Which type of defect has the presence of cations in the interstitial sites?

A Frenkel defect is a type of point defect in crystalline solids where an atom is displaced from its lattice position to an interstitial site. This creates a vacancy at the original lattice site and an interstitial atom at a new site. In ionic crystals, this often involves a cation (positively charged ion) moving to an interstitial site because cations are generally smaller than anions.