It is also known as a Schottky defect, although in ionic crystals the concepts are not identical.

A vacancy (or pair of vacancies in an ionic solid) is sometimes called a Schottky defect.

To be noted : AgBr shows both Frenkel as well as Schottky defects.

A Schottky defect is an intrinsic point defect that creates vacancies on both the cation and anion sub-lattices.

A Schottky defect is when 2 oppositely charged ions leave their normal lattice positions forming 2 vacancies in the lattice structure.

A Schottky defect is a type of point defect in a crystal lattice named after Walter H. Schottky.

Therefore, given a temperature and the formation energy of Schottky defect, the intrinsic Schottky defect concentration can be calculated from the above equation.

However, due to the loss of ions within the crystal lattice, these Schottky defects tend to lead to a decrease in the density of the material because vacancies have been created.

The following are the chemical equations in Kröger-Vink Notation for the formation of Schottky defects in TiO and BaTiO.

At higher temperatures the diffusivity increases due to the direct temperature dependence of the equation, the increase in vacancies through Schottky defect formation, and an increase in the average energy of atoms in the material.

Similarly to Schottky defect, a Frenkel defect is an intrinsic point defect that produces a vacancy site on either the cation or anion sub-lattice along with an interstitial site on that same lattice.

If in an ionic crystal of type AB an equal number of cations and anions are missing from their lattice sites so that electrical neutrality as well as stoichiometry is maintained this is called a Schottky Defect.

Stoichiometric oxides have an integer ratio of atoms can only support coupled diffusion of anions and cations through the lattice migration of Schottky defects (paired anion/cation vacancies) or Frenkel defects (complete anion lattice with cation vacancies and intersticials).