AcI3
Actinium triiodide is a thermodynamically stable, semiconducting actinide halide used primarily in fundamental research.
About AcI3
Actinium triiodide is a thermodynamically stable compound that occupies a distinct position within actinide halide chemistry. As a semiconducting material, it serves as a fundamental subject for researchers investigating the electronic and structural properties of actinium-based systems.
With extensive structural data available across multiple databases, this compound provides critical insights into the behavior of heavy elements. Its stability and well-characterized nature make it an essential reference point for understanding the periodic trends of the actinide series.
Key Properties
Cross-validated computational properties for AcI3, aggregated across 4 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 AcI3. 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 AcI3, 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. |
|---|---|---|---|---|---|
| P63/mmc (No. 194) | hexagonal | 2.59 | 0.0000 | -3.974 | 4.33 |
| — | — | 2.31 | 0.0000 | -1.628 | — |
| P63/mmc (No. 194) | hexagonal | 2.04 | 0.0000 | -1.489 | — |
| C2/m (No. 12) | monoclinic | 2.54 | 0.0081 | -1.481 | — |
| — | — | 1.48 | 0.2830 | -1.345 | — |
| — | — | 1.79 | 0.2971 | -1.331 | — |
| — | — | 0.62 | 0.4564 | -1.171 | — |
| P1 (No. 1) | triclinic | — | — | — | 8.75 |
| P1 (No. 1) | triclinic | — | — | — | 5.91 |
| Cmcm (No. 63) | orthorhombic | — | — | — | 12.46 |
| P63/mmc (No. 194) | hexagonal | — | — | — | 3.97 |
| P1 (No. 1) | triclinic | — | — | — | 4.34 |
Applications
Where AcI3 is used.
Frequently Asked Questions
Common questions about AcI3, answered from cross-validated data.
What is AcI3?
Actinium triiodide is a thermodynamically stable, semiconducting actinide halide used primarily in fundamental research.
What is AcI3 used for?
What is the band gap of AcI3?
Is AcI3 a metal, semiconductor, or insulator?
Is AcI3 thermodynamically stable?
What is the crystal structure of AcI3?
What is the density of AcI3?
How many polymorphs of AcI3 are known?
What elements does AcI3 contain?
Where does the data for AcI3 come from?
How It Compares
As a unique actinide triiodide, AcI3 serves as a primary reference point for the study of actinium halides, providing foundational data for the broader exploration of heavy metal chemistry.
Data sources & attribution
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- 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)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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