Potassium fluorosilicate
Preferred IUPAC name
Potassium fluorosilicate
Other names
Potassium hexafluorosilicate(IV)
3D model (JSmol)
ECHA InfoCard 100.037.163 Edit this at Wikidata
EC Number
RTECS number
  • VV8400000
UN number 2655
  • InChI=1S/F6Si.2K/c1-7(2,3,4,5)6;;/q-2;2*+1
  • F[Si-2](F)(F)(F)(F)F.[K+].[K+]
Molar mass 220.28 gmol−1 [1]
Density 2.27gcm−3,[1] 2.719gcm−3 [2]
Slightly soluble in water
a = 0.8134 nm
0.538.2 nm3
GHS labelling:
GHS06: Toxic
H301, H311, H331
P261, P264, P270, P271, P280, P301+P310, P302+P352, P304+P340, P311, P312, P321, P322, P330, P361, P363, P403+P233, P405, P501
Related compounds
Other cations
Ammonium hexafluorosilicate
Sodium fluorosilicate

Fluorosilicic acid

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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.

Natural occurrence

Occurs naturally as Hiereatite, found in the Aeolian islands (Sicily/Italy).[3] A hexagonal form Demartinite has also been found at the rim of volcanic fumaroles in the same islands.[4]

Structure and properties

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.[2] At high temperatures and pressures -beta and -gamma phases exist.[5]


Potassium fluorosilicate has applications in porcelain manufacture, the preservation of timber, aluminium and magnesium smelting, and the manufacture of optical glass.[1]

Red phosphor

When doped with potassium hexafluoromanganate(IV) (K2[MnF6]), a narrow band red phosphor is produced, emitting at around 630 nm. This substance has application improving the white light quality of white LEDs that use a blue emitting LED in combination with the yellow cerium doped yttrium aluminium garnet phosphor (YAG), Y3Al5O12:Ce3+.[6]

Synthesis routes to the phosphor include co-crystallisation and co-precipitation. For example, K2[MnF6] in (40%) hydrofluoric acid with potassium fluoride can be mixed with SiO2 dissolved in (40%) hydrofluoric acid to co-precipitate the phosphor.[5]

The acronyms KSF or PSF are used for potassium fluorosilicate phosphors.[7]

See also


  1. ^ a b c d "44495 Potassium hexafluorosilicate, 99.999% (metals basis)", www.alfa.com
  2. ^ a b Loehlin, J. H. (1984), "Redetermination of the structure of potassium hexafluorosilicate, K2SiF6", Acta Crystallogr., C40 (3): 570, Bibcode:1984AcCrC..40..570L, doi:10.1107/S0108270184004893
  3. ^ "Hieratit", www.mineralienatlas.de
  4. ^ GRAMACCIOLIß, CARLO MARIA; CAMPOSTRINI, ITALO (2007), "DEMARTINITE, A NEW POLYMORPH OF K2SiF6 FROM LA FOSSA CRATER, VULCANO, AEOLIAN ISLANDS, ITALY", The Canadian Mineralogist, 45 (5): 1275–1280, Bibcode:2007CaMin..45.1275G, doi:10.2113/gscanmin.45.5.1275
  5. ^ a b Verstraete, Reinert; Sijbom, Heleen F.; Joos, Jonas J.; Korthout, Katleen; Poelman, Dirk; Detavernier, Christophe; Smet, Philippe F. (2018), "Red Mn4+-Doped Fluoride Phosphors: Why Purity Matters" (PDF), ACS Applied Materials & Interfaces, 10 (22): 18845–18856, doi:10.1021/acsami.8b01269, PMID 29750494
  6. ^ SIJBOM, HELEEN F.; VERSTRAETE, REINERT; JOOS, JONAS J.; POELMAN, DIRK; SMET, PHILIPPE F. (1 Sep 2017), "K2SiF6:Mn4+ as a red phosphor for displays and warm-white LEDs: a review of properties and perspectives", Optical Materials Express, 7 (9): 3332, Bibcode:2017OMExp...7.3332S, doi:10.1364/OME.7.003332
  7. ^ Happich, Julien (20 Nov 2017), "Differentiate or loose! Yole's analysis on LED phosphors and QDs", www.eenewseurope.com