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Home > News & Articles > Frenkel Defects: Definitions, Examples, Characteristics, Calculation, Formula, Formation, Consequences, and Key Differences
Updated on 12th July, 2023 , 5 min read
When studying the molecular theory of the condensed state, Russian physicist Yakov Frenkel made the discovery of the Frenkel Defect. This finding was significant, though, since it helped to explain a flaw in crystalline solid molecules where an atom or ion would leave its original lattice site unfilled and occupy a different, intermediately vacant position on the same crystal. The flaw, often referred to as a dislocation Defect, also shows both self-interstitial and vacancy faults.
Soviet physicist Yakov Il'ich Frenkel, who lived from 10 February 1894 to 23 January 1952, is well known for his contributions to condensed matter physics. He also goes by the name Jacov Frenkel and is commonly referred to as J. Frenkel in English-language media.
When an atom or cation moves from its initial location in the lattice structure to fill a vacancy while occupying another interstitial position inside the solid crystal, the result is a point Defect known as a Frenkel defect. This flaw results in an interstitial flaw at the new site and a vacancy flaw at the previous site. A dislocation defect is another name for the Frankel Defects. The cation has relocated to a new location between the cations and anions, as seen in the picture, leaving its original lattice position unoccupied.
Ionic solids with a significant size difference between the cation and anion—the cation typically being smaller due to a higher effective nuclear charge—show Frenkel flaws. The following are some examples of solids with Frenkel flaws-
The crystal remains neutral and the balance of cations and anions is maintained in the Frenkel Defects, which is a rare Defects. The smaller atoms occupy the interstitial spaces because cations and anions differ in size. The following are the characteristics of Frenkel Defects-
The following are crucial factors to consider while determining how many Frenkel defects there are in a crystal-
The formula below may be used to compute Frenkel defects-
There are several ways that the Frenkel Defects might develop. The following is the list of processes that may be used to explain how the Frenkel Defects develop-
As the locations of molecules or atoms are established by the unit cell parameters in crystals at repeated set distances, defects are frequently seen in solid-state systems. Particle irradiation is typically used to engineer Frenkel flaws. The majority of a crystal's structure is flawed and unstable. The equilibrium in particle irradiation does not approach the detection limit because the enthalpy at the moment of creation is larger than it is at any other point. When the cation (smaller ion) is displaced in a structure, Frenkel Defects can also happen by accident.
The density and stability of the crystal are unaffected by the Frenkel Defects. The Defects directly affect the ion's movement, but they have no effect on the solid-state structure's volume or density. The interstitial atoms in densely packed formations cause stresses that cause the lattice to expand. This expansion outweighs the lattice's contraction as a result of the created void.
In ions, the Frenkel Defects result in a displacement. Due to the smaller cation ion's displacement from its original location and placement in an interstitial site, this Defect is also known as the dislocation Defect. The compounds have low coordination numbers and a significant variance in the sizes of the anions and cations, despite the fact that the density is unaltered.
In solid-state crystals, defects are caused by the development and seclusion of the crystals. Frenkel imperfection signifies the production of crystalline ionic compounds, whereas Schottky Defects highlight the imperfection in crystalline solids. The key differences between them are given below-
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By - Nikita Parmar 2023-08-25 09:48:44 , 11 min readIf part of the lattice's ions occupy interstitial sites while leaving a proportional number of regular lattice sites unoccupied, Frenkel Defects will result. AgCl, AgBr, AgI, ZnS, and other substances are examples of Frenkel defects.
AgBr's intermediate radius ratio causes it to exhibit both Frenkel and Schottky faults. When both of AgBr's anions and cations are missing from the crystal lattice, Schottky defects appear. The extremely mobile Ag+ ions have a propensity to migrate about inside the lattice. Additionally, they exhibit the Frenkel flaw.
Compounds of KCI, CsCI, and KBr exhibit Schottky Defects.
The Schottky Defects is a kind of crystal Defect when there are an equal number of cationic and anionic vacancies. The Frenkel Defect is a crystal Defect in which certain ions are shifted from regular lattice positions to interstitial locations.
Compounds of NaCl, Agl, and ZnS exhibit Frenkel Defects.
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