UI4
Uranium tetraiodide is a stable, semiconducting uranium-iodine compound used in fundamental materials research.
About UI4
Uranium tetraiodide is a distinct inorganic compound composed of uranium and iodine. As a thermodynamically stable material situated on the convex hull, it represents a well-defined chemical species within its structural group.
Characterized as a semiconductor, this compound is of interest for its electronic properties and structural versatility. Its existence across multiple reported structures highlights its significance in fundamental materials research and actinide chemistry.
Key Properties
Cross-validated computational properties for UI4, 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 UI4. 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 UI4, 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. |
|---|---|---|---|---|---|
| — | — | 1.54 | 0.0000 | -0.969 | — |
| C2/c (No. 15) | monoclinic | 0.28 | 0.0000 | -0.840 | — |
| C2/c (No. 15) | monoclinic | 0.26 | 0.0000 | -4.628 | 5.17 |
| C2/c (No. 15) | monoclinic | 0.28 | 0.0045 | -0.836 | — |
| C2/c (No. 15) | monoclinic | 0.17 | 0.0501 | -4.577 | 3.72 |
| C2/c (No. 15) | monoclinic | — | — | — | 5.57 |
| C2/c (No. 15) | monoclinic | — | — | — | 16.29 |
| C2/c (No. 15) | monoclinic | — | — | — | 4.80 |
| C2/c (No. 15) | monoclinic | — | — | — | 3.72 |
| C2/c (No. 15) | monoclinic | — | — | — | 3.72 |
| C2/c (No. 15) | monoclinic | — | — | — | 3.72 |
| C2/c (No. 15) | monoclinic | — | — | — | 4.83 |
Applications
Where UI4 is used.
Frequently Asked Questions
Common questions about UI4, answered from cross-validated data.
What is UI4?
Uranium tetraiodide is a stable, semiconducting uranium-iodine compound used in fundamental materials research.
What is UI4 used for?
What is the band gap of UI4?
Is UI4 a metal, semiconductor, or insulator?
Is UI4 thermodynamically stable?
What is the crystal structure of UI4?
How many polymorphs of UI4 are known?
What elements does UI4 contain?
Where does the data for UI4 come from?
How It Compares
As a standalone entry in this context, uranium tetraiodide serves as a primary reference point for uranium-iodine systems. Its stability and semiconducting nature provide a benchmark for understanding the bonding and electronic behavior of heavy metal halides.
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)
- cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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