Experimental Studies on Phase Transitions in an Antiferroelectric Liquid Crystal

The effect of optical purity on the antiferroelectric phase transition and the field-induced ferroelectric phase transition in Sm C A * were studied by means of dielectric measurements and observations of D - E hysteresis loops. The Curie-Weiss law was found to hold in Sm A and the Curie-Weiss constant to increase as the optical purity is reduced. Three types of D - E curves were obtained in the Sm C A * phase. It was found that a double hysteresis loop changed into a single one at high frequencies. The results obtained are discussed on the basis of a phenomenological theory.