Bistable switching and electroclinic effect of a low pitch and large spontaneous polarization ferroelectric liquid crystal mixture

Switching time (t(s)), spontaneous polarization (P-s) and torsional bulk viscosity (gamma(t)) in the SmC* phase of a low pitch planar oriented ferroelectric liquid crystal mixture FLC # 252 of thickness 15 mu m have been measured in the temperature range of 25 to 52 degrees C by the polarization reversal method. Optical tilt angle (theta) in the SmC* phase and induced tilt angle (theta(ind)) in the SmA* phase produced by the electroclinic effect have been determined. P-s has been fitted on P-s = 27.32(T-c-T)(0.44) nC/cm(2) below the Curie temperature T-c=51.4 degrees C. P-s is screened by the space charge from 25 to 35 degrees C. t(s) lies in the range of 36 to 2 ms and varies inversely with E above a critical field E-c. The ratio P-s/sin(2) theta (= 512 nC/cm(2)) and the critical field E-c(= 1.20 kV/cm) are almost temperature independent from 25 to 44 degrees C. gamma(t) obeys the Arrhenius relation from 25 to 44 degrees C with an activation energy of 0.36 eV. At room temperature gamma(t) is about 50 times larger than the phason rotational viscosity gamma(phi). The flexoelectric coupling constant C and thermodynamic Landau parameter alpha are determined to be C = 0.33 x 10(8) V/m-rad and alpha = 0.23 x 10(5) N/m(2)-rad(2)-degrees C.