Accurate determination of the temperature and frequency dependent smectic C biaxial permittivity tensor

Abstract

The temperature and frequency dependent smectic C bend (B1) and splay (B2) elastic constants and permittivities ε1, ε2, and ε3 have been measured directly for a commercial smectic C liquid crystal mixture. This has been achieved using continuum modelling to fit the ac field dependence of the permittivity in the C2U chevron geometry. The fitting procedure also makes use of measured values for the homeotropic permittivity, the layer tilt angle, and smectic cone angle. This approach removes many of the assumptions which were inherent in previous measurements giving improved accuracy in the results.