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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:42 |
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Conference: Bucharest University Faculty of Physics 2005 Meeting
Section: Polymer Physics
Title:
Electrohydrodynamic Convection in SmC* Liquid Crystals
Authors:
Lucian Georgescu, Emil Barna, Cristina Miron, Adriana Andronie
Affiliation:
University of Bucharest, Faculty of Physics, POB MG-11, Romania
E-mail
cmiron_2001@yahoo.com
Keywords:
Freedericks transitions, convective instability, chiral smectic liquid crystals
Abstract:
In chiral smectic liquid crystals (SmC*) a macroscopic polarization exists and SmC* can also prepared as a quasi two dimensional free – standing film similar to free standing smectic A films.
Here we describe a new convective instability and a generalized Freedericks transitions, which both are only possible due to the macroscopic polarization in SmC* and analyzed the liniarized electrohydrodynamics of a freely suspended SmC* liquid crystals film.
For applied DC voltages a spontaneous polarization leads to an increase or decrease of the threshold for electroconvective instabilities, depending on whether the polarization is parallel or anti parallel to the driving field.
For applied AC voltages the well known conductive and dielectric regimes, which are governed by a harmonic movement of all variables at the onset of convection. A new class of solutions, however, moving sub harmonically at the onset, becomes possible due to the polarization.
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