Switching and characteristic dielectric parameters of a room temperature antiferroelectric liquid crystal mixture

摘要

The switching and dielectric properties of a room temperature bicomponent antiferroelectric liquid crystal mixture have been investigated as a function of temperature and frequency. Thermodynamic, optical texture, and dielectric studies carried out on the mixture show the phase sequence of Cr←(12.0℃)→SmI_A~*←(29.1℃)→SmC_A~*←(91.5℃)→SmC~*←(92.9℃)→SmA~*rn←(106.7℃)→Iso. Spontaneous polarization (P_s), switching time (t_s), and torsional bulk viscosity (γ_φ) have been determined by using polarization reversal method. Dielectric spectroscopy of the mixture in the frequency range of 0.1 Hz-10 MHz reveals, eight different modes of relaxation in the paraelectric SmA~*, ferroelectric SmC~*, antiferroelectric SmC_A~* and SmI_A~* phases. Origins of these modes have been identified with the help of frequency, temperature, and bias electric field dependence of various dielectric parameters.