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- F-Center abstract "An F-Center or Farbe (German for colour) center is a type of crystallographic defect in which an anionic vacancy in a crystal is filled by one or more electrons, depending on the charge of the missing ion in the crystal or mainly due to the reason that when a compound is heated to a high temperature (mainly metallic oxides) the ions get excited and get displaced from their respective positions in their crystal structure but while doing so these ions leave behind some electrons in the vacated spaces. This leads to the phenomenon of colouring of compounds. This is used to identify many compounds, especially zinc oxide (yellow). Electrons in such a vacancy tend to absorb light in the visible spectrum such that a material that is usually transparent becomes colored. Thus the origin of the name, F-center, which originates from the German Farbzentrum. The translation of this term also provides the synonym color center, which can also refer to such defects. F-centers are often paramagnetic and can then be studied by electron paramagnetic resonance techniques. The greater the number of F-centers, the more intense is the color of the compound. A way of producing F centers is to heat a crystal in the presence of an atmosphere of the metal that constitutes the material, e.g.: NaCl heated in a metallic Na atmosphere.Na0 → Na+ + e−Na+ is incorporated at NaCl crystal.Cl− vacancies are generated, because of the excess of Na+.These vacancies capture available e-, neutralizing and forming F-centers; that is, the electrons released in this process diffuse to occupy the vacant places. Also, ionizing radiation can produce F-centers.An H-center (a halogen interstitial) is in a sense the opposite, and hence a F-center and a H-center can combine and clear the lattice of a defect. This process can be photoinduced, e.g. by a laser.".
- F-Center thumbnail NaCl_-_F-center.jpg?width=300.
- F-Center wikiPageExternalLink lookup.asp?url=lookup&entrynum=902&letter=c.
- F-Center wikiPageID "552965".
- F-Center wikiPageRevisionID "589444312".
- F-Center hasPhotoCollection F-Center.
- F-Center subject Category:Crystallographic_defects.
- F-Center type Abstraction100002137.
- F-Center type Attribute100024264.
- F-Center type CrystallographicDefects.
- F-Center type Defect114464005.
- F-Center type Imperfection114462666.
- F-Center type State100024720.
- F-Center comment "An F-Center or Farbe (German for colour) center is a type of crystallographic defect in which an anionic vacancy in a crystal is filled by one or more electrons, depending on the charge of the missing ion in the crystal or mainly due to the reason that when a compound is heated to a high temperature (mainly metallic oxides) the ions get excited and get displaced from their respective positions in their crystal structure but while doing so these ions leave behind some electrons in the vacated spaces. ".
- F-Center label "Centro de color".
- F-Center label "Centro di colore".
- F-Center label "F-Center".
- F-Center label "F-centrum".
- F-Center label "Farbzentrum".
- F-Center label "Центры окраски".
- F-Center sameAs Farbzentrum.
- F-Center sameAs Centro_de_color.
- F-Center sameAs Centro_di_colore.
- F-Center sameAs F-중심.
- F-Center sameAs F-centrum.
- F-Center sameAs m.02p86k.
- F-Center sameAs Q905180.
- F-Center sameAs Q905180.
- F-Center sameAs F-Center.
- F-Center wasDerivedFrom F-Center?oldid=589444312.
- F-Center depiction NaCl_-_F-center.jpg.
- F-Center isPrimaryTopicOf F-Center.
