Tin telluride is a compound of

tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, ...

and

tellurium Tellurium is a chemical element with the symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally fo ...

(SnTe); is a IV-VI narrow band gap semiconductor and has direct

band gap In solid-state physics, a band gap, also called an energy gap, is an energy range in a solid where no electronic states can exist. In graphs of the electronic band structure of solids, the band gap generally refers to the energy difference ( ...

of 0.18 eV. It is often alloyed with lead to make lead tin telluride, which is used as an

infrared detector An infrared detector is a detector that reacts to infrared (IR) radiation. The two main types of detectors are thermal and photonic (photodetectors). The thermal effects of the incident IR radiation can be followed through many temperature depen ...

material. Tin telluride normally forms p-type semiconductor (

Extrinsic semiconductor An extrinsic semiconductor is one that has been '' doped''; during manufacture of the semiconductor crystal a trace element or chemical called a doping agent has been incorporated chemically into the crystal, for the purpose of giving it differen ...

) due to tin vacancies and is a low temperature superconductor. SnTe exists in three crystal phases. At Low temperatures, where the concentration of hole carriers is less than 1.5x10²⁰ cm⁻³ , Tin Telluride exists in rhombohedral phase also known as α-SnTe. At room temperature and atmospheric pressure, Tin Telluride exists in NaCl-like cubic crystal phase, known as β-SnTe. While at 18 kbar pressure, β-SnTe transforms to γ-SnTe, orthorhombic phase,

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it ...

Pnma. This phase change is characterized by 11 percent increase in density and 360 percent increase in resistance for γ-SnTe. Tin telluride is a thermoelectric material. Theoretical studies imply that the n-type performance may be particularly good.

Thermal properties

Standard enthalpy of formation In chemistry and thermodynamics, the standard enthalpy of formation or standard heat of formation of a compound is the change of enthalpy during the formation of 1 mole of the substance from its constituent elements in their reference state, w ...

: - 14.6 ± 0.3 kcal/mole at 298 K * Standard

Enthalpy of sublimation In thermodynamics, the enthalpy of sublimation, or heat of sublimation, is the heat required to sublimate (change from solid to gas) one mole of a substance at a given combination of temperature and pressure, usually standard temperature and p ...

: 52.1 ± 1.4 kcal/mole at 298 K *

Heat capacity Heat capacity or thermal capacity is a physical property of matter, defined as the amount of heat to be supplied to an object to produce a unit change in its temperature. The SI unit of heat capacity is joule per kelvin (J/K). Heat capacity ...

: 12.1 + 2.1 x 10⁻³ T cal/deg *

Bond-dissociation energy The bond-dissociation energy (BDE, ''D''0, or ''DH°'') is one measure of the strength of a chemical bond . It can be defined as the standard enthalpy change when is cleaved by homolysis to give fragments A and B, which are usually radical ...

for the reaction SnTe(g)-> Sn(g)+ Te(g) : 80.6 ± 1.5 kcal/mole at 298 K *

Entropy Entropy is a scientific concept, as well as a measurable physical property, that is most commonly associated with a state of disorder, randomness, or uncertainty. The term and the concept are used in diverse fields, from classical thermodyna ...

: 24.2±0.1 cal/mole.deg * Enthalpy of Dimerization for the reaction Sn₂Te₂->2SnTe(g) :46.9 ± 6.0 kcal/mole

Applications

Generally Pb is alloyed with SnTe in order to access interesting optical and electronic properties, In addition, as a result of

Quantum confinement A potential well is the region surrounding a local minimum of potential energy. Energy captured in a potential well is unable to convert to another type of energy (kinetic energy in the case of a gravitational potential well) because it is captu ...

, the band gap of the SnTe increases beyond the bulk band gap, covering the mid-IR wavelength range. The alloyed material has been used in mid- IR

photodetector Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation. There is a wide variety of photodetectors which may be classified by mechanism of detection, such as photoelectric or photochemical effects, or by ...

s and

thermoelectric generator A thermoelectric generator (TEG), also called a Seebeck generator, is a solid state device that converts heat flux ( temperature differences) directly into electrical energy through a phenomenon called the ''Seebeck effect'' (a form of thermoele ...

.Das, V. D.; Bahulayan, C., Variation of electrical transport properties and thermoelectric figure of merit with thickness in 1% excess Te-doped Pb 0.2 Sn 0.8 Te thin films. Semiconductor Science and Technology 1995, 10 (12), 1638.

References

External links

Berlin thermophysical properties database

Landolt-Börnstein Substance/SnTe index

Reflectivity of Tin Telluride in the Infrared
Tellurides Tin(II) compounds IV-VI semiconductors Rock salt crystal structure {{material-stub