Dielectric relaxation study of a H shaped liquid crystal dimer

Abstract

The present article reports dielectric relaxation study of an unusual shaped liquid crystal dimer (H shape) in the temperature range 40–85°C. The study of this liquid crystal dimer is important due to the presence of azo central linkage, which is photosensitive. The dielectric relaxation study indicates coupling between the electric field and the liquid crystal molecule of H shaped dimer. Various dielectric properties for this liquid crystal dimer are quite different from the conventional liquid crystals. The dielectric relaxation observed in the smectic phase is due to the reorientation of molecule along the director in the presence of an applied electric field. The temperature dependence of the dielectric parameters, such as relaxation frequency, relaxation strength and distribution parameter have been evaluated for this liquid crystal dimer for both planar as well as homeotropically aligned cell and then compared. The Cole–Cole equation has been used to evaluate the aforementioned parameters.

Keywords:

• relaxation frequency
• dielectric parameters
• liquid crystal dimer

Acknowledgements

One of the authors (AKM) is thankful to UGC, New Delhi for the II year grant of Dr. D.S. Kothari Post Doctoral Fellowship No. F.4.2/2006 (BSR)-13-234/2008(BSR).