Antiferroelectric liquid crystals studied by different methods

Liquid crystalline substances, exhibiting ferroelectric and antiferroelectric phases, have been studied by means of frequency domain dielectric spectroscopy as well as electrooptic and DSC calorimetry methods. Strong Goldstone mode in the ferroelectric SmC* phase and soft mode in the paraelectric SmA* phase have been revealed. In the antiferroelectric phase two dielectric relaxation modes, showing temperature independent dielectric increments and relaxation frequencies, have been observed. It has been found that the reversal current spectrum exhibits one peak in the ferroelectric SmC* phase whereas the antiferroelectric phase shows two separated peaks. Spontaneous polarization has been evaluated as a function of temperature.