Relaxation processes in the ferrielectric and alpha phases of antiferroelectric liquid crystals
Bibonne, F.; Parneix, J. P.; Nguyen, H. T.; Bibonne F.; Laboratoire de Physique des Interactions Ondes-Matière ( UMR CNRS 5501), ENSCPB, avenue Pey-Berland, BP 108, 33 402 Talence Cedex, France; Parneix J. P.; Laboratoire de Physique des Interactions Ondes-Matière ( UMR CNRS 5501), ENSCPB, avenue Pey-Berland, BP 108, 33 402 Talence Cedex, France; Nguyen H. T.; Centre de Recherche Paul Pascal (UPR CNRS 8641), avenue A. Schweitzer, 33 600 Pessac Cedex, France
Журнал:
The European Physical Journal Applied Physics
Дата:
1998
Аннотация:
Dielectric measurements of a new antiferroelectric liquid crystal series exhibiting different phase sequences have been carried out as a function of frequency from 10 Hz to 10 MHz. Structural properties of S<sub>C<sub>α</sub> </sub> <sup>*</sup> and ferrielectric S<sub>C<sub>FI</sub> </sub> <sup>*</sup> phases were discussed on the basis of the experimental results of temperature and dc bias field dependencies of the dielectric modes. Besides the soft mode observed around the S<sub>A</sub>−S<sub>C<sub>α</sub> </sub> <sup>*</sup> phase transition, a Goldstone mode was detected in the S<sub>C<sub>α</sub> </sub> <sup>*</sup> phase indicating a helicoidal structure with small pitch values. In agreement with a bilayer ordering model, the dielectric absorption in the S<sub>C<sub>FI</sub> </sub> <sup>*</sup> phase was splitted up into two contributions: one related to a Goldstone mode and the other to an azimuthal antiphase mode.
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