KINETICS OF THE TRANSITION BETWEEN FERROELECTRIC AND ANTIFERROELECTRIC STATES IN LIQUID-CRYSTALLINE MIXTURES

Abstract

Investigations of a mixture with induced antiferroelectric phase are described. This mixture exhibits large thermal hysteresis of the transition between ferroelectric and antiferroelectric phases, which was demonstrated using dielectric and optical methods. The kinetics of the transition from the ferroelectric to the antiferroelectric state was extremely slow — its time constant ranged from few minutes to many hours, depending on temperature. The rate of transition formally obeys the Avrami equation describing the kinetics of phase transitions from a supercooled state. However, the remarkably small exponent suggests, that the Avrami model is not suitable for description of the investigated transition. The coexistence of ferroelectric and antiferroelectric states was noticed in a broad temperature range. In the same range the V-shaped switching was observed. The observed phenomena: hysteresis, slow kinetics and threshold-less switching are probably caused by competition of ferroelectric and antiferroelectric interactions acting between smectic layers.