Due to $Frenkel$ defect,the density of ionic solids

What kind of defects do most ionic crystals possess?

Explain how vacancies are introduced in an ionic solid when a cation of higher valence is added as an impurity in it.

What causes the formation of a $Schottky$ defect?

The formula of a metal oxide is $M_{0.96} O_1$. The fractions of metal that exist as $M^{3+}$ and $M^{2+}$ ions in that oxide are respectively

Compounds with low coordination numbers of cations and anions exhibit Frenkel defects because the compound has ................