CBSE Class 12-science Answered
AgBr shows both Frenkel and Schottky defects because the radius ratio for AgBr is intermediate.
Explaination:
Ions have Schottky defects when their anions and cations are both absent from the crystal lattice.
In AgBr, the Ag+ ions and corresponding Br̶̶‒ ions are absent from the crystal lattice causing Schottky defects.
However, Ag+ ions are exceptionally mobile and they have a tendency to move about inside the lattice. So they complement the Schottky defects with Frenkel defects with the Ag+ ions trapped in interstitial spaces. Because of the similar size of Ag+ ions and Br‒ ions and the small size of Ag+ ions and the fact that Ag+ ions have a property to be mobile, both Schottky and Frenkel defects occur.