BiI
BiI is a metastable semiconducting binary compound consisting of bismuth and iodine.
About BiI
BiI is a metastable semiconducting compound composed of bismuth and iodine. Its existence as a distinct phase highlights the complex bonding interactions possible between heavy p-block elements and halogens, making it a subject of significant interest for structural researchers.
Due to its metastable nature, this material is often studied to understand the phase space of bismuth-based halides. It serves as an important entry in materials informatics, where its numerous reported structural variations provide insights into the stability limits of simple binary systems.
Key Properties
Cross-validated computational properties for BiI, aggregated across 6 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 BiI. 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 BiI, 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. |
|---|---|---|---|---|---|
| C2/m (No. 12) | monoclinic | 0.82 | 0.0200 | -0.296 | — |
| C2/m (No. 12) | monoclinic | 0.56 | 0.0212 | -0.294 | — |
| — | — | 0.73 | 0.0266 | -0.379 | — |
| C2/m (No. 12) | monoclinic | 0.83 | 0.0270 | -3.191 | 6.37 |
| C2/m (No. 12) | monoclinic | 0.93 | 0.0279 | -3.190 | 6.45 |
| — | — | 0.66 | 0.0299 | -0.376 | — |
| Cm (No. 8) | monoclinic | 0.00 | 0.2010 | -0.115 | — |
| — | — | 0.00 | 0.3000 | -0.106 | — |
| P4/mmm (No. 123) | tetragonal | 0.00 | 0.3605 | 0.045 | — |
| — | — | 0.00 | 0.4158 | 0.010 | — |
| — | — | 0.00 | 0.4639 | 0.058 | — |
| Fm-3m (No. 225) | cubic | 0.00 | 0.5506 | 0.235 | — |
Applications
Where BiI is used.
Frequently Asked Questions
Common questions about BiI, answered from cross-validated data.
What is BiI?
BiI is a metastable semiconducting binary compound consisting of bismuth and iodine.
What is BiI used for?
What is the band gap of BiI?
Is BiI a metal, semiconductor, or insulator?
Is BiI thermodynamically stable?
What is the crystal structure of BiI?
How many polymorphs of BiI are known?
What elements does BiI contain?
Where does the data for BiI come from?
How It Compares
As a unique binary bismuth iodide, BiI occupies a specific niche in the landscape of inorganic halides, representing a metastable configuration that contrasts with more common, thermodynamically stable bismuth triiodide phases.
Data sources & attribution
- 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)
- 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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