Theoretical Studies Of Chiral Smectic Phases In Antiferroelectric Liquid Crystals
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Date
2015-02
Authors
TENG YONG, TAN
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Abstract
Antiferroelectric liquid crystals (AFLCs) are materials which are made up of chiral
elongated molecules. The molecules tilt around the azimuthal direction from layer to
layer and exhibit a number of smectic (Sm) tilted structures. These chiral smectic
structures have a variety of crystallographic unit periodicities which vary from a few
( * SmC ), two ( * SmCA ), three ( *
1 SmCFI ), four ( *
2 SmCFI ), and six ( *
6 SmC d ) smectic
layers.
In the first part of the project, the prerequisites for the formation of the sixlayer
structures are investigated theoretically using the discrete phenomenological
model. Such possible structures can be obtained when the sign of the coefficients for
the interactions of the nearest neighbor, third nearest neighbor, and quadrupolar
coupling are considered explicitly. For the second part of the project, the dependence
of the polarization direction on the structures of the * SmC , *
2 SmC , FI and *
1 SmCFI
phases are analyzed within the framework of the clock model. The influence of the
flexoelectric coefficient and the deviation angle on these chiral smectic
structures are shown as well. In the third and last part of this project, the discrete
phenomenological model is applied to study theoretically the dielectric response of
chiral smectic phases, particularly in * SmC and * SmCA phases, under the influence
of external harmonic electric field. The numerical results of frequency dependence of
dielectric loss as well as the variation of dielectric loss in quadrupolar coupling
strength for the * SmC and *
A SmC phases are obtained and presented.
Description
Keywords
Theoretical Studies Of Chiral Smectic Phases , In Antiferroelectric Liquid Crystals