Potassium fluorosilicate

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Potassium fluorosilicate
Names
Preferred IUPAC name
Potassium fluorosilicate
Other names
Potassium hexafluorosilicate(IV)
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.037.163 Edit this at Wikidata
EC Number
RTECS number
  • VV8400000
UNII
UN number 2655
  • InChI=1S/F6Si.2K/c1-7(2,3,4,5)6;;/q-2;2*+1
    Key: UUHPPUWEDCVPCO-UHFFFAOYSA-N
  • F[Si-2](F)(F)(F)(F)F.[K+].[K+]
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 labelling:
GHS06: Toxic
Danger
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[edit]

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[edit]

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[edit]

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

Red phosphor[edit]

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[edit]

References[edit]

  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, 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. ^ 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