZrO.sub.2 -UO.sub.2 -CaO fuels | — | — |
| 5356605 | Recovery of UO.sub.2 /Pu O.sub.2 in IFR electrorefining process | — | — |
Frequently Asked Questions
Common questions about uranium dioxide, answered from cross-validated data.
What is UO2?
Uranium dioxide is a stable, metallic-behaving oxide widely utilized as a reliable fuel source in nuclear power generation.
What is UO2 used for?
What is the band gap of UO2?
Is UO2 a metal, semiconductor, or insulator?
Is UO2 thermodynamically stable?
What is the crystal structure of UO2?
How many polymorphs of UO2 are known?
How is UO2 synthesized?
What elements does UO2 contain?
Where does the data for UO2 come from?
How It Compares
As a fundamental actinide oxide, uranium dioxide stands as the primary benchmark for stability and performance in its class, setting the standard for how other heavy metal oxides are evaluated for industrial and radiological applications.
Data sources & attribution
- oqmd — Data from the OQMD (oqmd.org). Cite: Saal et al., JOM 65, 1501 (2013); Kirklin et al., npj Comp. Mater. 1, 15010 (2015). (CC-BY-4.0)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
- cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)
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