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.

FHK
Crystal structure of KHF2 (tetragonal, I4/mcm (No. 140))
Ground-state structure · Materials Project
Overview

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.

At a glance

Key Properties

Cross-validated computational properties for potassium bifluoride, aggregated across 3 databases.

Band Gap

6.97 eV
Range across DFT structures

Energy Above Hull

0.000 eV/atom
Best (lowest) across sources

Stability

On hull (stable)
2 DFT sources

Structures

5
3 databases, 2 space groups
Crystallography

Reported Structures

Lowest-energy structures reported for KHF2, ranked by energy above hull.

Space GroupCrystal SystemBand Gap (eV)E above hull (eV/atom)E/atom (eV)Density (g/cm³)
I4/mcm (No. 140)tetragonal6.970.0000-4.5812.47
P-1 (No. 2)Triclinic1.28
P-1 (No. 2)Triclinic1.46
P-1 (No. 2)Triclinic2.26
I4/mcm (No. 140)
Uses

Applications

Where potassium bifluoride is used.

soldering fluxbrazing fluxglass etchingfluorinating agentwood preservation
Reference

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.

More questions
What is KHF2 used for?
potassium bifluoride (KHF2) is used in soldering flux, brazing flux, glass etching, fluorinating agent, and wood preservation.
What is the band gap of KHF2?
potassium bifluoride (KHF2) has a DFT-computed band gap of 6.97 eV across 5 reported structures.
Is KHF2 a metal, semiconductor, or insulator?
With a wide band gap up to 6.97 eV it is an insulator / wide-band-gap material.
Is KHF2 thermodynamically stable?
Yes — potassium bifluoride (KHF2) sits on the convex hull (energy above hull 0 eV/atom), i.e. on hull (stable).
What is the crystal structure of KHF2?
The lowest-energy reported polymorph of potassium bifluoride (KHF2) is tetragonal symmetry, space group I4/mcm (No. 140).
What is the density of KHF2?
The computed density of the ground-state structure of potassium bifluoride (KHF2) is 2.47 g/cm³.
How many polymorphs of KHF2 are known?
5 structures of KHF2 are reported across 3 databases, spanning 2 distinct space groups.
What elements does KHF2 contain?
potassium bifluoride (KHF2) contains F, H, and K (3 elements).
Where does the data for KHF2 come from?
KHF2 data is cross-referenced from materials_project, mpaloe, jarvis.
Comparison

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
  • materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
  • mpaloe — Data from mpaloe.
  • jarvis — Data from JARVIS (NIST). Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020).

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