What type of stoichiometric defect is shown by ZnS ?

Frenkel defect or dislocation defect is observed in Zinc sulphide. This defect arises due to the hole in cationic lattice site and the cation occupying an interstitial position. This is because the size of the cation, i.e Zinc, is smaller than the anion and hence it occupies the interstitial site leaving behind a hole or vacant.