Aluminium sulfide

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Aluminium sulfide
Sulfid hlinitý.PNG
Identifiers
CAS number 1302-81-4 N
PubChem 16684788
ChemSpider 140154 YesY
Jmol-3D images Image 1
Properties
Molecular 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
Specific
heat capacity
C
105.1 J/mol K
Std molar
entropy
So298
116.9 J/mol K
Std enthalpy of
formation
ΔfHo298
-724 kJ/mol
Hazards
MSDS MSDS
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[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 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.

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. 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.