Question

Which of the following statements are correct in context of point defects in a crystal?

• A. $AgCl$ has anion Frenkel defect and $CaF_{2}$ has Schottky defects
• B. $AgCl$ has cation Frenkel defects and $CaF_{2}$ has anion Frenkel defects
• C. $AgCl$ and $CaF_{2}$ have anion Frenkel defects
• D. $AgCl$ and $CaF_{2}$ have Schottky defects

Answer 1

Answer: (B)

Since $Ag^{+}$ (cation) is smaller than $Cl^{-}$ (anion) and hence cation is present in voids.
In $CaF_{2},Ca^{2+}$ is smaller.