A novel sequence of electric switching in bent core structure

Prasad N. Bapat, D. S. Shankar Rao, S. Krishna Prasad, U. S. Hiremath, and C. V. Yelamaggad,
Phys. Rev. E, 87, 042504 (2013)

We report the effect of applied pressure on the dielectric properties of the B2 phase of a bent-core liquid crystal. The study, the first of its kind on bent core banana-shaped molecules shows that while the dielectric anisotropy hardly varies with pressure, the relaxation parameters associated with the rotation around the long axes of the molecules are significantly influenced. These studies also bring out the fact there are additional phases between the B2 phase and the true crystalline solid. Indeed, the existence of another variant of the B2 phase (labelled B2′), is revealed only in dielectric studies but not seen in Xray and calorimetric measurements. Employing the dependence of the relaxation frequency along isobaric as well as isothermal paths, different activation parameters are determined and their behaviour is compared with those of rod-like systems. The influence of DC bias on the dielectric behaviour obtained at atmospheric pressure is also presented, which exhibits features similar to chiral antiferroelectric smectics, and further shows an additional relaxation over a small window of DC voltages.