Germanium selenide

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Germanium selenide
GeSeskylab.jpg
GeSe structure.jpg
Identifiers
CAS number 12065-10-0
PubChem 12049114
Properties
Molecular formula GeSe
Molar mass 151.57 g/mol
Appearance black
Density 5.56 g/cm3
Melting point 667 °C (decomposes)
Band gap 1.07 eV (indirect) [1]
Refractive index (nD) 2.5
Structure
Crystal structure Orthorhombic
Space group Pnma
Related compounds
Other anions Germanium sulfide, Germanium telluride
Related Lead selenide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Germanium selenide is a chemical compound with the formula GeSe. It exists as black crystalline powder having orthorhombic (distorted NaCl-type) crystal symmetry; at temperatures ~650 °C, it transforms into the cubic NaCl structure.[2]

To grow GeSe crystals, GeSe powder is vaporized at the hot end of a sealed ampule and allowed to condense at the cold end. Usual crystals are small and show signs of irregular growth, caused mainly by convective motion in the gaseous medium. However, GeSe grown under condition of zero-gravity and reduced convection aboard the Skylab are ~10 times larger than Earth-grown crystals, and are free from visual defects.[3][4]

References[edit]

  1. ^ L Makinistian et al (2007). "Ab initio calculations of the electronic and optical properties of germanium selenide". J. Phys.: C 19: 186211. doi:10.1088/0953-8984/19/18/186211. 
  2. ^ Wiedemeier H., Siemers P.A. (1975). "The Thermal Expansion and High Temperature Transformation of GeSe". Zeitschrift fur anorganische und allgemeine chemie 411: 90–96. doi:10.1002/zaac.19754110110. 
  3. ^ "SP-400 Skylab, Our First Space Station". NASA. Retrieved 2009-06-06. 
  4. ^ H. Wiedemeier et al. (1975). "Crystal growth and transport rates of GeSe and GeTe in micro-gravity environment". Journal of Crystal Growth 31: 36. doi:10.1016/0022-0248(75)90107-4.