Mercury selenide is a chemical compound of mercury

Mercury (element)

Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...

 and selenium

Selenium

Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...

. It is a grey-black crystal

Crystal

A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...

line solid semi-metal with a sphalerite structure. The lattice constant

Lattice constant

The lattice constant [or lattice parameter] refers to the constant distance between unit cells in a crystal lattice. Lattices in three dimensions generally have three lattice constants, referred to as a, b, and c. However, in the special case of cubic crystal structures, all of the constants are...

 is 0.608 nm.

Mercury selenide can also refer to the following chemical compounds: HgSe₂ and HgSe₈. HgSe is strictly mercury(II) selenide.

HgSe occurs naturally as the mineral Tiemannite

Tiemannite

Tiemannite is a mineral, mercury selenide, formula HgSe. It occurs in hydrothermal veins associated with other selenides, or other mercury minerals such as cinnabar, and often with calcite. Discovered in 1855 in Germany, it is named after C. W...

.

Along with other II-VI compounds, colloidal nanocrystals of HgSe can be formed.

Applications

• Selenium is used in filters in some steel plants to remove mercury from exhaust gases. The solid product formed is HgSe.
• HgSe can be used as an ohmic contact to wide-gap II-VI semiconductors such as zinc selenide or zinc oxide
  Zinc oxide
  Zinc oxide is an inorganic compound with the formula ZnO. It is a white powder that is insoluble in water. The powder is widely used as an additive into numerous materials and products including plastics, ceramics, glass, cement, rubber , lubricants, paints, ointments, adhesives, sealants,...
  
  .

Toxicity

HgSe is non-toxic so long as it is not ingested due to its insolubility. Toxic hydrogen selenide

Hydrogen selenide

Hydrogen selenide is the inorganic compound with the formula H2Se. It is the simplest and virtually the only hydride of selenium. H2Se is a colorless, flammable gas under standard conditions. It is the most toxic selenium compound with an exposure limit: 0.05 ppm over an 8 hour period...

 fumes can be evolved on exposure to acids. HgSe is a relatively stable compound which might mean that it is less toxic than elemental mercury or many organometallic mercury compounds. Selenium's ability to complex with mercury has been proposed as a reason for the lack of mercury toxicity in deep sea fish despite high mercury levels.

See also

• Mercury sulfide
  Mercury sulfide
  Mercury sulfide, mercuric sulfide, or mercury sulfide is a chemical compound composed of the chemical elements mercury and sulfur. It is represented by the chemical formula HgS...
  
  
• Mercury telluride
• Cadmium selenide
  Cadmium selenide
  Cadmium selenide is a solid, binary compound of cadmium and selenium. Common names for this compound are cadmium selenide, cadmium selenide, and cadmoselite ....
  
  
• Zinc selenide
  Zinc selenide
  Zinc selenide , is a light yellow binary solid compound. It is an intrinsic semiconductor with a band gap of about 2.70 eV at 25 °C. ZnSe rarely occurs in nature...
  
  

External links

• http://ctdp.ensmp.fr/species/Tiemannite.html
• List of related Hg chalcogenides