AgCl is a common eg. for both Frenkel and Schottky Defect!How is it possible?In Frenkel, d size diference bw the cationic and d anionic part should b large nd in Schottky dif shud b less...How is it possible!!!

Schottky defect is observed in crystals having high coordination number and in which anion and cation have similar sizes. Such as NaCl.  Frenkel defect is observed in those crystals where there is large difference in size of cation and anion so that either cation or anion (generally smaller in size) can move into the interstitial site. Thus Frenkel defect is vacancy defect at that point from which anion or cation is replaced and interstitial defect where it is placed. AgCl show both because it has structure similar to that of NaCl. so it can show schottky defect or like a frenkel defect Ag + being smaller in size can move to interstitial site.

So we can conclude as that the Ag⁺ is small in size while Cl^- is large in size, which accounts for large differences in the size of anions and cation, thus show Frenkel deffect while AgCl is also highly ionic due to the same reason and hence show schottky defect.