Schottky defect

Schottky defects consist of unoccupied anion and cation sites in a stoichiometric ratio.

Schottky defects are observed most frequently when there is a small difference in size between the cations and anions that make up a material.

This can be illustrated schematically with a two-dimensional diagram of a sodium chloride crystal lattice: The vacancies that make up the Schottky defects have opposite charge, thus they experience a mutually attractive Coulomb force.

Typical salts where Schottky disorder is observed are NaCl, KCl, KBr, CsCl and AgBr.

[citation needed] For engineering applications, Schottky defects are important in oxides with Fluorite structure, such as CeO2, cubic ZrO2, UO2, ThO2 and PuO2.

The defect-free NaCl structure
Schottky defects within the NaCl structure
Three bound configurations of Schottky defects in an oxide with Fluorite structure . Spheres represent atoms, cubes represent vacancies. [ 1 ]