Aluminium_sulfide
Aluminium sulfide
Chemical compound
Aluminium sulfide 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 aluminum oxides/hydroxides.[1] This can begin when the sulfide is exposed to the atmosphere. The hydrolysis reaction generates gaseous hydrogen sulfide (H2S).
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| Other names
Aluminium sulfide | |
| Identifiers | |
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| ECHA InfoCard | 100.013.736  |
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| Properties | |
| Al2S3 | |
| Molar mass | 150.158 g/mol |
| Appearance | gray solid |
| Density | 2.02 g/cm3 |
| Melting point | 1,100 °C (2,010 °F; 1,370 K) |
| Boiling point | 1,500 °C (2,730 °F; 1,770 K) sublimes |
| decomposes | |
| Solubility | insoluble in acetone |
| Structure | |
| trigonal | |
| Thermochemistry | |
Heat capacity (C) |
105.1 J/mol K |
Std molar entropy (S⦵298) |
116.9 J/mol K |
Std enthalpy of formation (ΔfH⦵298) |
-724 kJ/mol |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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.[2][3]
| Form | Symmetry | Space group | a (A) | c (A) | ρ (g/cm3) |
|---|---|---|---|---|---|
| α | Hexagonal | P61 | 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 bar 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 elements[6]
- 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.
- Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
- Hans Landolt; D. Bimberg, Richard Börnstein; Richard Börnstein (1982). Halbleiter. Springer. pp. 12–. ISBN 978-3-540-13507-4. Retrieved 23 September 2011.
- Flahaut, J. (1952). "Contribution à l'étude du sulfure d'aluminium et des thioaluminates" [Contribution to the study of aluminum sulfide and thioaluminates]. Annales de Chimie (Paris) (in French). 7: 632–696.
- Krebs, Bernt; Schiemann, Anke; läGe, Mechtild (1993). "Synthese und Kristallstruktur einer Neuen hexagonalen Modifikation von Al2S3 mit fünffach koordiniertem Aluminum". Zeitschrift für anorganische und allgemeine Chemie. 619 (6): 983. doi:10.1002/zaac.19936190604.
- Donohue, P (1970). "High-pressure spinel type Al2S3 and MnAl2S4". Journal of Solid State Chemistry. 2 (1): 6–8. Bibcode:1970JSSCh...2....6D. doi:10.1016/0022-4596(70)90024-1.
- McPherson, William; Henderson, William E. (1913). A course in general chemistry. Boston: Ginn and Company. p. 445.