Frenkel defect
Shown by ionic solids containing large differences in the sizes of ions
Created when the smaller ion (usually cation) is dislocated from its normal site to an interstitial site
Creates a vacancy defect as well as an interstitial defect
Also known as dislocation defect
Ionic solids such as AgCl, AgBr, AgI and ZnS show this type of defect.
Schottky defect
Basically a vacancy defect shown by ionic solids
An equal number of cations and anions are missing to maintain electrical neutrality
Results in the decrease in the density of the substance
Significant number of Schottky defect is present in ionic solids. For example, in NaCl, there are approximately 106 Schottky pairs per cm3, at room temperature.
Shown by ionic substances containing similar-sized cations and anions; for example, NaCl, KCl CsCl, AgBr
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Frenkel defect
Shown by ionic solids containing large differences in the sizes of ions
Created when the smaller ion (usually cation) is dislocated from its normal site to an interstitial site
Creates a vacancy defect as well as an interstitial defect
Also known as dislocation defect
Ionic solids such as AgCl, AgBr, AgI and ZnS show this type of defect.
Schottky defect
Basically a vacancy defect shown by ionic solids
An equal number of cations and anions are missing to maintain electrical neutrality
Results in the decrease in the density of the substance
Significant number of Schottky defect is present in ionic solids. For example, in NaCl, there are approximately 106 Schottky pairs per cm3, at room temperature.
Shown by ionic substances containing similar-sized cations and anions; for example, NaCl, KCl CsCl, AgBr
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Frenkel defect-It arises when an ion,usually cation leaves its normal site and occupies an interstitial site.This defect is usually observed in compiunds having low co-ordination no.e.g-AgCl
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When some ions are missing from the lattice sitesand they occupy the intetstitial sites so that electrical neutrality as well as stoichioemetry is maintained it is called frenkal defect.
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But in schottky defect equal number of cations and anions are missing from their lattice site . Density decreases in this defect.
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Frenkel Defect?is one type of point defect where an atom (better to say ion, especially cation) leaves its original lattice site and occupies an interstitial position on the same crystal. Usually, this type of defect is observed in ionic solids, where size of anion is substantially larger than the size of cation.?
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(a) Schottky Defect:?This defect is caused if some of the lattice points are unoccupied. The points which are unoccupied. The points which are unoccupied are called lattice vacancies. The number of missing positive and negative ions is the same in this case and the crystal remains neutral. The existence of two vacancies, one due to a missing?Na+?ion and the other due to a missing?Cl??ion in a crystal of?NaCl. It appears in ionic crystals in which positive and negative ions do not differ much in size.
Frenkel Defects:?This defect arise when an ion occupies an interstitial position between the lattice points. This defect occurs generally in ionic crystals in which the anion is much larger in size than the cation.
AgBr?is an example for this type of defect. One of the?Ag+?ion occupies a position in the interstitial space rather than its own appropriate site in the lattice.
The crystal remains neutral since the number of positive ions is the same as the number of negative ions.
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Frenkel defect - This defect is shown by ionic solid. The smaller ion is dislocated from its normal site to an interstitial site. It creates a vacancy defect at its original site and an interstitial defect at its new location.
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* Frenkel defect ?? This defect is also shown by ionic solid. The smaller ion dislocated from its normal site to interstitial site
*This defect is aloso known as dislocation defect
Ex Agcl, Zns ,AgI , AgBr
* Note* AgBr shows both frenkel and schottky defects......
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