KHF2
potassium bifluoride · potassium acid fluoride
Potassium bifluoride is a stable, insulating salt primarily used as a source of fluoride for industrial fluxing, glass etching, and chemical manufacturing.
About potassium bifluoride
Potassium bifluoride is a robust, thermodynamically stable inorganic compound characterized by its insulating electronic properties. It serves as a vital source of fluoride ions in various chemical processes, maintaining structural integrity across diverse environmental conditions.
Due to its chemical nature, this compound is widely employed in metallurgical applications, particularly as a flux for soldering and brazing. Its ability to provide a controlled release of fluoride makes it an essential reagent in the production of specialized glass and in industrial surface treatment processes.
Key Properties
Cross-validated computational properties for potassium bifluoride, 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 KHF2. 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 KHF2, 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. |
|---|---|---|---|---|---|
| — | — | 7.83 | 0.0000 | -2.466 | — |
| I4/mcm (No. 140) | tetragonal | 7.41 | 0.0000 | -2.376 | — |
| I4/mcm (No. 140) | tetragonal | 6.97 | 0.0000 | -4.581 | 2.47 |
| — | — | 7.61 | 0.0939 | -2.372 | — |
| I4/mcm (No. 140) | tetragonal | — | — | — | 2.37 |
| P-1 (No. 2) | triclinic | — | — | — | 2.26 |
| I4/mcm (No. 140) | tetragonal | — | — | — | 2.37 |
| P-1 (No. 2) | triclinic | — | — | — | 1.28 |
| P-1 (No. 2) | triclinic | — | — | — | 1.46 |
Applications
Where potassium bifluoride is used.
Frequently Asked Questions
Common questions about potassium bifluoride, answered from cross-validated data.
What is KHF2?
Potassium bifluoride is a stable, insulating salt primarily used as a source of fluoride for industrial fluxing, glass etching, and chemical manufacturing.
What is KHF2 used for?
What is the band gap of KHF2?
Is KHF2 a metal, semiconductor, or insulator?
Is KHF2 thermodynamically stable?
What is the crystal structure of KHF2?
How many polymorphs of KHF2 are known?
What elements does KHF2 contain?
Where does the data for KHF2 come from?
How It Compares
As a standalone member of its chemical class, potassium bifluoride is recognized for its exceptional thermodynamic stability, which distinguishes it as a reliable and well-characterized material compared to less stable or more reactive fluoride-based alternatives.
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)
- 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)
- 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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