Question

What type of stoichiometric defect is shown by: $\mathrm{AgBr}$

Answer 1

Stoichiometric defect:

• “The point defects that do not disturb the stoichiometry of the solid are called stoichiometric defects.”
• They are also known as thermodynamic or intrinsic defects.

$\mathbf{AgBr}$

• $\mathrm{AgBr}$ (Silver) has an intermediate radius ratio.
• It exhibits both Frenkel and Schottky defects.
• In crystalline solids, a defect known as the Frenkel Defect occurs when atoms are moved from their lattice positions to interstitial sites, leaving a void at the lattice point.
• It typically happens in ionic solids where the ions' sizes differ greatly.
• When both of the ion's anions and cations are missing from the crystal lattice, the ions exhibit Schottky defects.
• Since the Silver $\left({\mathrm{Ag}}^{+}\right)$ and Bromide $\left({\mathrm{Br}}^{-}\right)$ ions are missing from the crystal lattice in $\mathrm{AgBr}$, Schottky defects result.