Towards a rigorous definition of ferroic phase transitions

Abstract

Guymont's (Phys. Rev. B (1981), 24, 2647) nondisruption condition is made the basis for dividing phase transitions in crystals into nondisruptive and disruptive categories. Ferroic phase transitions are defined as nondisruptive phase transitions involving a change of point-group symmetry. Prototype symmetry is also defined rigorously in terms of the nondisruption condition. This approach forms the basis of a comprehcnsive and informative tensor-classification scheme for twinning in crystals (full details of which are published elsewhere), as also of a crystallographic classification of phase transitions.

Key Words:

• Ferroic phase transitions
• Prototype symmetry
• Orientation states
• Nondisruptive phase transitions
• Landau order parameter
• Ferroic order parameter