Chalcogenide

Chalcogenides are chemical compounds of one or more chalcogen elements (oxygen, sulfur, selenium and tellurium) as a formal anion with metals or more electropositive elements ( arsenic, germanium, phosphorus, antimony, lead, boron, aluminum, gallium, indium, titanium, sodium) as a formal cations.

Subdivision

Chalcogenides are therefore divided into oxides, sulfides, selenides and tellurides, and form, depending on the binding partner gaseous (such as carbon dioxide ) or generally solids. As solids they can form compounds with ionic or covalent character depends on the electronegativity difference. The solids usually occurs in crystalline form, but they can also be prepared as amorphous glassy materials. Formally, they can be regarded as salts of the respective Chalkogenwasserstoffsäure (water, hydrogen sulfide, hydrogen selenide and telluride ).

Importance

Rather ionic chalcogenides such as iron sulfide or cadmium sulfide occur as sulfidic ores and minerals and are used for example as pigments ( HgS, cinnabar, CdS, cadmium yellow, CdSe, cadmium red, ZnS, zinc sulphide).

Technical significance of the rather glassy chalcogenides as

  • Optical glasses for the infrared region: The lenses are transparent in the spectral range of 1-14 micron wavelength of light. ( GE33 AS12 SE55, SE32 TE25 GE30 AS13, AS40 Ge10 SE50, SE60 GE28 Sb12, AS40 SE60 )
  • Coating rewritable optical storage media: in the form of alloys of chalcogenides it represents the active material at CD -RWs and DVD-RAMs dar. This exploits that the optical properties of the two phases ( amorphous, crystalline ) are different and that stable as at temperature (laser ) can switch back and forth the material between the two phases (see phase change technology ).
  • The resistive element in electronic storage phase -change random access memory: Also in the form of alloys of chalcogenides it is the active material in these novel non- volatile memories dar. This exploits that the electrical properties ( electrical resistance) of the two phases (amorphous, crystalline) and that differ by stable temperature ( current pulse ) the material can switch back and forth between the two phases.
  • Photoresist in photolithography
  • Substance Group
  • Chalcogenide
Abiogenesis Aluminium Sinople CD-RW Non-volatile random-access memory
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