Question

An ionic solid has some point defect but its experimental density is equal to its theoretical density. The type of defect is:

• A. Schottky defect
• B. Frenkel defect
• C. Metal excess defect
• D. Metal deficient defect

Answer 1

The correct option is B Frenkel defect

In Schottky defect, equal number of cations and anions are missing from their normal lattice sites and hence the density of crystalline solid decreases.
Frenkel defect is caused if some of the ions of the lattice occupy interstitial sites leaving a corresponding number of normal lattice sites vacant. Thus there is no change in the density of the solid.


In metal excess defect, metal ions or cations are in excess and oppositely in metal deficient defect the anions occupies the interstitial sites so basically it arises due to cation vacancies. So here density will not remain same in both the two cases.