Investigation of Collective Relaxation Modes of (S)-(+)-4′-[4-(1-methylheptyloxycarbonyl)] biphenyl 4-[3-(octanoyloxy)prop-1-oxy]benzoate by Dielectric Spectroscopy

Abstract

In the present work, we are reporting thermal, optical and dielectric properties of (S)-(+)-4′-[4-(1-methylheptyloxycarbonyl)] biphenyl 4-[3-(octanoyloxy)prop-1-oxy]benzoate. This compound possesses Iso- SmA*– SmC*_α – SmC* –SmC*_γ–SmC*_A–Cr phase sequences upon cooling. Dielectric properties of this compound have been investigated under planar anchoring of samples in the frequency range of 1 Hz to 10 MHz with temperature and bias electric filed. Various relaxation modes active in SmC* sub-phases have been observed and their parameters have been analyzed by fitting theoretical Cole-Cole equations. In the SmA* phase, soft mode relaxation has been observed. In chiral tilted smectic subphases (viz. SmC*_α, SmC*, SmC*_γ) two relaxation modes are observed in different frequency ranges. In the SmC*_A phase two modes have been observed due to antiferroelectric ordering.

Acknowledgments

Authors wish to thank Department of Science and Technology, New Delhi, India for financial assistance under a project No. SR/FTP/PS/14/2005. The authors sincerely thank to Prof. Pradip Kumar, Head, Physics Department, University of Allahabad, Allahabad-211002 and Prof. I. M. L. Das, Physics Department, University of Allahabad, Allahabad-211002 for providing dielectric measurement facility.