Anisotropic Physical Properties

Abstract

The occurrence of a fluid phase in combination with birefringence led to the discovery of liquid crystals. Nowadays the liquid crystalline nature of a given material is still most easily established by the anisotropy of a physical property such as the refractive index. A macroscopic anisotropy is found because the molecular anisotropy related to this property does not average out to zero as is the case in an isotropic phase. Consequently the orientational distribution function and the associated order parameters are an important part of the description. The present chapter can be considered to be an extension of the previous one, where the magnetic susceptibility was discussed as an example of an anisotropic physical property. In the following we shall extend our discussion to the refractive index and the dielectric permittivity, chosen because of their relevance to modern display applications of liquid crystals. This chapter ends with a section on anisotropic transport properties.