Selective reflection of light in glassforming ternary liquid crystalline mixtures

Abstract

Two ternary liquid crystalline mixtures are formulated and investigated by differential scanning calorimetry, polarizing optical microscopy, X-ray diffraction, and broadband dielectric spectroscopy. Paraelectric smectic A*, ferroelectric smectic C*, and antiferroelectric smectic C${}_A$* phases are detected. The glass of the smectic C${}_A$* phase is formed at moderate cooling rates. Vitrification prevents the approaching transition to a hexatic smectic phase. One mixture shows a strong thermochromic effect in the smectic C${}_A$* phase and selectively reflects blue light in the glassy state. Both mixtures reflect either green or red light in the smectic C* phase, depending on temperature treatment: whether the sample is cooled or heated, or at which rate the temperature changes.

one co-author added, experimental results extended by X-ray diffraction measurements as a function of temperature