Aluminium sulfide
| Aluminium sulfide | |
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Other names
Aluminum sulfide |
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| Identifiers | |
| CAS number | 1302-81-4  |
| PubChem | 16684788 |
| ChemSpider | 140154 |
| Jmol-3D images | Image 1 |
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| Properties | |
| 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 |
| Hazards | |
| MSDS | MSDS |
| EU classification | not listed |
| NFPA 704 |
 0
4
2
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 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 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).
[edit] 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.[2][3]
| Form | Symmetry | Space group |
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.
[edit] Preparation
Aluminium sulfide is readily prepared by ignition of the elements
- 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.
[edit] References
- ^ 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. http://books.google.com/books?id=suSjL5FLV30C&pg=PA12. Retrieved 23 September 2011.
- ^ Flahaut J. Ann. Chim. (Paris) 7 (1952) 632–696
- ^ 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.
- ^ Donohue, P (1970). "High-pressure spinel type Al2S3 and MnAl2S4". Journal of Solid State Chemistry 2: 6. doi:10.1016/0022-4596(70)90024-1.
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