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对于Kittel型反铁电相变，选择一个亚晶格的自发极化矢量P1/2或反极化参量P作为序参量是不合适的．本文具体讨论了相变前后对称性的变化，并由居里原理，给出此类相变序参量的正确形式，即，具有Cni的对称性．轴矢量R能很好地反映相变前后对称性的变化，可选作Kittel型反铁电相变的序参量．
For the Kittel-type antiferroelectric phase change, it is not appropriate to choose a sublattice spontaneous polarization vector P1 / 2 or a reverse polarization parameter P as the order parameter. In this paper, the changes of symmetry before and after phase transformation are discussed in detail, and the correct form of the parameters of such phase transitions is given by the Curie principle, that is, the symmetry of Cni is given. Axis vector R can well reflect the change of symmetry before and after phase change, which can be selected as the order parameter of Kittel type antiferroelectric phase transition.