Molecular and dynamical properties of a perfluorinated liquid crystal with direct transition from ferroelectric SmC* phase to isotropic phase

One recently synthesized partially fluorinated ferroelectric liquid crystal is investigated by X-ray diffraction, dielectric relaxation spectroscopy and electrooptic techniques. It exhibits only ferroelectric SmC* phase over a broad temperature range and it directly goes to isotropic phase from SmC* phase which is rare in ferroelectric liquid crystals. Tilt angle, measured by X-ray and optical methods, is found to be high. Only Goldstone mode relaxation process is observed. Increase of dielectric strength and critical frequency with temperature has been explained in the light of generalized landau model. No soft mode is observed since the compound directly melts into isotropic phase. It possesses moderate value of spontaneous polarization and the data fitted nicely to mean-field model and reproduced critical temperature within 0.5 degrees. Fitted critical exponent (0.29) suggests that SmC*-I transition is first order which is supported by DSC measurements. Goldstone mode rotational viscosity is found to obey Arrhenius behavior, thermal activation energy was found to be 97.1 kJ mol(-1). Very fast switching is observed under square pulse. The compound induces ferroelectric phase even below room temperature when mixed in a proper host mixture. (C) 2013 Elsevier B.V. All rights reserved.