Observation of scaling behaviour of dielectric relaxation in ferroelectric liquid crystals

Abstract

The temperature (25–120°C) and frequency (10 Hz–1 MHz) dependent dielectric relaxation spectra of different ferroelectric liquid crystals are found to show interesting scaling behaviour. Considering relaxation frequency (ν_max) as the scaling frequency, the imaginary part of the dielectric constants (ε″) of the ferroelectric liquid crystals are found to follow the universal scaling formula

, i.e. when (ε″/ε″_max) is plotted as a function of (f/ν_max), the scaling behaviour of a ferroelectric liquid crystal can be represented by a single master curve irrespective of film thickness, bias field and temperature; ε″_max is the maximum value of ε″ at the frequency ν_max and m is a parameter ∼1.

Acknowledgements

The authors are grateful to the CSIR Government of India for a research grant and fellowship to carry out this project. The authors are also grateful to the AvH Foundation, Germany, and Prof. W. Haase for providing the instruments for measuring dielectric relaxation of the liquid crystals.