Potassium fluorosilicate

Potassium fluorosilicate
Names
	Preferred IUPAC name Potassium fluorosilicate
	Other names Potassium hexafluorosilicate(IV)
Identifiers
CAS Number	16871-90-2;
3D model (JSmol)	Interactive image;
ChemSpider	55723;
ECHA InfoCard	100.037.163
EC Number	240-896-2 ;
PubChem CID	61851;
RTECS number	VV8400000;
UNII	2610W49XYD;
UN number	2655
CompTox Dashboard (EPA)	DTXSID10884939 ;
	InChI InChI=1S/F6Si.2K/c1-7(2,3,4,5)6;;/q-2;2*+1 Key: UUHPPUWEDCVPCO-UHFFFAOYSA-N;
	SMILES F[Si-2](F)(F)(F)(F)F.[K+].[K+];
Properties
Chemical formula	K2[SiF6]
Molar mass	220.28 g·mol−1
Density	2.27 g·cm−3, 2.719 g·cm−3
Solubility in water	Slightly soluble in water
Structure
Crystal structure	cubic
Space group	Fm3m
Lattice constant	a = 0.8134 nm
Lattice volume (V)	0.538.2 nm3
Formula units (Z)	4
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H311, H331
Precautionary statements	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). Infobox references

Potassium fluorosilicate is a chemical compound with the chemical formula K₂[SiF₆].

When doped with potassium hexafluoromanganate(IV) (K₂[MnF₆], with Mn⁴⁺) 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 295 K. The Si-F bond length is 0.1683 nm.^[2] At high temperatures and pressures -beta and -gamma phases exist.^[5]

Applications

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]

References

^ ^a ^b ^c ^d "44495 Potassium hexafluorosilicate, 99.999 % (metals basis)", www.alfa.com
^ ^a ^b Loehlin, J. H. (1984), "Redetermination of the structure of potassium hexafluorosilicate, K₂SiF₆", Acta Crystallographica, C40 (3): 570, Bibcode:1984AcCrC..40..570L, doi:10.1107/S0108270184004893
^ "Hieratit", www.mineralienatlas.de
^ 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
^ ^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
^ 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
^ Happich, Julien (20 Nov 2017), "Differentiate or loose! Yole's analysis on LED phosphors and QDs", www.eenewseurope.com

[alfa-1] "44495 Potassium hexafluorosilicate, 99.999 % (metals basis)", www.alfa.com

[loehlin-2] Loehlin, J. H. (1984), "Redetermination of the structure of potassium hexafluorosilicate, K₂SiF₆", Acta Crystallographica, C40 (3): 570, Bibcode:1984AcCrC..40..570L, doi:10.1107/S0108270184004893

[Hieratit-3] "Hieratit", www.mineralienatlas.de

[Demartinite-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

[phosphor2018-5] 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

[phosphor2017-6] 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

[Happich2017-7] Happich, Julien (20 Nov 2017), "Differentiate or loose! Yole's analysis on LED phosphors and QDs", www.eenewseurope.com

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