Dielectric and electro-optical response of a room temperature tri-component antiferroelectric mixture

Frequency- and temperature-dependent dielectric and switching parameters of a room temperature tri-component antiferroelectric liquid crystal mixture W-287 have been determined. Dielectric, optical texture and thermodynamic studies show wide room temperature range antiferroelectric SmC*(a) (91.1 degrees C to<-25 degrees C) phase in addition to high temperature paraelectric SmA* (2.6 degrees C) and ferroelectric SmC* (4.4 degrees C) phases. The dielectric studies carried out in the frequency range of 1-35MHz under planar anchoring condition of the molecules show five different relaxation modes appearing in the SmA*, SmC* and SmC*(a) phases. Using Curie-Weiss law fit, ferroelectric SmC* to paraelectric SmA* transition temperature has been found to be 91.8 degrees C. The dielectric response of SmC*(a) phase exhibits unusually three relaxation modes due to collective as well as individual molecular processes in addition to phason mode in the SmC* phase and amplitudon mode in the SmA* phase. Spontaneous polarisation, switching time and rotational viscosity have also been determined. The maximum value of P-S is 300 nC/cm(2), whereas viscosity is moderate. Switching time is of the order of few milli seconds.