Potassium fluorosilicate

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

Potassium fluorosilicate
Names
Preferred IUPAC name
Potassium fluorosilicate
Other names
Potassium hexafluorosilicate(IV)
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.037.163
EC Number
RTECS number
  • VV8400000
UNII
UN number 2655
Properties
K2[SiF6]
Molar mass 220.28 gmol−1 [1]
Density 2.27gcm−3,[1] 2.719gcm−3 [2]
Slightly soluble in water
Structure
cubic
Fm3m
a = 0.8134 nm
0.538.2 nm3
4
Hazards
GHS pictograms
GHS Signal word Danger
H301, H311, H331
P261, P264, P270, P271, P280, P301+310, P302+352, P304+340, P311, P312, P321, P322, P330, P361, P363, P403+233, 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

When doped with Potassium hexfluoromangante(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]

Application

Potassium fluorosilicate has applications including : porcelain manufacture; preservation of timber; aluminium and magnesium production (smelting); intermediate in the manufacture of optical glass.[1]

Red phosphor

When doped with potassium hexfluoromangante(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 phoshor (YAG), Y3Al5O12:Ce3+.[6]

Synthesis routes to the phoshpor 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 phoshpors.[7]

See also

References
  1. "44495 Potassium hexafluorosilicate, 99.999% (metals basis)", www.alfa.com
  2. Loehlin, J. H. (1984), "Redetermination of the structure of potassium hexafluorosilicate, K2SiF6", Acta Crystallogr., C40 (3): 570, 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, doi:10.2113/gscanmin.45.5.1275
  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
  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
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