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.