Question

Schottky defect in a crystal is observed when:

• A. Some cations move from their lattice site to interstitial sites
• B. Equal number of cations and anions are missing form the lattice
• C. Some lattice sites are occupied by electrons
• D. Some impurity is present in the lattice

Answer 1

The correct option is B

Equal number of cations and anions are missing form the lattice

• The Schottky defect is a type of point defect.
• Schottky defect in crystals is observed when equal numbers of cations and anions are missing from the lattice.

Characteristics of Schottky Defect:

• There is a very small difference in size between cation and anion.
• Cation and anion both leave the solid crystal.
• Atoms also move out of the crystal permanently.
• Generally, two vacancies are formed.
• The density of the solid decreases considerably.

Therefore, option B is correct.