Thermodynamic and bias field characterization of a quickly operating antiferroelectric liquid crystal

Dielectric relaxation spectroscopy of a quickly operating antiferroelectric liquid crystal (W-204D) has been carried out under the influence of bias electric field in the frequency range of 20 Hz-20 MHz in planar aligned cells. W-204D represents both antiferroelectric (SmCA*) and ferroelectric (SmC*) phases. The temperature dependent dielectric investigation has been studied to explore its effect on the dielectric parameters, where a couple of relaxation modes were observed in SmC* phase. Dielectric characterization reveals a Goldstone mode around 32.595 kHz and a Soft mode at ~ 100 kHz in the SmC* phase. To study the collective relaxation processes between these two modes W-204D was examined under the influence of DC bias electric field. Due to helical unwinding at 30 V bias Goldstone mode get totally suppressed. Experimental data was modeled by Debye and Cole-Cole method indicated that the relaxations are of non-Debye type. Dielectric variations, distribution parameters and relaxation frequencies of these modes have been calculated at various temperatures.