What are stoichiometric defects or intrinsic defects in ionic crystals ?

Stoichiometric defects are inherent flaws in which the cation-to-anion ratio remains constant as expressed by the molecular formula.

They are primarily of two types:

Vacancy defect

A vacancy defect occurs when an atom is not present at one of its lattice sites, causing that lattice site to be vacant.

The density of a substance will decrease as a result of this flaw.

Interstitial defect

An atom or molecule occupying the intermolecular spaces or interstitial sites in crystals is known as an interstitial defect.

The density of the substance increases as a result of this fault.

Hence, stoichiometric defects or intrinsic defects in ionic crystals are inherent flaws in which the cation-to-anion ratio remains constant as expressed by the molecular formula