SiI2
SiI2 is a metastable semiconducting compound composed of silicon and iodine that is studied for its structural properties in the context of silicon-based materials.
About SiI2
SiI2 is a metastable silicon-iodide compound that functions within the broader landscape of silicon-based materials. As a semiconducting species, it represents a unique structural configuration that researchers study to understand phase stability and potential electrochemical pathways in energy storage systems.
Its significance lies in the diverse structural possibilities inherent to silicon-iodide chemistry. By investigating this compound, scientists gain insights into the fundamental behavior of silicon-based anodes, contributing to the development of more robust materials for next-generation battery architectures.
Key Properties
Cross-validated computational properties for SiI2, 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 SiI2. 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 SiI2, 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. |
|---|---|---|---|---|---|
| P21/c (No. 14) | monoclinic | 2.29 | 0.0259 | -3.382 | 3.16 |
| Pm (No. 6) | monoclinic | 0.70 | 0.2455 | -0.036 | — |
| — | — | 0.49 | 0.3258 | -0.116 | — |
| Pmm2 (No. 25) | orthorhombic | 0.47 | 0.4863 | 0.205 | — |
| — | — | 0.63 | 0.6133 | 0.171 | — |
| — | — | 0.00 | 1.6609 | 1.219 | — |
| P-1 (No. 2) | triclinic | — | — | — | 9.04 |
| P-1 (No. 2) | triclinic | — | — | — | 4.19 |
| P1 (No. 1) | triclinic | — | — | — | 5.51 |
| P1 (No. 1) | triclinic | — | — | — | 3.20 |
| P1 (No. 1) | triclinic | — | — | — | 3.59 |
| P1 (No. 1) | triclinic | — | — | — | 3.79 |
Applications
Where SiI2 is used.
Frequently Asked Questions
Common questions about SiI2, answered from cross-validated data.
What is SiI2?
SiI2 is a metastable semiconducting compound composed of silicon and iodine that is studied for its structural properties in the context of silicon-based materials.
What is SiI2 used for?
What is the band gap of SiI2?
Is SiI2 a metal, semiconductor, or insulator?
Is SiI2 thermodynamically stable?
What is the crystal structure of SiI2?
What is the density of SiI2?
How many polymorphs of SiI2 are known?
What elements does SiI2 contain?
Where does the data for SiI2 come from?
How It Compares
Within the silicon anode materials class.
Unlike the highly stable and widely utilized elemental silicon or the robust silicides like MoSi2 and Mg2Si, SiI2 exists in a metastable state. While compounds such as BaSi2 are frequently explored for their specific optoelectronic properties, SiI2 is primarily examined for its structural complexity and the role of iodine in modifying the silicon framework compared to more conventional metal silicides.
Related Compounds
Other Silicon Anode Materials in the database.
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.
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