Ca2PI
Ca2PI is a stable, semiconducting inorganic compound composed of calcium, phosphorus, and iodine.
About Ca2PI
Ca2PI is a distinct inorganic compound characterized by its semiconducting electronic nature. As a thermodynamically stable material residing on the convex hull, it represents a robust configuration of calcium, phosphorus, and iodine atoms. Its structural integrity makes it a subject of interest for fundamental solid-state studies.
The compound is notable for its data-rich profile, with multiple reported structures across various databases. This diversity in structural arrangements highlights the complex bonding interactions present within the material, providing a foundation for future exploration in electronic and optoelectronic applications.
Key Properties
Cross-validated computational properties for Ca2PI, 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 Ca2PI. 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 Ca2PI, 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. |
|---|---|---|---|---|---|
| — | — | 1.81 | 0.0000 | -1.527 | — |
| R-3m (No. 166) | trigonal | 1.70 | 0.0000 | -4.242 | 3.31 |
| R-3m (No. 166) | trigonal | 1.67 | 0.0000 | -1.567 | — |
| R-3m (No. 166) | trigonal | 1.60 | 0.0118 | -1.555 | — |
| R-3m (No. 166) | trigonal | 1.60 | 0.0120 | -1.555 | — |
| P1 (No. 1) | triclinic | 1.60 | 0.0871 | -4.154 | 3.20 |
| R-3m (No. 166) | trigonal | — | — | — | 3.32 |
| P-1 (No. 2) | triclinic | — | — | — | 4.03 |
| P21/m (No. 11) | monoclinic | — | — | — | 3.17 |
| P21/m (No. 11) | monoclinic | — | — | — | 3.29 |
Applications
Where Ca2PI is used.
Frequently Asked Questions
Common questions about Ca2PI, answered from cross-validated data.
What is Ca2PI?
Ca2PI is a stable, semiconducting inorganic compound composed of calcium, phosphorus, and iodine.
What is Ca2PI used for?
What is the band gap of Ca2PI?
Is Ca2PI a metal, semiconductor, or insulator?
Is Ca2PI thermodynamically stable?
What is the crystal structure of Ca2PI?
What is the density of Ca2PI?
How many polymorphs of Ca2PI are known?
What elements does Ca2PI contain?
Where does the data for Ca2PI come from?
How It Compares
As a unique inorganic phase, Ca2PI serves as a representative example of complex ternary pnictide-halide systems. Without direct structural siblings in this specific class, it stands as a standalone reference point for understanding how the integration of alkaline earth metals with pnictogen and halogen elements influences electronic behavior and structural stability.
Data sources & attribution
- 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)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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