Smectic Polymorphism and Fluctuations in a Polar Liquid-Crystal Binary Mixture

Abstract

High-resolution x-ray diffraction studies have been performed on the polar liquid-crystal binary mixture of octyl- and decyl-oxyphenyl nitrobenxoyloxy benzoate (47.4 mole% DB₈ONO₂ + 52.6% DB₁₀ONO₂). At temperatures below 127 °C this mixture exhibits the phase sequence (with decreasing temperature) smectic-Ad—reentrant nematic N_d—reentrant nematic N₁—smectic-A₁—tilted smectic antiphase smectic- [Ctilde] -smectic-A₂—smectic-C₂. The development of lateral fluid antiphase fluctuations from the partial bilayer fluctuations in the smectic-A₁ phase have been probed and analyzed as well as the transition from the tilted smectic antiphase to the tilted bilayer smectic-C₂ phase that is accompanied by the occurrence of an intermediate smectic-A₂ phase.

Key Words:

• liquid-crystal phase transitions
• calorimetry
• x-ray scattering
• tilted smectic antiphases