Studies on the dielectric behaviour of TGBA phase

Abstract

This paper reports on the dielectric and electro optical studies of two ferroelectric liquid crystals having TGBA phases. Complex dielectric permittivities have been measured in planar aligned cells in the frequency range of 10 Hz to 10 MHz. Bias dependent measurement were performed in the S*c and in the TGBA phase. In the S*c phase three different collective relaxation processes, the Goldstone mode, the Domain mode and the Soft mode were detected for both the substances. In the TGBA phase Soft mode has been observed in one of the compounds without bias field whereas the Soft mode in the other compound was observed only after the application of a bias field. The dielectric results shows that bias induced alignment once achieved does not change even after switching off the bias voltage. It has been observed that the dielectric characteristics of TGBA phases can be similar to that of normal smectic A*; or cholesteric phases, depending upon the temperature interval of the TGBA-phase. The results have been discussed.