Determination of the Temperature Dependent Smectic C Biaxial Permittivity Tensor and Elastic Constants

Abstract

The direct measurement of the smectic C bend (B₁) and splay (B₂) elastic constants and the three permittivities ε₁, ε₂ and ε₃ for the commercial material SCE8R is described. A new technique has been employed in which some of the assumptions inherent in previous measurements^[1,2] have been removed and the inaccuracies have been reduced. This involves fitting the a.c. field dependence of the permittivity in the surface stabilised chevron (C2U) geometry using continuum modelling. Data from the fitting process is combined with measurements of the homeotropic permittivity and electro-optical measurements of the layer tilt angle and smectic cone angle.

Key Words:

• Smectic C Liquid Crystals
• Dielectric Permittivity
• Elastic Constant