Kinetics of the transition between ferroelectric and antiferroelectric states in liquid-crystalline mixtures

Investigations of a mixture with induced antiferroelectric phase are descri bed. This mixture exhibits large thermal hysteresis of the transition betwe en ferroelectric and antiferroelectric phases, which was demonstrated using dielectric and optical methods. The kinetics of the transition from the fe rroelectric to the antiferroelectric state was extremely slow - its time co nstant ranged from few minutes to many hours, depending on temperature. The rate of transition formally obeys the Avrami equation describing the kinet ics of phase transitions from a supercooled state. However, the remarkably small exponent suggests, that the Avrami model is not suitable for descript ion of the investigated transition. The coexistence of ferroelectric and an tiferroelectric states was noticed in a broad temperature range. In the sam e range the V-shaped switching was observed. The observed phenomena: hyster esis, slow kinetics and threshold-less switching are probably caused by com petition of ferroelectric and antiferroelectric interactions acting between smectic layers.