A transition in which the space-group symmetry of the lower symmetry phase is a subgroup
of that of the higher symmetry phase. Example: The transition of the low-temperature
polymorph of quartz characterized by space-group symmetry
(trigonal), to the high temperature polymorph of quartz with space-group symmetry,
(hexagonal). Synonymous with
symmetry-breaking transition (note: this term, strictly speaking, is no longer in use).
Source:
PAC, 1994, 66, 577
(Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations
1994))
on page 591
Cite as:
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.
https://doi.org/10.1351/goldbook.
