The phase transition in an antiferroelectric liquid crystal(CS-4001) was studied by polarization reversal current, I-E hysteresis loops and dielectric measurements.
Dielectric measurements as a function of d. c. bias field and a. c. probe frequency were made in $SmC^*_A$ phase of CS-4001 compound to study the field induced transition from antiferroelectric to the ferroelectric phase. Two dielectric relaxation peaks observed in the concerned region of the field induced transition were analyzed to the formula of modified Debye relaxator and the Landau free energy functional theory of Orihara and Ishibashi to derive the dielectric relaxation frequencies and the threshold electric fields associated with the transition.
Polarization reversal current was studied at various driving frequencies from 1Hz to 100 Hz for a 1.6μm thin sample of CS-4001 at 40℃. Two peaks during half period were observed and one of them disappeared with increasing the driving frequency. Polarization reversal current also measured to obtain the field induced polarization as a function of the field strength. All of these measurements confirm that the field induced phase transition undergoes from the antiferroelectric to the ferroelectric phase.