PI2
PI2 is a thermodynamically stable, semiconducting binary compound formed from phosphorus and iodine.
About PI2
PI2 is a phosphorus-iodine compound characterized by its semiconducting electronic nature. As a thermodynamically stable phase located on the convex hull, it represents a robust configuration of these elements, making it a subject of significant interest for structural analysis and material modeling.
Given its status as a well-documented material with numerous reported structures across databases, PI2 serves as a key reference point for understanding phosphorus-iodine bonding environments. Its stability suggests potential for applications where consistent electronic behavior is required.
Key Properties
Cross-validated computational properties for PI2, 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 PI2. 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 PI2, 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. |
|---|---|---|---|---|---|
| P-1 (No. 2) | triclinic | 2.02 | 0.0000 | -3.135 | 3.90 |
| — | — | 1.89 | 0.0000 | -0.253 | — |
| P-1 (No. 2) | triclinic | 1.59 | 0.0000 | -0.050 | — |
| C2 (No. 5) | monoclinic | 0.00 | 0.2426 | 0.192 | — |
| Pmm2 (No. 25) | orthorhombic | 0.00 | 0.2680 | 0.218 | — |
| Pm (No. 6) | monoclinic | 0.00 | 0.2750 | 0.225 | — |
| — | — | 0.00 | 0.2752 | 0.022 | — |
| — | — | 0.00 | 0.3501 | 0.097 | — |
| P6/mmm (No. 191) | hexagonal | 0.00 | 0.8827 | 0.832 | — |
| — | — | 0.00 | 1.6038 | 1.350 | — |
| P-1 (No. 2) | triclinic | — | — | — | 2.91 |
| P1 (No. 1) | triclinic | — | — | — | 3.25 |
Applications
Where PI2 is used.
Frequently Asked Questions
Common questions about PI2, answered from cross-validated data.
What is PI2?
PI2 is a thermodynamically stable, semiconducting binary compound formed from phosphorus and iodine.
What is PI2 used for?
What is the band gap of PI2?
Is PI2 a metal, semiconductor, or insulator?
Is PI2 thermodynamically stable?
What is the crystal structure of PI2?
What is the density of PI2?
How many polymorphs of PI2 are known?
What elements does PI2 contain?
Where does the data for PI2 come from?
How It Compares
As a distinct phosphorus-iodine compound, PI2 occupies a unique position in materials research. Without direct siblings in this specific class, it serves as a primary example of how these elements can form stable, semiconducting architectures, providing a benchmark for future exploration of similar binary systems.
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.
- 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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