Lithium fluoride

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Lithium fluoride
Lithium fluoride boule
Lithium fluoride
__ Li+     __ F−

__ Li+     __ F−
Names
IUPAC name
Lithium fluoride
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
 100.029.229 Edit this at Wikidata
EC Number
  • 232-152-0
RTECS number
  • OJ6125000
UNII
  • InChI=1S/FH.Li/h1H;/q;+1/p-1 checkY
    Key: PQXKHYXIUOZZFA-UHFFFAOYSA-M checkY
  • InChI=1/FH.Li/h1H;/q;+1/p-1
    Key: PQXKHYXIUOZZFA-REWHXWOFAG
  • [Li+].[F-]
Properties
LiF
Molar mass 25.939(2) g/mol
Appearance White powder or colorless
hygroscopic
crystals
Density 2.635 g/cm3
Melting point 845 °C (1,553 °F; 1,118 K)
Boiling point 1,676 °C (3,049 °F; 1,949 K)
0.127 g/(100 mL) (18 °C)
0.134 g/(100 mL) (25 °C)
1.84×10−3[1]
Solubility soluble in HF
insoluble in alcohol
−10.1·10−6 cm3/mol
1.3915
Structure
Face-centered cubic
a = 403.51 pm
Linear
Thermochemistry
1.507 J/(g·K)
35.73 J/(mol·K)
Std enthalpy of
formation
(ΔfH⦵298)
 -616 kJ/mol
Hazards
GHS labelling:
GHS06: Toxic
Danger
H301, H315, H319, H335[2]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
0
0
Lethal dose or concentration (LD, LC):
143 mg/kg (oral, rat)[3]
Related compounds
Other anions
 Lithium chloride
Lithium bromide
Lithium iodide
Lithium astatide
Other cations
 Sodium fluoride
Potassium fluoride
Rubidium fluoride
Caesium fluoride
Francium fluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Lithium fluoride is an inorganic compound with the chemical formula LiF. It is a colorless solid that transitions to white with decreasing crystal size. Its structure is analogous to that of

BeO
.

Manufacturing

LiF is prepared from lithium hydroxide or lithium carbonate with hydrogen fluoride.[5]

Applications

Precursor to lithium hexafluorophosphate for batteries

Lithium fluoride is reacted with

lithium ion battery electrolyte
.

The lithium fluoride alone does not absorb hydrogen fluoride to form a bifluoride salt.[6]

In molten salts

Fluorine is produced by the electrolysis of molten potassium bifluoride. This electrolysis proceeds more efficiently when the electrolyte contains a few percent of LiF, possibly because it facilitates formation of an Li-C-F interface on the carbon electrodes.[4] A useful molten salt, FLiNaK, consists of a mixture of LiF, together with sodium fluoride and potassium fluoride. The primary coolant for the Molten-Salt Reactor Experiment was FLiBe; 2LiF·BeF2 (66 mol% of LiF, 33 mol% of BeF2).

Optics

Because of the large

transparent to short wavelength ultraviolet radiation, more so than any other material. LiF is therefore used in specialized optics for the vacuum ultraviolet spectrum.[7] (See also magnesium fluoride.) Lithium fluoride is used also as a diffracting
crystal in X-ray spectrometry.

Radiation detectors

It is also used as a means to record

6
3Li
 (n,alpha) nuclear reaction) in thermoluminescent dosimeters. 6LiF nanopowder enriched to 96% has been used as the neutron reactive backfill material for microstructured semiconductor neutron detectors (MSND).[8]

Nuclear reactors

Lithium fluoride (highly enriched in the common isotope lithium-7) forms the basic constituent of the preferred fluoride salt mixture used in

liquid-fluoride nuclear reactors. Typically lithium fluoride is mixed with beryllium fluoride to form a base solvent (FLiBe), into which fluorides of uranium and thorium are introduced. Lithium fluoride is exceptionally chemically stable and LiF/BeF2 mixtures (FLiBe) have low melting points (360 to 459 °C or 680 to 858 °F) and the best neutronic properties of fluoride salt combinations appropriate for reactor use. MSRE
used two different mixtures in the two cooling circuits.

Cathode for PLED and OLEDs

Lithium fluoride is widely used in

dielectric constant (or relative permittivity, ε) of LiF is 9.0.[9]

Natural occurrence

Naturally occurring lithium fluoride is known as the extremely rare mineral griceite.[10]

References

  1. ISBN 978-1138561632
    .
  2. ^ "Lithium fluoride - Product Specification Sheet". Sigma-Aldrich. Merck KGaA. Retrieved 1 Sep 2019.
  3. NLM. Archived
    from the original on 12 August 2014. Retrieved 10 Aug 2014.
  4. ^
    ISBN 9783527303854
    .
  5. S2CID 19657691
    .
  6. ISBN 978-3527306732
    .
  7. ^ "Lithium Fluoride (LiF) Optical Material". Crystran 19. 2012.
  8. hdl:2097/16983
    .
  9. doi:10.1103/PhysRevB.2.5068
    .
  10. ^ "Griceite mineral information and data". Mindat.org. Archived from the original on 7 March 2014. Retrieved 22 Jan 2014.
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