Dielectric Characterisation of an Orthoconic Antiferroelectric Liquid Crystal Mixture

Abstract

Dielectric properties of the orthoconic smectic liquid crystalline mixture W-129, which presents both antiferroelectric and ferroelectric smectic C phases, have been studied in the frequency range from 10 mHz to 100 kHz in planar aligned cells. Some important relaxation modes were detected in SmCa* and SmC* phases. Dielectric increments, distribution parameters and relaxation frequencies of these modes have been evaluated at different temperatures. From the study of dielectric spectra a great variety of relaxation responses emerges that could indicate the presence of different SmCa* subphases.

Keywords:

• Dielectric spectroscopy
• orthoconic antiferroelectric mixtures
• relaxation modes

Acknowledgments

The authors acknowledge Professor Dabrowski for providing the W-129 liquid crystal, Dr M. Sposato for providing the necessary experimental facilities and for the interesting discussions and Mrs. Francesca Misasi for critical reading of the manuscript.