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Selenium ( Se )

Material Information

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Foil Lump Powder Sputtering Target
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General Description:  

Selenium was discovered in 1817 by J.J. Berzelius in Stockholm, Sweden.

Selenium exists in several allotropic forms; red selenium is monoclinic and contains Se8 rings. It has a melting point of 180C and a relative density of 4.45. The grey (metallic) form of selenium is formed when other varieties are heated to 200C; this has a melting point of 220C and a relative density of 4.80. Selenium is widely distributed, mainly as the selenides of heavy metals, but only has an abundance of 0.05 ppm in the earth's crust. The metal burns in air and is unaffected by water. It is soluble in alkalis and concentrated nitric acid.

The electrical properties of selenium are of particular interest as it is both photovoltaic (i.e. it becomes an electrical conductor when exposed to light or ultra violet radiation) and photoconductive (i.e. the electrical conductivity increases with increasing illumination). These properties mean that selenium has applications in the electronics industry (e.g. in the manufacture of photoelectric cells and solar cells). Selenium is used in the ceramics and glass industries (in the latter the element being used as a decoloriser and also in the manufacture of red glasses and enamels). Selenium is an important trace element for humans, the average body containing approximately 14 mg.

   

Atomic Properties

Atomic number 34
Atomic radius - Goldschmidt ( nm ) 0.116
Atomic weight ( amu ) 78.96
Crystal structure Hexagonal
Electronic structure Ar 3d1O 4s2 4p4
Ionization potential No. eV
1 9.75
2 21.2
3 30.8
4 42.9
5 68.3
6 81.7
Natural isotope distribution Mass No. %
74 0.9
76 9.0
77 7.6
78 23.5
80 49.8
82 9.2
Photo-electric work function ( eV ) 5.9
Thermal neutron absorption cross-section ( Barns ) 12.2
Valences shown -2, 4, 6

Electrical Properties

Electrical resistivity @20C ( µOhmcm ) 12

Mechanical Properties

Material condition Polycrystalline
Bulk modulus ( GPa ) 8.3
Hardness - Mohs 2.0
Poisson's ratio 0.447
Tensile modulus ( GPa ) 58

Physical Properties

Boiling point ( C ) 685
Density @20C ( g cm-3 ) 4.79
Melting point ( C ) 217

Thermal Properties

Coefficient of thermal expansion @0-100C ( x10-6 K-1 ) 37
Latent heat of evaporation ( J g-1 ) 333
Latent heat of fusion ( J g-1 ) 69
Specific heat @25C ( J K-1 kg-1 ) 321
Thermal conductivity @0-100C ( W m-1 K-1 ) 0.5
All information and technical data are given as a guide only. Although every effort has been made to ensure that the information is correct, no warranty is given as to its completeness or accuracy.

Buy Selenium on-line

We stock and supply the following standard forms:
Foil Lump Powder Sputtering Target
Foil Lump Powder Sputtering Target

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