What is imperfection in solids?

Match the imperfection in solids with the characteristic features.

Imperfections In Solids

Bragg''''s Equation,Defects or imperfections in Solids Schottky and Frenkel Defects, Non Stoichiometric Defects,Magnetic Properties,Piezoelectricity and Pyroelectricity

Fungi imperfect is

What do you understand by imperfections in ionic crystals? Name the types of imperfections which generally occur in ionic crystals

What do you understand by imperfections in ionic crystals ? Name the types of imperfections which occur in ionic crystals.