Question

explain the schottky defect created in AgCl when doped with ions and CdCl2

Answer 1

Doping of AgCl with CdCl₂ produces impurity defect and not Schottky defect.

Here an added compound creates a defect. In Schottky defect, no impurity is added and vacancies are created due to loss of equal number of cations and anions.
In the above case, when a divalent Cd ion replaces monovalent silver ion, then another silver ion leaves the lattice to maintain neutrality. There is no loss of anion as expected in Schottky defect.