K2AlF5
K2AlF5 is a thermodynamically stable, insulating fluoride compound composed of potassium, aluminum, and fluorine.
About K2AlF5
K2AlF5 is a complex fluoride compound characterized by its wide-gap insulating electronic nature. As a thermodynamically stable phase located on the convex hull, it represents a robust structural arrangement of potassium, aluminum, and fluorine atoms.
This material is of interest for its structural stability and fundamental properties within the broader family of metal fluorides. Its existence across multiple reported structures highlights its significance as a well-defined inorganic compound for academic and materials research.
Key Properties
Cross-validated computational properties for K2AlF5, 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 K2AlF5. 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 K2AlF5, 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. |
|---|---|---|---|---|---|
| P4/mmm (No. 123) | tetragonal | 6.62 | 0.0000 | -3.438 | — |
| P4/mmm (No. 123) | tetragonal | 6.33 | 0.0000 | -5.457 | 2.60 |
| — | — | 7.03 | 0.0026 | -3.471 | — |
| — | — | 7.15 | 0.0039 | -3.470 | — |
| P4/mmm (No. 123) | tetragonal | — | — | — | 2.53 |
| P4/mmm (No. 123) | tetragonal | — | — | — | 2.51 |
| P4/mmm (No. 123) | tetragonal | — | — | — | 2.43 |
| P4/mmm (No. 123) | tetragonal | — | — | — | 2.55 |
Applications
Where K2AlF5 is used.
Frequently Asked Questions
Common questions about K2AlF5, answered from cross-validated data.
What is K2AlF5?
K2AlF5 is a thermodynamically stable, insulating fluoride compound composed of potassium, aluminum, and fluorine.
What is K2AlF5 used for?
What is the band gap of K2AlF5?
Is K2AlF5 a metal, semiconductor, or insulator?
Is K2AlF5 thermodynamically stable?
What is the crystal structure of K2AlF5?
How many polymorphs of K2AlF5 are known?
What elements does K2AlF5 contain?
Where does the data for K2AlF5 come from?
How It Compares
As a stable inorganic fluoride, K2AlF5 serves as a representative example of how alkali and aluminum cations coordinate with fluorine to form insulating, structurally reliable frameworks.
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)
- 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)
- 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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