STUDIES ON THE DIELECTRIC BEHAVIOR OF TGBA PHASE

This paper reports on the dielectric and electro optical studies of tw o ferroelectric liquid crystals having TGBA phases. Complex dielectric permittivities have been measured in planar aligned cells in the freq uency range of 10 Hz to 10 MHz. Bias dependent measurement were perfor med in the S-C+ and in the TGBA phase. In the S-C phase three differe nt collective relaxation processes, the Goldstone mode, the Domain mod e 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 bia s field whereas the Soft mode in the other compound was observed only after the application of a bias field. The dielectric results shows th at bias induced alignment once achieved does not change even after swi tching off the bias voltage. It has been observed that the dielectric characteristics of TGBA phases can be similar to that of normal smecti c A; or cholesteric phases, depending upon the temperature interval o f the TGBA-phase. The results have been discussed.