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Larger defects in an ordered structure are usually considered dislocation loops. For historical reasons, many point defects, especially in ionic crystals, are called centers: for example a vacancy in many ionic solids is called a luminescence center, a color center, or F-center. These dislocations permit ionic transport through crystals leading ...
Category: Crystallographic defects. 15 languages. ... Download as PDF; Printable version; In other projects Wikimedia Commons; Wikidata item; Appearance. move to ...
Crystals inherently possess imperfections, sometimes referred to as crystallographic defects. Vacancies occur naturally in all crystalline materials. At any given temperature, up to the melting point of the material, there is an equilibrium concentration (ratio of vacant lattice sites to those containing atoms). [ 2 ]
Origin of title phenomenon in crystallographic defects. Shown is a two-dimensional slice through a primitive cubic crystal system showing the regular square array of atoms on one face (open circles, o), and with these, places where atoms are missing from a regular site to create vacancies, displaced to an adjacent acceptable space to create a Frenkel pair, or substituted by a smaller or larger ...
F-center in an NaCl crystal. An F-center or color center or Farbe center (from the original German Farbzentrum, where Farbe means color and zentrum means center) is a type of crystallographic defect in which an anionic vacancy in a crystal lattice is occupied by one or more unpaired electrons.
A Schottky defect is an excitation of the site occupations in a crystal lattice leading to point defects named after Walter H. Schottky. In ionic crystals , this defect forms when oppositely charged ions leave their lattice sites and become incorporated for instance at the surface, creating oppositely charged vacancies .
In diamond, only defects of the following symmetries have been observed thus far: tetrahedral (T d), tetragonal (D 2d), trigonal (D 3d, C 3v), rhombic (C 2v), monoclinic (C 2h, C 1h, C 2) and triclinic (C 1 or C S). [2] [4] The defect symmetry allows predicting many optical properties.
Weak beam dark field (WBDF) microscopy is a type of transmission electron microscopy (TEM) dark field imaging technique that allows for the visualization of crystal defects with high resolution and contrast. Specifically, the technique is mainly used to study crystal defects such as dislocations, stacking faults, and interfaces in crystalline ...