• K K Raina

      Articles written in Pramana – Journal of Physics

    • Observation of relaxation modes in room temperature ferroelectric liquid crystal mixtures

      K K Raina Arvind K Gathania Buta Singh

      More Details Abstract Fulltext PDF

      The dielectric measurements in SmC* and SmA phases of a room temperature ferroelectric liquid crystal mixture FLC-6980 in the cells of different thickness in planer alignment have been carried out in the frequency range 100 Hz to 1 MHz. A relaxation mode (called NRM) whose dielectric increment is less than the Goldstone mode has been observed in the SmC* phase. This mode appears due to the surface effect. Goldstone mode and the soft mode was observable in the vicinity of SmC*-SmA transition temperature (TC*A). The dielectric parameters of the Goldstone mode, new mode and the soft mode have been studied as a function of frequency and temperature. The calculated values for fNRM, δεNRM and distribution parameter αNRM are found to be 325 kHz, 6 and 0.156 for 5μm thick planer cell at 37°C. It is seen that in the vicinity of theTC*A, soft mode obeys the Curie-Weiss law given by mean field theory. The results have been compared with materials of large spontaneous polarization.

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