Antiferroelectric liquid crystals studied by different methods

Liquid crystalline substances, exhibiting ferroelectric and antiferroelectr ic phases, have been studied by means of frequency domain dielectric spectr oscopy as well as electrooptic and DSC calorimetry methods. Strong Goldston e mode in the ferroelectric SmC* phase and soft mode in the paraelectric Sm A* 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 rev ersal current spectrum exhibits one peak in the ferroelectric SmC* phase wh ereas the antiferroelectric phase shows two separated peaks. Spontaneous po larization has been evaluated as a function of temperature.