Nature of smectic A*-C* phase transitions in a series of ferroelectric liquid crystals with little smectic layer shrinkage.
Nature of smectic A*-C* phase transitions in a series of ferroelectric liquid crystals with little smectic layer shrinkage.
复制标题
一系列近晶层收缩较小的铁电液晶中近晶 A*-C* 相变的性质。
DOI：
10.1063/1.2432886
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
F. Giesselmann
中科院分区：
文献类型：
--
作者：
S. Bezner;M. Krueger;V. Hamplová;M. Glogarová;F. Giesselmann
近晶层间距的两个同源系列的铁电液晶化合物，其特征在于通过小角X-射线衍射和不同程度的近晶层收缩从SmA* 冷却到SmC* 相进行了观察。通过测量热场和电场对光倾角和电极化的影响，进一步研究了近晶A ~*-近晶C ~* 相变。随着烷基末端链长度的减小，相变从三临界的表现出高的层收缩到几乎没有层收缩的纯二阶转变。这可以通过近晶层的增加的一维平移顺序来解释，这似乎促进了“de弗里斯”型[Mol.结晶液Cryst.41，27（1977）]近晶A*-C* 相变，没有或几乎没有层收缩。
The smectic layer spacing of two homologous series of ferroelectric liquid crystal compounds was characterized by small-angle x-ray diffraction and different degrees of smectic layer shrinkage on cooling from the SmA* into the SmC* phase were observed. The smectic A*-smectic C* phase transition was further studied by measuring the thermal and electric field effects on the optical tilt angle and the electric polarization. With decreasing length of the alkyl terminal chain the phase transition changes from tricritical exhibiting high layer shrinkage to a pure second-order transition with almost no layer shrinkage. This is explained by the increased one-dimensional translational order of the smectic layers, which seems to promote the "de Vries"-type [Mol. Cryst. Liq. Cryst. 41, 27 (1977)] smectic A*-C* phase transition with no or little layer shrinkage.