Question

Due to Schottky defect, density of a crystal _________.

Answer 1

A Schottky defect is a type of point defect in a crystal lattice named after Walter H. Schottky. In non-ionic crystals it means a lattice vacancy defect.

In ionic crystals, the defect forms when oppositely charged ions leave their lattice sites, creating vacancies. These vacancies are formed in stoichiometric units, to maintain an overall neutral charge in the ionic solid. The vacancies are then free to move about as their own entities. Normally these defects will lead to a decrease in the density of the crystal. Schottky defects is a vacancy defect which lowers the density of the solid crystal.In this an equal number of cation and anion is missing from the interstitial site and this leads to the lowering of the density.