θ相变的序参量及对称性的研究

On the Study of Parameter and Symmtry of Phase Transition

给出了一个三阶全对称的电学量作为θ 相变的序参量，并且分别计算出了PZT、SrTiO3晶体θ相 ∏ijk 的各个分量．将计算出的这两种晶体 θ 相的 ∏ijk 矩阵与三阶全对称张量 的矩阵表相比较，得出PZT、SrTiO3晶体 θ 相 ∏ijk 所属对称群分别为D3、D2d．按照居里原理，这一序参量能很好的说明相变前后对称性的变化．

：A third-order complete symmetry polarization tensor∏ijk is pu t forward as the order parameter of ∏ijk phase transition.The matrix of θ has been calculated for PZT and SrTiO3 respectively.Comparing the r esults for these two crystals of∏ijk phase to the matrix tabular of thi rd-order complete symmetry tensor ∏ijk ,we can receive the symmetry g roups of two crystals' tensor ∏ijk of θ phase,that is,PZT is D3 ,and SrTi O3 is D2d .According to the Curie principle,The order parameter can r eflect the symmetry changes perfectly.