whta type of crystal defect is produced when NaCl is doped with MgCl2?

When NaCl is doped with MgCl₂, each Mg²⁺ ion replaces 2 Na⁺ ions to maintain electrical neutrality. One site is occupied by Mg²⁺ ion while the other remains vacant. Thus, cation vacancies are introduced. This defect is called impurity defect.