A Frenkel defect, also called a Frenkel pair or Frenkel disorder, is a compound crystallographic defect in which an interstitial lies near the vacancy. Crystalline solids have a very regular atomic structure that is the local positions of atoms with respect to each other are repeated at the atomic scale Interstitials are a variety of Crystallographic defects, ie atoms which occupy a site in the Crystal structure at which there is usually not an atom or two or more atoms sharing In Crystallography, a vacancy is a type of Point defect in a Crystal. A Frenkel defect forms when an atom or ion leaves its place in the lattice (leaving a vacancy), and lodges nearby in the crystal (becoming an interstitial). History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge The phenomenon is named after the Russian physicist Yakov Frenkel. Russia (Россия Rossiya) or the Russian Federation ( Rossiyskaya Federatsiya) is a transcontinental Country extending Yakov Il'ich Frenkel, Яков Ильич Френкель ( February 10, 1894, Rostov-on-Don – January 23, 1952, Leningrad

For example, consider a lattice formed by X and M ions. Suppose an M ion leaves the M sublattice, leaving the X sublattice unchanged. The number of interstitials formed will equal the number of vacancies formed.

This can be illustrated with the example of the sodium chloride crystal structure. The diagrams below are schematic two-dimensional representations. This defect was discoverd by a russian scientist Frenkel in 1926. It arises when an ion is missing from its normal position and occupies an interstitial site between the lattice points.

The defect-free NaCl structure

Two Frenkel defects within the NaCl structure

See also

• Schottky defect
• Wigner effect

References

External links