What is Schottky defect ?

Explanation

Schottky defect :
1) It is a point defect in which an atom or ion is missing from its normal site in the lattice .
2) In order to maintain electrical neutrality , the number of missing cations and anions are equal .
3) This sort of defect occurs mainly in highly ionic compounds , where cationic and anionic sizes are similar .
In such compounds the co-ordination number is high .
Ex . : NaCl , CsCl , etc .
4) Illustration :

5) This defect decreases the density of the substances .