Liquid
Crystals
Liquid crystalline materials feature structure
intermediate between liquid and crystalline solids. The simplest example of
liquid crystalline material is a solution of rod-like molecules. There are
exists a large number of liquid crystalline phases which are distinguished by
the degree of positional order. The simplest of phases is the nematic phase.
The nematic liquid crystals possess no positional order (the centers of mass of
molecules are uncorrelated like in liquid) but feature orientational order.
Isotropic liquid
Nematic liquid crystal
When viewed with a polarizing-light microscope, nematic liquid crystals exhibit birefringent "textures" that are related to the long- range orientational order in this curious fluid state of matter. (Provided by P. Mather)