Aluminium sulfide

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Aluminium sulfide
Sulfid hlinitý.PNG
CAS number 1302-81-4 N
PubChem 16684788
ChemSpider 140154 YesY
Jmol-3D images Image 1
Molecular formula Al2S3
Molar mass 150.158 g/mol
Appearance gray solid
Density 2.32 g/cm3
Melting point 1100 °C
Boiling point 1500 °C (sublimes)
Solubility in water decomposes
Solubility in other solvents none
EU classification not listed
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 4: Very short exposure could cause death or major residual injury. E.g., VX gas Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazards (white): no codeNFPA 704 four-colored diamond
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Aluminium sulfide or aluminium sulphide is a chemical compound with the formula Al2S3. This colorless species has an interesting structural chemistry, existing in several forms. The material is sensitive to moisture, hydrolyzing to hydrated aluminium oxides/hydroxides.1 This can begin when the sulfide is exposed to the atmosphere. The hydrolysis reaction generates gaseous hydrogen sulfide (H2S).

Crystal structure

More than six crystalline forms of aluminium sulfide are known and only some are listed below. Most of them have rather similar, wurtzite-like structures, and differ by the arrangement of lattice vacancies, which form ordered or disordered sublattices.23

Form Symmetry Space
a (A) c (A) ρ (g/cm3)
α Hexagonal 6.423 17.83 2.32
β Hexagonal P63mc 3.579 5.829 2.495
γ Trigonal 6.47 17.26 2.36
δ Tetragonal I41/amd 7.026 29.819 2.71

The β and γ phases are obtained by annealing the most stable α-Al2S3 phase at several hundred degrees Celsius.4 Compressing aluminium sulfide to 2–65 kbar results in the δ phase where vacancies are arranged in a superlattice of tetragonal symmetry.5

Unlike Al2O3, in which the Al(III) centers occupy octahedral holes, the more expanded framework of Al2S3 stabilizes the Al(III) centers into one third of the tetrahedral holes of a hexagonally close-packed arrangement of the sulfide anions. At higher temperature, the Al(III) centers become randomized to give a "defect wurtzite" structure. And at still higher temperatures stabilize the γ-Al2S3 forms, with a structure akin to γ-Al2O3.

Molecular derivatives of Al2S3 are not known. Mixed Al-S-Cl compounds are however known. Al2Se3 and Al2Te3 are also known.


Aluminium sulfide is readily prepared by ignition of the elements6

2 Al + 3 S → Al2S3

This reaction is extremely exothermic and it is not necessary or desirable to heat the whole mass of the sulfur-aluminium mixture; (except possibly for very small amounts of reactants). The product will be created in a fused form; it reaches a temperature greater than 1100 °C and may melt its way through steel. The cooled product is very hard.


  1. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  2. ^ Hans Landolt; D. Bimberg, Richard Börnstein; Richard Börnstein (1982). Halbleiter. Springer. pp. 12–. ISBN 978-3-540-13507-4. Retrieved 23 September 2011. 
  3. ^ Flahaut J. Ann. Chim. (Paris) 7 (1952) 632–696
  4. ^ Krebs, Bernt; Schiemann, Anke; läGe, Mechtild (1993). "Synthese und Kristallstruktur einer Neuen hexagonalen Modifikation von Al2S3 mit fünffach koordiniertem Aluminium". Zeitschrift für anorganische und allgemeine Chemie 619 (6): 983. doi:10.1002/zaac.19936190604. 
  5. ^ Donohue, P (1970). "High-pressure spinel type Al2S3 and MnAl2S4". Journal of Solid State Chemistry 2: 6. Bibcode:1970JSSCh...2....6D. doi:10.1016/0022-4596(70)90024-1. 
  6. ^ McPherson, William (1913). Laboratory manual. Boston: Ginn and Company. p. 445. 

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