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where N v is the vacancy concentration, Q v is the energy required for vacancy formation, k B is the Boltzmann constant, T is the absolute temperature, and N is the concentration of atomic sites i.e. = where ρ is density, N A the Avogadro constant, and M the molar mass. It is the simplest point defect.
For example, the defect may result in an ion on its own ion site or a vacancy on the cation site. To complete the reactions, the proper number of each ion must be present (mass balance), an equal number of sites must exist (site balance), and the sums of the charges of the reactants and products must also be equal (charge balance).
An F center is ionized and becomes a vacancy; the electron moves through the material to bind to another F center, which becomes an F − center. The electron vacancy moves through the material and ends up next to the F − center, which gives its electron back to the vacancy, forming two neighbouring F centers, i.e. an F 2 center.
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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 .
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 ...
In crystallography, a Frenkel defect is a type of point defect in crystalline solids, named after its discoverer Yakov Frenkel. [1] The defect forms when an atom or smaller ion (usually cation) leaves its place in the structure, creating a vacancy and becomes an interstitial by lodging in a nearby location. [2]
The defect concentration diagram (also problem concentration diagram [1]) is a graphical tool that is useful in analyzing the causes of the product or part defects. [2] It is a drawing of the product (or other item of interest), with all relevant views displayed, onto which the locations and frequencies of various defects are shown.