Frustrated Smectic Phase Appearing as Transitional State between Single-Layer and Antiferroelectric Bilayer Smectic Phases in Binary Mixtures of Dimeric Compounds

摘要

Twin dimers, mOAM5AMOm, form characteristic smectic phases, single-layer SmCA~s and antiferroelectric bilayer SmCA~b phases. Structural transformation from SmCA~s to SmCA~b was examined in two series of binary mixtures of 8OAM5AMO8/4OAM5AMO4 and 8OAM5AMO8/16OAM5AMO16. In this transformation, the frustrated SmCA~f with density modulation along the layer is formed and the size of modulation increases from 50 to 250 A with variations in mixture contents from an edge near SmCA~s to another edge near SmCA~b. From polymorphisms shown by some mixtures, it was found that SmCA~s and SmCA~b are located at high-temperature and low-temperature edges, respectively, and that the SmCA~f phase is set between them.