Gallium(III) sulfide

Gallium(III) sulfide, Ga2S3, is a compound of sulfur and gallium, that is a semiconductor that has applications in electronics and photonics.

Gallium(III) sulfide
Names
Other names
gallium sesquisulfide
Identifiers
3D model (JSmol)
ECHA InfoCard 100.031.526
EC Number
  • 234-688-0
Properties
Ga2S3
Molar mass 235.644 g/mol
Appearance yellow (α-)
Density 3.77 g/cm3 [1]
Melting point 1,090 °C (1,990 °F; 1,360 K)[1]
−-80·10−6 cm3/mol
Related compounds
Related compounds
 Gallium(II) sulfide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Structure

There are four polymorphs, α (hexagonal), α' (monoclinic), β(hexagonal) and γ(cubic). The alpha form is yellow. The crystal structures are related to those of ZnS with gallium in tetrahedral positions.[2][3][4] The alpha and beta forms are isostructural with their aluminium analogues.[5] The similarity in crystal form of gamma- with sphalerite (zinc blende), ZnS is believed to explain the enrichment of gallium in sphalerite ores.[5]

Preparation and chemical properties

Ga2S3 can prepared by reacting the elements at high temperature or as a white solid by heating Ga in a stream of H2S at high temperature (950 °C).[3]

It may also prepared by a solid state reaction of GaCl3 and Na2S.[5]

The method of production can determine the polymorphic form produced, the reaction of Ga(OH)3 with H2S at different temperatures is reported to produce a different polymorph depending on the temperature, α- 1020 K, β- 820 K and γ- above 873 K [6]

Ga2S3 disproportionates at high temperature forming the non-stoichiometric sulfide, Ga4Sx (4.8 < x < 5.2)[5] Ga2S3 dissolves in aqueous acids and decomposes slowly in moist air forming H2S.[3]

Ga2S3 dissolves in aqueous solutions of potassium sulfide, K2S to form K8Ga4S10 containing the (Ga4S10)8− anion which has an adamantane, molecular P4O10 structure.[5]

Ternary sulfides MIGaS2, MIIGa2S4 and MIIIGaS3 respectively have been of interest due to their unusual electrical properties and some of these can be prepared by reactions of Ga2S3 with metal sulfides e.g. CdGa2S4:-[5]

Ga2S3 + CdS → CdGa2S4

Although by itself Ga2S3 is not a glass former it can be reacted with rare earth sulfides to form glasses e.g. the reaction with lanthanum sulfide, La2S3, forms gallium lanthanum sulfide glass which has interesting optical properties and is a semiconductor.[7]

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References
  1. Handbook of Inorganic Compounds, Dale L. Perry, Taylor & Francis, 2011, ISBN 978-1-4398-1461-1
  2. Pardo, M.P.; Guittard, M.; Chilouet, A.; Tomas, A. (1993). "Diagramme de phases gallium-soufre et études structurales des phases solides". Journal of Solid State Chemistry. 102 (2): 423–433. doi:10.1006/jssc.1993.1054. ISSN 0022-4596.
  3. The Chemistry of Aluminium, Gallium, Indium and Thallium, Anthony John Downs, 1993, ISBN 075140103X , ISBN 978-0751401035
  4. Peter Atkins; T.L. Overton; J.P. Rourke; M.T. Weller; F.A. Armstrong (2010). Inorganic Chemistry (Fifth ed.). New York: W. H. Freeman and Company. p. 346. ISBN 978-1429218207.
  5. Barron, Andrew R.; MacInnes, Andrew N. (1994). "Gallium: Inorganic chemistry". In King, R. Bruce (ed.). Encyclopedia of Inorganic Chemistry. John Wiley and Sons. pp. 100–110. ISBN 0-471-93620-0.
  6. Semiconductors: Data Handbook 3d Ed., Otfried Madelung, Springer, 2004, ISBN 978-3540404880
  7. Semiconducting Chalcogenide Glass III: Applications of Chalcogenide Glasses, Robert Fairman, Boris Ushkov, Elsevier, 2004, (ebook), ISBN 9780080541068
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