What is Schottky defect?
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What is Schottky defect?
Definition of Schottky defect : a defect in a crystal lattice created by removing an ion from its normal site and placing it on the crystal surface.
What is Schottky defect in a crystal explain with examples?
Schottky defect: Schottky defect is basically a vacancy defect shown by ionic solids. In this defect, an equal number of cations and anions are missing to maintain electrical neutrality. Ionic substances containing similar-sized cations and anions show this type of defect. For example: NaCl, KCl, CsCl, AgBr, etc.
What are Schottky and Frenkel defect?
Schottky defect occurs in those ionic crystals where the difference in size between cation and anion is small. Frenkel defect usually occurs in those ionic crystals where size of anion is quite large as compared to that of the cation. In Schottky defect, both cation and anion leave the solid crystal.
How do I find my Schottky defect?
The number of Schottky defects (n) present in an ionic compound containing N ions at temperature Tis given by n = Ne E/2KT, where E is the energy required to create ‘n’ Schottky defects and K is the Boltzmann constant. If the mole fraction of Schottky defect in NaCl crystal at 2900 K is X.
What is interstitial defect example?
An interstitial defect is a type of point crystallographic defect where an atom of the same or of a different type, occupies a normally unoccupied site in the crystal structure. When the atom is of the same type as those already present they are known as a self-interstitial defect.
What are consequences of Schottky defect?
Since the number of ions (cations and anions) decreases but volume remains unchanged, the density of a substance decreases. As the number of missing cations and anions is equal, the electrical neutrality of the compound remains same.
What are the conditions and consequences of Schottky defect?
Presence of large number of Schottky defect lowers the density of the crystal. When Frenkel defect alone is present, there is no decrease in density. The closeness of the charge brought about by Frenkel defect tends to increase the dielectric constant of the crystal.
What is Schottky defect Ncert 12?
-A Schottky defect is a type of vacancy defect which is found in ionic solids. It is a stoichiometry defect (thermodynamic defect), which means that such defects do not change or distort the stoichiometry of the solid.
Is Schottky defect and interstitial defect?
It is a type of vacancy defect. Schottky defect reduces the density of substances and the size of anions and cations are the same. In the Frenkel defect, displacement of ions of the crystals takes place in which the smaller ion like cation gets displaced from its normal site to an interstitial site.
What is self interstitial defect?
What is vacancy defect class 12?
1. Vacancy defect:- When is in a crystalline substance, some of the lattice sites are vacant the crystal is said to have vacancy defect it results in decrease of density of substance.
What are consequences of Schottky?
What is Schottky and Frenkel defects?
What is Schottky and Frenkel defects? Schottky defect occurs in those ionic crystals where difference in size between cation and anion is small. In Schottky defect, both cation and anion leave the solid crystal. In Frenkel defect, only the smaller ion (cation) leaves its original lattice site; whereas, the anion remains in original lattice sites.
What is Schottky defect in ionic crystal?
In Schottky defect, one cation and one anion leave their lattice sites to create two vacancies. Schottky defects occur in ionic crystals where the size of anion is almost same with the size of the cation. One anion and one cation leave the crystal at the same time to create Schottky defect. None of them occupies the interstitial site again.
How does Frenkel defect and Schottky defect differ?
Schottky defect and Frenkel defect are two types of point defects found in crystal lattices. The main difference between Schottky defect and Frenkel defect is that Schottky defect reduces the density of the crystal whereas Frenkel defect does not have any impact on the density of the crystal .
What is the Schottky effect?
Schottky effect, increase in the discharge of electrons from the surface of a heated material by application of an electric field that reduces the value of the energy required for electron emission. The minimum energy required for an electron to escape the surface of a specific material, called the work function, is supplied by the heat.