View source for Chemistry:Aluminium sulfide

{{chembox 
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 477000841
| Name = Aluminium sulfide
| OtherNames = Aluminium sulfide
| ImageFile = Sulfid hlinitý.PNG
|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 140154
| EINECS = 215-109-0
| InChI = 1/2Al.3S/q2*+3;3*-2
| InChIKey = COOGPNLGKIHLSK-UHFFFAOYAY
| SMILES = [Al+3].[Al+3].[S-2].[S-2].[S-2]
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/2Al.3S/q2*+3;3*-2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = COOGPNLGKIHLSK-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|ECHA}}
| CASNo = 1302-81-4
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 04PI6P2Z18
| PubChem = 16684788
 }}
|Section2={{Chembox Properties
| Formula = Al<sub>2</sub>S<sub>3</sub>
| MolarMass = 150.158 g/mol
| Appearance = gray solid
| Density = 2.02 g/cm<sup>3</sup>
| Solubility = decomposes
| SolubleOther = insoluble in [[Chemistry:Acetone|acetone]]
| MeltingPtC = 1100
| BoilingPtC = 1500
| BoilingPt_notes = sublimes
 }}
|Section3={{Chembox Structure
| CrystalStruct = trigonal
}}
|Section4={{Chembox Thermochemistry
| DeltaHf = -724 kJ/mol
| Entropy = 116.9 J/mol K
| HeatCapacity = 105.1 J/mol K
}}
|Section7={{Chembox Hazards
| GHSPictograms = {{GHS02}}{{GHS07}}
| GHSSignalWord = Danger
| HPhrases = 
| PPhrases = 
| NFPA-H = 4
| NFPA-R = 2
| NFPA-F = 0
| NFPA-S = W
| ExternalSDS = [https://www.ltschem.com/msds/Al2S3.pdf]
 }}
}}

'''Aluminium sulfide''' is a [[Chemistry:Chemical compound|chemical compound]] with the formula [[Chemistry:Aluminium|Al<sub>2</sub>]][[Chemistry:Sulfur|S<sub>3</sub>]]. This colorless species has an interesting structural chemistry, existing in several forms. The material is sensitive to moisture, hydrolyzing to hydrated aluminum oxides/hydroxides.<ref>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. {{ISBN|0-12-352651-5}}.</ref> This can begin when the sulfide is exposed to the atmosphere. The hydrolysis reaction generates gaseous [[Chemistry:Hydrogen sulfide|hydrogen sulfide]] (H<sub>2</sub>S).

==Crystal structure==
More than six crystalline forms of aluminium sulfide are known and only some are listed below. Most of them have rather similar, [[Physics:Wurtzite crystal structure|wurtzite]]-like structures, and differ by the arrangement of lattice vacancies, which form ordered or disordered sublattices.<ref>{{cite book|author1=Hans Landolt|author2=D. Bimberg, Richard Börnstein|author3=Richard Börnstein|title=Halbleiter|url=https://books.google.com/books?id=suSjL5FLV30C&pg=PA12|access-date=23 September 2011|year=1982|publisher=Springer|isbn=978-3-540-13507-4|pages=12–}}</ref><ref>Flahaut J. Ann. Chim. (Paris) 7 (1952) 632–696</ref>

{|class="wikitable"
!Form !!Symmetry!!Space<br>group!!a (A)!!c (A)!!ρ (g/cm<sup>3</sup>)
|-
| α||Hexagonal|| P6<sub>1</sub> || 6.423 ||17.83||2.32
|-
|β || Hexagonal||P6<sub>3</sub>mc||3.579 ||5.829 ||2.495
|-
| γ|| Trigonal|| ||6.47||17.26 ||2.36
|-
|δ ||Tetragonal|| I4<sub>1</sub>/amd ||7.026||29.819|| 2.71
|}

The β and γ phases are obtained by annealing the most stable α-Al<sub>2</sub>S<sub>3</sub> phase at several hundred degrees Celsius.<ref>{{cite journal|doi=10.1002/zaac.19936190604|title=Synthese und Kristallstruktur einer Neuen hexagonalen Modifikation von Al2S3 mit fünffach koordiniertem Aluminum|year=1993|last1=Krebs|first1=Bernt|last2=Schiemann|first2=Anke|last3=läGe|first3=Mechtild|journal=Zeitschrift für anorganische und allgemeine Chemie|volume=619|issue=6|pages=983}}</ref> Compressing aluminium sulfide to 2–65 [[Bar (unit)|bar]] results in the δ phase where vacancies are arranged in a superlattice of tetragonal symmetry.<ref>{{cite journal|doi=10.1016/0022-4596(70)90024-1|title=High-pressure spinel type Al2S3 and MnAl2S4|year=1970|last1=Donohue|first1=P|journal=Journal of Solid State Chemistry|volume=2|issue=1|pages=6–8 |bibcode = 1970JSSCh...2....6D }}</ref>

Unlike [[Chemistry:Aluminium oxide|Al<sub>2</sub>O<sub>3</sub>]], in which the Al(III) centers occupy octahedral holes, the more expanded framework of Al<sub>2</sub>S<sub>3</sub> 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 [[Physics:Wurtzite crystal structure|wurtzite]]" structure. And at still higher temperatures stabilize the γ-Al<sub>2</sub>S<sub>3</sub> forms, with a structure akin to γ-Al<sub>2</sub>O<sub>3</sub>.

Molecular derivatives of Al<sub>2</sub>S<sub>3</sub> are not known. Mixed Al-S-Cl compounds are however known. Al<sub>2</sub>Se<sub>3</sub> and Al<sub>2</sub>Te<sub>3</sub> are also known.

==Preparation==
Aluminium sulfide is readily prepared by ignition of the elements<ref>{{cite book|last=McPherson|first=William|title=Laboratory manual|year=1913|publisher=Ginn and Company|location=Boston|page=445|url=https://books.google.com/books?id=oaMe7OtctlIC&q=%22aluminium+sulfide%22}}</ref>

:2 Al + 3 S → Al<sub>2</sub>S<sub>3</sub>

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&nbsp;°C and may melt its way through steel. The cooled product is very hard.

==References==
{{Reflist}}
{{Sulfur compounds}}
{{Aluminium compounds}}
{{Sulfides}}

[[Category:Sesquisulfides]]
[[Category:Aluminium compounds]]

{{Sourceattribution|Aluminium sulfide}}