Aluminium sulfide

Aluminium sulfide
Names
	Other names Aluminium sulfide
Identifiers
CAS Number	1302-81-4 [ECHA];
3D model (JSmol)	Interactive image;
ChemSpider	140154 ;
ECHA InfoCard	100.013.736
EC Number	215-109-0;
PubChem CID	16684788;
UNII	04PI6P2Z18 ;
CompTox Dashboard (EPA)	DTXSID80893235 ;
	InChI InChI=1S/2Al.3S/q2+3;3-2 Key: COOGPNLGKIHLSK-UHFFFAOYSA-N ; InChI=1/2Al.3S/q2+3;3-2 Key: COOGPNLGKIHLSK-UHFFFAOYAY;
	SMILES [Al+3].[Al+3].[S-2].[S-2].[S-2];
Properties
Chemical formula	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
Solubility in water	decomposes
Solubility	insoluble in acetone
Structure
Crystal 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
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
NFPA 704 (fire diamond)	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). verify (what is ?) Infobox references

Aluminium sulfide is a chemical compound with the formula Al₂ S₃. 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.^[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

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 1,100 °C and may melt its way through steel. The cooled product is very hard.

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. 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.

[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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