Question

Write the consequences of Schottky defect with reasons.

Answer 1

Consequences of Schottky defects are:

1. As the number of ions decreases, mass decreases. However, volume remains unchanged. Hence, the density of a substance decreases.
2. The number of missing cations and anions is equal, and the electrical neutrality of the compound is preserved.
3. This defect is found in ionic crystals such as NaCl, AgBr and KCl.
4. Since some ions are missing from the crystal lattice, the mass of the crystal decreases without a corresponding change in volume.
5. The overall density of the crystal decreases.
6. Equal numbers of positive and negative ions are missing, so there is no net charge.
7. The electrical neutrality of the crystal is preserved.
8. The ratio of cations to anions remains the same because equal numbers are missing.
9. The chemical formula of the compound remains unchanged.
10. The presence of vacant sites may allow ions to move slightly under an electric field.
11. There is a small increase in ionic conductivity, especially at higher temperatures.