UO3
uranium trioxide · uranyl oxide
Uranium trioxide is a stable, semiconducting uranium oxide widely used as a chemical intermediate in nuclear fuel production.
About uranium trioxide
Uranium trioxide is a thermodynamically stable oxide that serves as a critical intermediate in the processing and refinement of uranium. As a semiconducting material, it exhibits complex structural chemistry, with numerous distinct phases identified through extensive experimental and computational research.
Its significance lies primarily in its role within the nuclear fuel cycle, where it acts as a precursor for the production of other uranium compounds. The material's stability and chemical versatility make it a focal point for understanding actinide oxide behavior in industrial and geological contexts.
Key Properties
Cross-validated computational properties for uranium trioxide, 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 UO3. 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 UO3, 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. |
|---|---|---|---|---|---|
| — | — | 2.93 | 0.0000 | -3.131 | — |
| Pm-3m (No. 221) | cubic | 1.81 | 0.0000 | -3.225 | — |
| Pm-3m (No. 221) | cubic | 1.63 | 0.0000 | -10.146 | 6.72 |
| P212121 (No. 19) | orthorhombic | 1.97 | 0.0097 | -3.215 | — |
| P-3m1 (No. 164) | trigonal | 1.87 | 0.0219 | -3.203 | — |
| — | — | 2.54 | 0.0256 | -3.105 | — |
| — | — | 3.09 | 0.0275 | -3.104 | — |
| — | — | 2.45 | 0.0408 | -3.090 | — |
| I41/amd (No. 141) | tetragonal | 1.89 | 0.0822 | -10.064 | 7.72 |
| Fddd (No. 70) | orthorhombic | 1.88 | 0.0828 | -10.063 | 7.69 |
| P212121 (No. 19) | orthorhombic | 1.91 | 0.0830 | -10.063 | 8.63 |
| — | — | 2.25 | 0.0963 | -3.035 | — |
Applications
Where uranium trioxide is used.
Patent Landscape
2 patents reference UO3 or close compositional variants.
| Patent | Title | Assignee | Granted |
|---|---|---|---|
| 8628733 | Method for preparing uranium concentrates by fluidized bed precipitation, and preparation of UO3 and U3O8 by d | — | — |
| 9045350 | Method for converting UO3 or U3O8 into hydrated UO4 | — | — |
Frequently Asked Questions
Common questions about uranium trioxide, answered from cross-validated data.
What is UO3?
Uranium trioxide is a stable, semiconducting uranium oxide widely used as a chemical intermediate in nuclear fuel production.
What is UO3 used for?
What is the band gap of UO3?
Is UO3 a metal, semiconductor, or insulator?
Is UO3 thermodynamically stable?
What is the crystal structure of UO3?
How many polymorphs of UO3 are known?
What elements does UO3 contain?
Where does the data for UO3 come from?
How It Compares
As a fundamental oxide in uranium chemistry, uranium trioxide stands as a primary reference point for actinide-based materials. It represents a stable endpoint in the oxidation of uranium, serving as a key benchmark for evaluating the structural and electronic properties of higher-order uranium oxides.
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.
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