Question

How do Frenkel defects affect the properties of crystals?

Answer 1

1. No Change in Density: Since no ions are lost from the crystal, the mass and volume remain the same, so the density is unaffected.
2. Electrical Conductivity Increases: The presence of vacant lattice sites and interstitial ions allows ions to move more freely, which increases ionic conductivity, especially at higher temperatures.
3. No Change in Stoichiometry: The number of cations and anions remains the same, so the chemical composition (stoichiometry) of the crystal does not change.
4. Lattice Distortion: The shift of ions from their normal positions to interstitial sites causes a slight distortion in the crystal lattice.
5. Dielectric Properties May Be Affected: The defect can influence dielectric behaviour due to the movement of charged particles within the lattice.