TlI
Thallium(I) iodide · Thallous iodide
Thallium(I) iodide is a stable semiconducting inorganic compound frequently utilized in specialized radiation detection and optical technologies.
About Thallium(I) iodide
Thallium(I) iodide is a thermodynamically stable compound that exists as a semiconducting material. Its structural versatility is evidenced by the extensive number of reported phases found in materials databases, highlighting its complex behavior under varying conditions. This compound is primarily valued for its electronic properties, which make it a candidate for specialized applications in high-energy physics and optics. Its stability on the convex hull ensures it remains a reliable subject for fundamental research into thallium-based semiconductors.
Key Properties
Cross-validated computational properties for Thallium(I) iodide, 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 TlI. 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 TlI, 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. |
|---|---|---|---|---|---|
| Fm-3m (No. 225) | cubic | 2.21 | 0.0000 | -2.814 | 6.30 |
| Cmcm (No. 63) | orthorhombic | 2.20 | 0.0000 | -0.672 | — |
| Cmcm (No. 63) | orthorhombic | 2.15 | 0.0008 | -2.813 | 6.86 |
| — | — | 2.17 | 0.0008 | -0.762 | — |
| Fm-3m (No. 225) | cubic | 2.12 | 0.0013 | -0.671 | — |
| Pm-3m (No. 221) | cubic | 2.04 | 0.0088 | -0.664 | — |
| Pm-3m (No. 221) | cubic | 1.81 | 0.0208 | -2.793 | 7.23 |
| — | — | 2.13 | 0.0259 | -0.737 | — |
| P-6m2 (No. 187) | hexagonal | 1.58 | 0.0316 | -0.641 | — |
| — | — | 1.79 | 0.0510 | -0.712 | — |
| — | — | 3.10 | 0.0806 | -0.683 | — |
| — | — | 1.09 | 0.0812 | -0.682 | — |
Applications
Where Thallium(I) iodide is used.
Frequently Asked Questions
Common questions about Thallium(I) iodide, answered from cross-validated data.
What is TlI?
Thallium(I) iodide is a stable semiconducting inorganic compound frequently utilized in specialized radiation detection and optical technologies.
What is TlI used for?
What is the band gap of TlI?
Is TlI a metal, semiconductor, or insulator?
Is TlI thermodynamically stable?
What is the crystal structure of TlI?
How many polymorphs of TlI are known?
What elements does TlI contain?
Where does the data for TlI come from?
How It Compares
As a standalone member of its class in this context, thallium(I) iodide serves as a foundational example of a stable, semiconducting thallium halide. It represents a critical reference point for understanding how heavy metal cations influence the electronic and structural landscape of inorganic iodides.
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)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- 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)
- 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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