Dielectric and Optical Properties of Nematic ODBP-Ph-C7

Thermotropic biaxial nematic liquid crystals are promising for application in fast switching electro-optical devices.$^{1}$ In the present work, we study the optical and dielectric properties of the nematic phase of thermotropic LC material 4,4'(1,3,4{\-}oxadiazole{\-}2,5{\-}diyl)~di{\-}$p${\-}heptylbenzoate (ODBP-Ph-C7) with boomerang-like molecules, reported to exhibit the biaxial nematic phase$^{2}$. We study ODBP-Ph C7 in well-aligned ``monocrystalline'' states. The experiments show unusual optical and dielectric properties of the material, such as high dielectric permittivity and dielectric relaxation time that increases with temperature. We also analyze defect structures formed by ODBP-Ph- C7 in different geometries of confinement and boundary conditions. $^{1 }$G. R. Luckhurst, Thin Solid Films \textbf{393}, 40 (2001); $^{2}$ B. R. Acharya, A. Primak, T.J. Dingemans, E.T. Samulski and S. Kumar, Pramana J.Phys. \textbf{61}, 231 (2003).