Question

Explain why does the presence of Frenkel defects not affect the density of a crystal.

Answer 1

1. The presence of Frenkel defects does not affect the density of a crystal because in this type of defect, no ions are removed from the crystal lattice.
2. Instead, a cation is displaced from its regular lattice site to an interstitial site (a vacant space within the crystal).
3. This creates a vacancy at the original position and an interstitial defect, but the total number of ions in the crystal remains the same.
4. Since density is defined as mass per unit volume, and neither the mass of the crystal changes (as no ion is lost) nor the volume is significantly altered, the overall density remains unaffected.

Thus, Frenkel defects involve a rearrangement of ions within the crystal, not a reduction in its mass.