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Abstract
Switching study of an antiferroelectric liquid crystal (S)-4-(1-methylheptyloxycarbonyl)phenyl-4′-(6-pentanoyloxyhex-1-oxy)biphenyl-4-carboxylate (4H6Bi(S)) have been carried out for the planar aligned sample as a function of temperature by the polarization reversal current technique. Switching time (t
S), spontaneous polarization (P
S) and torsional viscosity () of the material have been determined. t
S is found to be in the range 2–4 ms in the ferroelectric (SmC*) phase and 0.4–0.7 ms in the antiferroelectric
phase. Above the critical electric field E
C where the helix unwinds, t
S is found to be inversely proportional to E but P
S is found to be independent of E. P
S lies between 5 and 106 nC cm−2 in the SmC* phase and between 120 and 235 nC cm−2 in the
phase. It obeys the power law
with
nC cm−2,
°C and
. The activation energies calculated from the Arrhenius plot of
are 520 and 41 kJ mol−1 for the SmC* and
phases, respectively.
Acknowledgements
The authors acknowledge the financial support in the form of a research grant provided by the Department of Science & Technology, Government of India (Grant No. SR/S2/CMP–45/2004). One of the authors (Suman Kumari) thanks DST for the fellowship under this research project and acknowledges the discussions with Prof S.L. Srivastava as well as the help rendered by Dr Anil Kumar.
