Answer:
Schottky
defect A Schottky defect consists of a pair of 'holes' in the crystal
lattice. One positive ion and one negative ion are absent. This defect occurs mainly
in highly ionic compounds when the positive and negative ions are of a similar
size and hence the coordination number is high (usually of 8 or 6). Examples
NaCI, CsCI, KCI. Density of the crystal is lowered.
[1]
(ii)
Frenkel defect A Frenkel defect consists of a vacant lattice site (hole)
and the ion which ideally should have occupied the site now occupies an interstitial
position. This type of defect is favoured by a large difference in size of
cations and anions and thus with low coordination number. (4 or 6).
Examples
ZnS, AgCI, AgBr, and Agl. [1]
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