Molecular model for de Vries type smectic- A -smectic- C phase transition in liquid crystals.
نویسندگان
چکیده
We develop both phenomenological and molecular-statistical theory of smectic- A -smectic- C phase transition with anomalously weak smectic layer contraction. Using a general mean-field molecular model, we demonstrate that a relatively simple interaction potential suffices to describe the transition both in conventional and de Vries type smectics. The theoretical results are in excellent agreement with experimental data. The approach can be used to describe tilting transitions in other soft matter systems.
منابع مشابه
Order-disorder molecular model of the smectic-A-smectic-C phase transition in materials with conventional and anomalously weak layer contraction.
We develop a molecular-statistical theory of the smectic-A-smectic-C transition which is described as a transition of the order-disorder type. The theory is based on a general expansion of the effective interaction potential and employs a complete set of orientational order parameters. All the order parameters of the smectic-C phase including the tilt angle are calculated numerically as functio...
متن کاملde Vries behavior in smectic liquid crystals near a biaxiality-induced smectic- A-smectic-C tricritical point.
We show that a generalized Landau theory for the smectic-A-smectic-C (Sm- A -Sm- C ) phases exhibits a biaxiality induced Sm- A -Sm- C tricritical point. Proximity to this tricritical point depends on the degree of orientational order in the system; for sufficiently large orientational order the Sm-A-Sm-C transition is three-dimensional XY -like, while for sufficiently small orientational order...
متن کاملExperimental demonstration, using polarized Raman and infrared spectroscopy, that both conventional and de Vries smectic-A phases may exist in smectic liquid crystals with a first-order A-C* transition.
Two models exist for the orientational distribution of the long molecular axes in smectic-A liquid crystals: the conventional unimodal distribution and the "cone-shaped" de Vries distribution. The de Vries hypothesis provides a plausible picture of how, at a molecular level, a first-order Sm-A to Sm-C* transition may occur, especially if there is little or no concomitant shrinkage of the layer ...
متن کاملElectro-optic and dielectric study of the de Vries-type smectic-A* phase exhibiting transitions to smectic-C*A and smectic-C* phases.
Mixtures of different compositions of an antiferroelectric liquid crystal compound that exhibits direct smectic-A*(Sm-A*)-smectic-C*(A) (Sm-C*(A)) transition with a ferroelectric liquid crystal compound that exhibits Sm-A*-smectic-C*(Sm-C*) transition are studied using electro-optics and dielectric spectroscopy. The results of optical texture, birefringence, and the tilt angle suggest that a pa...
متن کاملEvidence for de Vries structure in a smectic-A liquid crystal observed by polarized Raman scattering.
The second- and fourth-order apparent orientational order parameters of the core part of the molecule P2 (app) and P4 (app) , have been measured by polarized vibrational Raman spectroscopy for a homogeneously aligned ferroelectric smectic liquid crystal with three dimethyl siloxane groups in the achiral terminal chain, which shows de Vries-type phenomena, i.e., very large electroclinic effect i...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Physical review. E, Statistical, nonlinear, and soft matter physics
دوره 75 6 Pt 1 شماره
صفحات -
تاریخ انتشار 2007