Why AgBr shows both Schottky and Frenkel defects??

Asked by vaish.agrawal | 11th Jun, 2015, 11:56: PM

Expert Answer:

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 Agions and the fact that Ag+ ions have a property to be mobile, both Schottky and Frenkel defects occur.

Answered by Hanisha Vyas | 12th Jun, 2015, 11:02: AM