Term: Mott transition
https://doi.org/10.1351/goldbook.M04037

Definition:
A transition occurring only in 'single-valent' systems from strongly correlated (U > W) to weakly correlated (U < W) electrons as a result of a change of bandwidth W. W reflects the strength of the interatomic interactions in a periodic array of like atoms and U is a measure of the intra-atomic interactions, i.e. the electrostatic energy involved in the creation of polar states by transferring an electron from one atom to the next, as shown schematically by the disproportionation reaction: \[\text{M}^{n+}+\text{M}^{n+}\rightarrow \text{M}^{(n+1)+}+\text{M}^{(n- 1)+}\] A U > W produces a magnetic semiconductor; a U < W gives rise to a metal (normally nonmagnetic). Note also that U and W can be altered by changes in interatomic distances, brought about through temperature or pressure variations or by introducing an alloying element. Synonymous with Mott–Hubbard transition.

Related Terms:
1) disproportionation (http://doi.org/10.1351/goldbook.D01799).
2) semiconductor (http://doi.org/10.1351/goldbook.S05591).

Source: PAC, 1994, 66, 577. 'Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)' on page 587 (https://doi.org/10.1351/pac199466030577)

Citation: 'Mott transition' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.M04037

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