Low frequency dielectric relaxation, spontaneous polarization, optical tilt angle and response time investigations in a flourinated ferroelectric liquid crystal, N125F2(R*)

Experimental investigations of thermal microscopy, low frequency dielectric relaxation, spontaneous polarization P s (T), optical tilt angleθ(T) and response timesτ s (T) are carried out in a fluorinated ferroelectric liquid crystal, N125F2(R) exhibiting smectic-A and smectic-Cphases. Dielectric loss in the smectic-A phase exhibits single Debye's relaxation in the MHz region. The smectic-Cphase exhibits two relaxations, viz., a Goldstone mode at500 Hz and another at a much higher frequency,5 MHz. The Arrhenius shift of Smectic-A relaxation frequency (f R ) gives an activation energy of 1.5 eV. The influence of temperature and applied voltage on the smectic-CGoldstone mode relaxation is studied. In the smectic-Chigh frequency relaxation mode, the relaxation frequency (relevant to the tilt) is found to increase with decreasing temperature. The temperature variation of the reciprocal of the dielectric strength (1/Δ s ) above the smectic-A - smectic-Cphase transition qualitatively supports the Curie-Weiss law. Temperature variation of primary (tilt) and secondary (P s ) order parameters are presented. The temperature variation ofτ s in the smectic-Cphase studied through square wave technique is presented. The influence of fluorine atoms on the rigid core part of the present ferroelectric liquid crystal on the physical properties exhibited in it's smectic-Cphase is discussed.