difference between schottky defect and frenkel defect
1. in this type of defect equal no of ions are missing from their original site.
2.shown by ionic compounds which have almost similar size of cations and anions.
3. decreases the density of a crystal.
for eg- NaCl, KCl
*its a type of vacany defect.
1. this is shown by ionic solids where smaller ions usually cations is located from its original site to an interstitial site .
2. shown by ionic compounds in which there is a large difference in the size of ions.
3. does not effect the density of crystal
for eg - AgCl, AgBr .
* its a type of interstitial defect.
A Schottky defect is when 2 oppositely charged ions leave their normal lattice positions forming 2 vacancies in the lattice structure.
This contrasts to a Frenkel defect, where 1 ion simple moves from it's normal lattice position to an interstitial site (tetrahedral/octahedral hole).
1. Equal number of cations and anions are missing from the lattice sites.
2. Found in highly ionic compounds with high coordination numbers and where the cations and anions are of similar size.
3. Density of the solid decreases
1. A cation leaves the normal lattice site and occupies an interstitial site.
2. Found in ionic compounds with low coordination numbers and where the anions are much larger in size than cations.
3. Density of the solid remains the same.
* coordination number: It is defined as the number of nearest neighbours of a particle in a closed packed structure.
1- this type of defect represent by ionic in which cation have small size then anion
2- such type of defect represent by ionic solid have low co-ordination number
Ex- Agcl, zns
1- such type of defect represent by ionic solid in which cation and anion have almost equal size
2- such type of defect represent by ionic solid have high co- ordination number
Ex- Nacl , NaBr
In schottky defect equal number of cations and anions are missing from their lattice sites. Density of crystal decreass in this defect.