POLAR PHASES IN CHIRAL THIOBENZOATE LIQUID-CRYSTALS

By dielectric measurements, the temperature scan method and studies of optical hysteresis loops, the phase sequences have been elucidated fo r two new compounds from a series of homologues containing a thiobenzo ate group with a fluoro substituent in the first benzene ring (denoted nFHTBBM7). Both compounds (n = 11 and n = 12) exhibit antiferroelect ric (S-CA) ferroelectric (S-C*) and several ferrielectric (S-CFI) pha ses, as well as the (S-C alpha) phase. Also, in the compound 11FHTBBM 7, a metastable ferrielectric phase may appear in the temperature ran ge of the antiferroelectric phase. The dielectric relaxation study rev ealed contributions to the dielectric constant from several modes dete cted in the temperature range studied. The properties of the relaxatio n modes and the phase transition sequences of the two compounds have b een compared with those of the homologues with n = 9 and n = 10 studie d previously.