Direct observation of diffuse cone behavior in de Vries smectic-A and -C phases of organosiloxane mesogens.
Direct observation of diffuse cone behavior in de Vries smectic-A and -C phases of organosiloxane mesogens.
复制标题
直接观察有机硅氧烷介晶 de Vries 近晶 A 相和 C 相中的扩散锥体行为。
DOI：
10.1103/physrevlett.106.087801
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发表时间：
2011
影响因子：
8.6
通讯作者：
Satyendra Kumar
中科院分区：
文献类型：
--
作者：
H. Yoon;D. M. Agra;K. Ayub;R. Lemieux;Satyendra Kumar
通过X射线同时和直接测量两种有机硅氧烷介晶的脱弗里斯近晶A（SmA）和C（SmC）相的近晶层间距、分子倾斜和取向有序度，发现（i）SmC（倾斜）有序参数指数β=0.26±0.01，与二阶SmA-SmC转变的三临界行为非常一致;（ii）分子的硅氧烷和烃部分被分离并平行于指向矢取向，具有非常不同的取向有序度，以及（iii）有效分子长度的热演化在两相中不同。
Simultaneous and direct x-ray measurements of the smectic layer spacing, molecular tilt, and orientational order in the de Vries smectic A (SmA) and C (SmC) phases of two organosiloxane mesogens reveal that (i) the SmC (tilt) order parameter exponent β=0.26±0.01 for 2nd order SmA-SmC transition--in excellent agreement with the tricritical behavior, (ii) the siloxane and hydrocarbon parts of the molecules are segregated and oriented parallel to the director with very different degree of orientational order, and (iii) thermal evolution of the effective molecular length is different in the two phases.