Tin(II) sulfide
Chemical compound
From Wikipedia, the free encyclopedia
Tin(II) sulfide is an inorganic compound with the chemical formula is SnS. A black or brown solid, it occurs as the rare mineral herzenbergite (α-SnS).It is insoluble in water but dissolves with degradation in concentrated hydrochloric acid. Tin(II) sulfide is insoluble in ammonium sulfide.
| Names | |
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| IUPAC name
Tin(II) sulfide | |
| Other names
Tin monosulfide Herzenbergite | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.013.863 |
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PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| SnS | |
| Molar mass | 150.775 g/mol |
| Appearance | dark brown solid |
| Density | 5.22 g/cm3 |
| Melting point | 882 °C (1,620 °F; 1,155 K) |
| Boiling point | about 1230 ˚C |
| Insoluble | |
| Structure | |
| GeS type (orthorhombic), oP8 | |
| Pnma, No. 62 | |
| asymmetric 3-fold (strongly distorted octahedral) | |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards |
Irritant |
| Related compounds | |
Other anions |
Tin(II) oxide Tin selenide Tin telluride |
Other cations |
Carbon monosulfide Silicon monosulfide Germanium monosulfide Lead(II) sulfide |
Related compounds |
Tin(IV) sulfide Tributyl tin sulfide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Synthesis
The preparation of tin(II) sulfide has been extensively investigated, and the direct reaction of the elements is inefficient.[3] Instead, molten potassium thiocyanate reliably reacts with stannic oxide to give SnS at 450 °C:[4]
- SnO2 + 2 KSCN → SnS + K2S + 2CO + N2
SnS also forms when aqueous solutions of tin(II) salts are treated with hydrogen sulfide.[5] This conversion is a step in qualitative inorganic analysis.
At cryogenic temperatures, stannous chloride dissolves in liquid hydrogen sulfide. It then decomposes to the sulfide, but only slowly.[6]
Structure
At temperatures above 905 K, SnS undergoes a second order phase transition to β-SnS (space group: Cmcm, No. 63).[7] A new polymorph of SnS exists based upon the cubic crystal system, known as π-SnS (space group: P213, No. 198).[8][9][10] Herzenbergite (α-SnS) can be exfoliated to form layered structure similar to that of black phosphorus, featuring 3-coordinate Sn and S centers.[5][7] Analogous to black phosphorus, tin(II) sulfide can be ultrasonically exfoliated in liquids to produce atomically thin semiconducting SnS sheets that have a wider optical band gap (>1.5 eV) compared to the bulk crystal.[11]
Photovoltaic applications
Tin(II) sulfide has been evaluated as a candidate for thin-film solar cells. Currently, both cadmium telluride and CIGS (copper indium gallium selenide) are used as p-type absorber layers, but they are formulated from toxic, scarce constituents.[12] Tin(II) sulfide, by contrast, is formed from cheap, earth-abundant elements, and is nontoxic. This material also has a high optical absorption coefficient, p-type conductivity, and a mid range direct band gap of 1.3-1.4 eV, required electronic properties for this type of absorber layer.[13] Based on the a detailed balance calculation using the material bandgap, the power conversion efficiency of a solar cell utilizing a tin(II) sulfide absorber layer could be as high as 32%, which is comparable to crystalline silicon.[14] Finally, Tin(II) sulfide is stable in both alkaline and acidic conditions.[15] All aforementioned characteristics suggest tin(II) sulfide as an interesting material to be used as a solar cell absorber layer.
Power conversion efficiencies for tin(II) sulfide thin films in photovoltaic cells are less than 5%.[16] Barriers for use include a low open circuit voltage and an inability to realize many of the above properties due to challenges in fabrication.[14]