What type of crystal defect is produced when ' NaCl' is:doped with 'MgCl_2'

Options

A. interstitial
B. Frenkel
C. impurity defect
D. None of these

Answer

C

Explanation

When small amount of `MgCl_(2)` is added to NaCl, some of the `Mg^(2+)` ions replace `Na^(+)` ions and occupy the sites earlier occupied by `Na^(+)`. To maintain electrical neutrality of the crystal one more `Na^(+)` leaves the lattice, thus generating, cation vacancy equal to number of `Ca^(2+)` ions added. Thus impurity defect is produced.