Effect of pressure on spontaneous polarization and tilt angle in ferroelectric liquid crystal dobambc

Abstract

Using a thermodynamic model based on the generalized Landau free-energy density expansion, we investigate the influence of hydrostatic pressure on the spontaneous polarization and tilt angle of ferroelectric chiral smectic C (Sm C*) phase near the Sm ASm C* transition in a ferroelectric mesogen DOBAMBC. It is shown that the pressure dependence of the tilt angle, spontaneous polarization and Sm ASm C* transition temperature (Tc) can be described in terms of four pressure-dependent Landau coefficients: two achiral coefficients a and b and two chiral coefficients Λ and d. The pressure dependence of the parameter a is due to the pressure-dependent Tc. With the increasing pressure, the stability of the Sm C* phase decreases. A close agreement between theory and experiment is found. © 2009 World Scientific Publishing Company.