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Tin(II) selenide

Tin selenide
Names
Other names
Tin(II) selenide
Identifiers
3D model (JSmol)
ECHA InfoCard 100.013.871
EC Number 215-257-6
PubChem CID
Properties
SnSe
Molar mass 197.67 g/mol
Appearance steel gray odorless powder
Density 6.179 g/cm3
Melting point 861 °C (1,582 °F; 1,134 K)
negligible
Band gap 0.9 eV (indirect), 1.3 eV (direct)
Structure
Orthorhombic, oP8
Pnma, No. 62
Thermochemistry
-88.7 kJ/mol
Hazards
Safety data sheet https://www.ltschem.com/msds/SnSe.pdf
Toxic (T)
Dangerous for the environment (N)
R-phrases (outdated) R23/25, R33, R50/53
S-phrases (outdated) (S1/2), S20/21, S28, S45, S60, S61
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
Related compounds
Other anions
Tin(II) oxide
Tin(II) sulfide
Tin telluride
Other cations
Carbon monoselenide
Silicon monoselenide
Germanium selenide
Lead selenide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YesYN ?)
Infobox references

Tin selenide, also known as stannous selenide, is an inorganic compound with the formula (SnSe), where Tin has a +2 oxidation state. Tin(II) selenide is a narrow band-gap (IV-VI) semiconductor and has received considerable interest for applications including low-cost photovoltaics and memory-switching devices. Tin(II) selenide is a typical layered metal chalcogenide; that is, it includes a Group 16 anion (Se2−) and an electropositive element (Sn2+), and it is arranged in a layered structure.

Tin(II) selenide exhibits low thermal conductivity as well as reasonable electrical conductivity, creating the possibility of it being used in thermoelectric materials. In 2014, a team at Northwestern University has established the world record performance for thermoelectric material efficiency.

Tin(II) selenide (SnSe) has stiff bonds and distorted lattice, crystallizing in the orthorhombic GeSe (germanium selenide) structure. To be isomorphous, two substances must have the same chemical formulation, and they must contain atoms with corresponding chemical properties and with similar atomic radii. Tin(II) selenide exists in a doubled layered structure that derives from a distorted rock-salt structure. Within these double layers, each tin atom is covalently bonded to three neighboring selenide (Se) atoms, and each selenide atom is covalently bonded to three neighboring tin atoms. The double layers are then held together primarily by van der Waals forces.

Tin(II) selenide’s layered structure bestows both anharmonic and anisotropic bonding to the compound.

At pressures above 58 GPa, SnSe acts as a superconductor; this change of conductivity is likely due to a change in the structure to that of a CsCl structure.

Tin(II) selenide can be formed by reacting the elements tin and selenium above 350 °C.


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