Schottky defect is observed in crystals when __________.


The Schottky defect is basically a kind of vacancy defect with the tendency to maintain electrical neutrality, therefore same no.s of cations are anions are missing from the crystal lattice.



Other 3 options are incorrect.


(i) some of the cations move from their lattice site to interstitial sites – this occurs in the case for Frankel defect only.


some lattice sites are occupied by electrons- this is the case of metal excess defect.


(iv) some impurity is present in the lattice – this is observed in crystals with impurity defects.

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