Abstract
We report apparent viscosity in an electric field (ER property) of chiral smectic liquid crystals. Seven smectic liquid-crystalline materials, which have various structures and a different magnitude of spontaneous polarization, were prepared. Their ER properties were measured using a cylindrical rotational viscometer. A decrease in the apparent viscosity of the shear flow in a DC field was observed in the SmC* phase of a mixture composed of 5-nonyl-2-(4-nonyloxyphenyl)pyrimidine and (S)-4-(2-methyloctanoyl)-4'-biphenyl 3-chloro-4-octyloxybenzoate. At the same time, the material was found to be transparent. The ER properties in SmC* phases observed by viscosity measurements are discussed in comparison with the textures depending on the change of the molecular ordering observed by thermal optical microscopy.