Aluminium sulfide

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Aluminium sulfide
Names
Other names
Aluminium sulfide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.013.736 Edit this at Wikidata
EC Number
  • 215-109-0
UNII
  • InChI=1S/2Al.3S/q2*+3;3*-2 checkY
    Key: COOGPNLGKIHLSK-UHFFFAOYSA-N checkY
  • InChI=1/2Al.3S/q2*+3;3*-2
    Key: COOGPNLGKIHLSK-UHFFFAOYAY
  • [Al+3].[Al+3].[S-2].[S-2].[S-2]
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
105.1 J/mol K
116.9 J/mol K
-724 kJ/mol
Hazards
GHS labelling:
GHS02: FlammableGHS07: Exclamation mark
Danger
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 0: Will not burn. E.g. waterInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
4
0
2
W
Safety data sheet (SDS) [1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

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).

Crystal structure[edit]

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.

Preparation[edit]

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.

References[edit]

  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. (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.
  4. ^ 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.
  5. ^ 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.
  6. ^ McPherson, William; Henderson, William E. (1913). A course in general chemistry. Boston: Ginn and Company. p. 445.
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