Influence of an electric field on phase transitions in ferroelectric liquid crystals

Abstract

Abstract The transition temperatures between various smectic liquid crystal phases in chiral (ferroelectric) compounds have been determined as a function of an applied DC electric field. We find that SG-SA and SG-SC transitions show a field-induced temperature shift proportional to the applied field strength similar to the already known behaviour of first order SC-SA transitions. In contrast, for the nonferroelectric SB-SA and SE-SB transitions no effect of the electric field is observed. The field-induced temperature shift is compared with the temperature shift occurring in chiral-racemic systems of the same compounds (see Bahr, Ch., Heppke, G., and Sabaschus, B., 1991, Liq. Crystals, 9, 31). Using Landau theory we derive a simple relation between these two quantities.