Liquid Crystal Phases
The various LC phases (called mesophases) can be characterized by the type of ordering. One can distinguish positional order (whether molecules are arranged in any sort of ordered lattice) and orientational order (whether molecules are mostly pointing in the same direction), and moreover order can be either short-range (only between molecules close to each other) or long-range (extending to larger, sometimes macroscopic, dimensions). Most thermotropic LCs will have an isotropic phase at high temperature. That is that heating will eventually drive them into a conventional liquid phase characterized by random and isotropic molecular ordering (little to no long-range order), and fluid-like flow behavior. Under other conditions (for instance, lower temperature), an LC might inhabit one or more phases with significant anisotropic orientational structure and short-range orientational order while still having an ability to flow.
The ordering of liquid crystalline phases is extensive on the molecular scale. This order extends up to the entire domain size, which may be on the order of micrometers, but usually does not extend to the macroscopic scale as often occurs in classical crystalline solids. However some techniques, such as the use of boundaries or an applied electric field, can be used to enforce a single ordered domain in a macroscopic liquid crystal sample. The ordering in a liquid crystal might extend along only one dimension, with the material being essentially disordered in the other two directions.
Read more about this topic: Liquid Crystal
Famous quotes containing the words liquid, crystal and/or phases:
“Tomorrow night, when Phoebe doth behold
Her silver visage in the watery glass,
Decking with liquid pearl the bladed grass.”
—William Shakespeare (1564–1616)
“I waited alone, in the company of orchids, roses and violets who—like people waiting beside you, but to whom you are unknown—maintained a silence which their individuality of living things rendered more imposing and in their chilly manner received the heat from an incandescent coal fire, preciously placed behind a crystal glass, in a white marble tub where it dropped, from time to time, its dangerous rubies.”
—Marcel Proust (1871–1922)
“This socialism will develop in all its phases until it reaches its own extremes and absurdities. Then once again a cry of denial will break from the titanic chest of the revolutionary minority and again a mortal struggle will begin, in which socialism will play the role of contemporary conservatism and will be overwhelmed in the subsequent revolution, as yet unknown to us.”
—Alexander Herzen (1812–1870)