反铁电晶体Cs3H（SeO4）2对称性和序参量的研究

Study on symmetry and order parameter of antiferroelectric Cs3H（SeO4）2

在反铁电晶体Cs3H（SeO4）2顺电．反铁电相变中，对称性所属点群也随之发生相应的改变。通过对X射线衍射实验结果的分析，我们认为Cs3H（SeO4）2晶体反铁电相对称性所属点群为P2（C2）。选用轴矢量尺作为序参量来描述Cs3H（SeO4）2晶体反铁电相变中对称性的变化，应用居里原理，恰能得到Cs3H（SeO4）2晶体反铁电相的正确对称性所属点群P2（C2）。

On the bases of the result of X-ray diffraction at room temperature, the structure of antiferroelectric Cs3H（SeO4）2 has been studied in detail. For the paraelectric-antiferroelectric phase transition at 180K, this paper draw the conclusion that the symmetry of antiferroelectric Cs3H（SeO4）2 is P2（C2）. An axial rector R was selected as the order parameter to reflect the symmetry of antiferroelectric phase. According to Curie principle, the satisfying results are obtained relative to the change of symmetry group in the phase transition.