Why silver halides show frenkel defect?

Silver halides, such as AgCl, AgBr, and AgI, exhibit Frenkel defects due to the small size of silver ions compared to the halide ions. In a Frenkel defect, a cation (in this case, Ag+) is displaced from its lattice position and occupies an interstitial site, creating a vacancy in its original position. This defect is favored because it allows for the accommodation of the smaller silver ions without significantly distorting the crystal lattice. As a result, Frenkel defects enhance the ionic conductivity of silver halides, making them useful in various applications, including Photography and as semiconductors.