Potassium Fluorosilicate

Potassium Fluorosilicate

Potassium fluorosilicate is a chemical compound with the chemical formula K2[SiF6]. When doped with Potassium hexafluoromanganate(IV) ((K2[MnF6]) it forms a narrow band red producing phosphor, (often abbreviated PSF or KSF), of economic interest due to its applicability in LED lighting and displays.

Potassium fluorosilicate is primarily used as a source of fluoride ions in various applications, including metal surface treatment, wood preservation, and insecticides. It is also utilized in the production of synthetic cryolite, a compound used in the aluminum smelting process.


  • Chemical formula: K2[SiF6]
  • Molar mass: 220.28 gmol−1
  • Density: 2.27gcm−3, 2.719gcm−3
  • Solubility in water: Slightly soluble in water
  • Crystal structure: cubic

Natural occurrence

Occurs naturally as Hiereatite, found in the Aeolian islands (Sicily/Italy). A hexagonal form Demartinite has also been found at the rim of volcanic fumaroles in the same islands.

Potassium fluorosilicate is toxic if ingested or inhaled. It releases toxic hydrogen fluoride gas upon contact with strong acids or at high temperatures, so proper precautions should be taken when handling or using this compound. It should be stored in a dry place away from moisture, acids, and incompatible materials.

Structure and properties

Potassium fluorosilicate has the ability to etch glass and is sometimes used in the manufacturing of glassware. According to analysis by (Loehlin, 1984) it has space group Fm3m, with a0 = 0.8134 nm, V = 0.538.2 nm3 at 295K. The Si-F bond length is 0.1683 nm. At high temperatures and pressures -beta and -gamma phases exist.


Potassium fluorosilicate has applications in porcelain manufacture, the preservation of timber, aluminium and magnesium smelting, and the manufacture of optical glass. It is sometimes used as a source of fluoride ions for water fluoridation.

  • It is used in metal surface treatment processes, such as aluminum anodizing, to enhance corrosion resistance.
  • It is used as a wood preservative to protect against decay and insect damage.
  • It can be used as a fluorinating agent or as a precursor for other fluoride compounds.
  • It is sometimes added to glass formulations to improve the glass’s resistance to thermal shock.


Potassium fluorosilicate is toxic if ingested or inhaled in large quantities. It can release toxic hydrogen fluoride gas when heated.