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polymorphic transition

A reversible transition of a solid crystalline phase at a certain temperature and pressure (the inversion point ) to another phase of the same chemical composition with a different crystal structure.
In a liquid-crystal transition, this term refers to phase changes in the smectic state or columnar discotic state.
  1. The transitions of SiO2 (quartz-type) at 1143 K to SiO2 (tridymite-type), and at 1743 K to SiO2 (cristobalite-type).
  2. The transition of β-AgI (wurtzite-type structure) to α-AgI (body-centred-cubic structure) at 418 K. Synonymous with enantiotropic transition.
PAC, 1994, 66, 577 (Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)) on page 588
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IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook.
Last update: 2014-02-24; version: 2.3.3.
DOI of this term: doi:10.1351/goldbook.P04748.
Original PDF version: http://www.iupac.org/goldbook/P04748.pdf. The PDF version is out of date and is provided for reference purposes only. For some entries, the PDF version may be unavailable.
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