Electric Field Induced Smectic A to Smectic C Transition in Ferroelectric Liquid Crystals

Abstract

The influence of an electric field on the SmC*-SmA transition of two new ferroelectric liquid crystals is investigated. At temperatures just above the SmC*-SmA transition double hysteresis loops are observed similar to that known for solid Cerroelectrics indicating a field induced first order transition to the ferroelectric phase. The first order character of the SmC* -SmA transition of the two compounds under investigation is supported by DSC and tilt angle measurements. With field strength of about 50 kV/ cm the transition temperature is enhanced by 1 K. The shift of the SmC*-SmA transition temperature, which is found to vary linearly with applied field strength, can be calculated by simple thermodynamic arguments.