立方晶系晶体本征铁弹相变序参量的选取

Selection of Order Parameter of Proper Ferroelastic Phase Transitions of Cubic Crystals

在本征铁弹相变的软模理论的基础上,依据弹性本构关系和居里原理,给出了立方晶系晶体所有可能的自发应变的种类,研究了立方晶系晶体本征铁弹相变序参量的选取问题。以Th群和Oh群为例,阐明了不同类的序参量导致晶体对称性变化相同的的原因,提出了该情况下序参量选取的"就少不就多"的原则。得到了发生本征铁弹相变时所有可能的序参量及晶体的对称性的变化。

Based on the soft mode theory of proper ferroelastic phase transitions,all of possible kinds of spontaneous strains of cubic crystals were given by using elastic constitutive relations and the Curie principle. Selection of order parameters of proper ferroelastic phase transitions was studied. The reason of different kinds of order parameter corresponding to the same change of symmetry was clarified by analyzing group Thand group Oh. In this condition,the principle which is choosing the order parameter with lower symmetry instead of with higher symmetry was put forward. All of the possible order parameters and the symmetry change of proper ferroelastic phase transitions of cubic crystals were obtained.