Behaviour of the Electroclinic Effect in a Homologous Series of Ferroelectric Liquid Crystals

The electroclinic effect, a kind of inverse piezoelectric effect, is studied in the smectic A phase of several homologous liquid crystal compounds. The induced tilt/applied field ratio θ/E is found to increase with increasing length of the alkyl chain whereas the coupling constant k = Pθ/θ between induced tilt and induced polarization decreases with increasing chain length. The measurements allow the determination of the tilt controlling susceptibility coefficient of the smectic A phase, which is found to decrease considerably with increasing alkyl chain length.