Wednesday, 17 July 2024

Novel 2D-solid to 1D- solid transition; Columnar–calamitic phase sequence

D. S. Shankar Rao, M. Vijay Kumar, S. Krishna Prasad, U. S. Hiremath, M. Sarvamangala and S. Basavaraja,
J. Mater. Chem. C, 1, 7488 (2013)

Novel 2D solid to 1D solid transition

We describe here X-ray, electrical switching and dielectric measurements on a binary system comprising achiral bent core and chiral rod-like components. While the pure bent core compound exhibits a single mesophase, namely, the B2 phase, the rod-like compound shows smectic A (SmA) and smectic C* (SmC*) mesophases. A particular mixture, studied in detail here, presents a novel sequence of three columnar type B1 phases, SmA – B1OPAF1 – B1OPAF2 – B1TPAF – Sm C* phase, as the sample is cooled, where the subscripts O, T, P, F and AF indicating, respectively, orthogonal, tilted, polar, ferroelectric and antiferroelectric property, with the B1 phases being of the B1rev type. This phase sequence is established by high resolution Xray diffraction, electrical switching and dielectric measurements, supplemented by texture observations under a polarizing optical microscope.