화학공학소재연구정보센터
Molecular Crystals and Liquid Crystals, Vol.512, 1867-1877, 2009
Effects of Confinement and Electric Field on the Dielectric Behavior of Smectic-C*(alpha) Phase
Dielectric permittivity measurements are carried out to investigate the effects of confinement and electric field on a chiral smectic liquid crystal in the smectic-C*(alpha) (Sm-C*(alpha)) phase for various cell thicknesses. The Sm-A* - Sm-C*(alpha) transition temperature and the temperature range for which the Sm-C*(alpha) phase is stable decrease with decreasing cell thickness. On reducing the cell thickness, the surface-induced mode appears, as a result of the influence of the cell substrates. This increases the dielectric strength of the Sm-C*(alpha) phase. The distribution parameter of the relaxation process, a decreases significantly, and in the case of a thin cell, the decrease observed reflects a wide symmetric distribution of the relaxation process. On increasing the electric field, the dielectric strength decreases and the relaxation frequency increases in the Sm-C*(alpha) phase. These are explained by the 'helical fracture' model, originally proposed for the Sm-C* phase.