Tungsten disilicide

Tungsten silicide (WSi2) is an inorganic compound, a silicide of tungsten. It is an electrically conductive ceramic material.

Tungsten disilicide[1]
Names
IUPAC name
Tungsten disilicide
Identifiers
3D model (JSmol)
ECHA InfoCard 100.031.723
Properties
WSi2
Molar mass 240.011 g/mol
Appearance blue-gray tetragonal crystals
Density 9.3 g/cm3
Melting point 2,160 °C (3,920 °F; 2,430 K)
insoluble
Hazards
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
0
1
0
Flash point Non-flammable
Related compounds
Other anions
Tungsten carbide
Tungsten nitride
Other cations
Molybdenum disilicide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

ChemistryEdit

Tungsten silicide can react violently with substances such as strong acids, fluorine, oxidizers, and interhalogens.

ApplicationsEdit

It is used in microelectronics as a contact material, with resistivity 60–80 μΩ cm; it forms at 1000 °C. It is often used as a shunt over polysilicon lines to increase their conductivity and increase signal speed. Tungsten silicide layers can be prepared by chemical vapor deposition, e.g. using monosilane or dichlorosilane with tungsten hexafluoride as source gases. The deposited film is non-stoichiometric, and requires annealing to convert to more conductive stoichiometric form. Tungsten silicide is a replacement for earlier tungsten films.[2] Tungsten silicide is also used as a barrier layer between silicon and other metals, e.g. tungsten.

Tungsten silicide is also of value towards use in microelectromechanical systems, where it is mostly applied as thin films for fabrication of microscale circuits. For such purposes, films of tungsten silicide can be plasma-etched using e.g. nitrogen trifluoride gas.

WSi2 performs well in applications as oxidation-resistant coatings. In particular, in similarity to Molybdenum disilicide, MoSi2, the high emissivity of tungsten disilicide makes this material attractive for high temperature radiative cooling, with implications in heat shields.[3]

ReferencesEdit

  1. ^ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 4–91, ISBN 0-8493-0594-2
  2. ^ "Archived copy". Archived from the original on 2001-09-07. Retrieved 2007-08-19.CS1 maint: archived copy as title (link)
  3. ^ High emissivity coatings on fibrous ceramics for reusable space systems Corrosion Science 2019