In a solid lattice, the cation has left a lattice site and is located at an interstitial position, the lattice defect is :Interstitial defectValency defectFrenkel defectSchottky defect

The lattice defect described is a Frenkel defect. This type of defect occurs when an atom or ion vacates its place in the lattice and becomes an interstitial, occupying a space between the lattice points. This results in a vacancy defect at the atom's original position and an interstitial defect where the atom has moved to. This is different from a Schottky defect, which involves a paired vacancy of both a cation and an anion, and a valency defect, which involves an incorrect ratio of cations to anions.