ABSTRACT
The property of liquid crystals that distinguishes them from liquids is the small degree of order among the molecules. Solids either can be isotropic or anisotropic, depending on the molecules occupying lattice sites and the crystal lattice itself. Tensor quantities are so important in the description of both the properties and orientational order of liquid crystals that it is important to understand them fully. The anisotropy manifests itself in the elastic, electric, magnetic, and optical properties of a material, in that measurements of an elastic modulus, dielectric constant, magnetic susceptibility, or index of refraction give different results depending on the direction along which it is measured. Because liquid crystals are fluids, they also show anisotropy in their flow behaviour. The anisotropy of a macroscopic phase originates with the molecular anisotropy on a microscopic scale. X-ray diffraction has been the most useful technique in investigating the microscopic structure of liquid crystals. Director configurations around a disclination must minimise the free energy.
