Acta Crystallographica Section A

Foundations of Crystallography

Volume 58, Part 4 (July 2002)

research papers

Acta Cryst. (2002). A58, 327-333 [ doi:10.1107/S0108767302005287 ]

Group-theoretical and geometrical considerations of the phase transition between the high-temperature polymorphs of quartz and tridymite

H. Sowa and E. Koch

Abstract: A model was derived for the temperature-dependent phase transition between the high-temperature polymorphs of quartz (P6₄22) and tridymite (P6₃mmc). Only the Si framework is considered, and the transformation can be described as a deformation of a homogeneous sphere packing with three contacts per sphere (type 3/10/h1) in the common subgroup P6₁22 of P6₄22 and P6₃mmc. The proposed model guarantees the three-dimensional connection of the crystal structure during the whole transformation process.

Keywords: phase transitions; quartz; tridymite; sphere packings.