Liquid crystals

Liquid crystals (LCs) are a state of matter that has properties between those of a conventional liquid and those of a solid crystal[1]. For instance, an LC may flow like a liquid, but its molecules may be oriented in a crystal-like way. There are many different types of LC phases, which can be distinguished by their different optical properties (such as birefringence). When viewed under a microscope using a polarized light source, different liquid crystal phases will appear to have distinct textures. The contrasting areas in the textures correspond to domains where the LC molecules are oriented in different directions. Within a domain, however, the molecules are well ordered. LC materials may not always be in an LC phase (just as water may turn into ice or steam). Liquid crystals can be divided into thermotropic, lyotropic and metallotropic phases. Thermotropic and lyotropic LCs consist of organic molecules. Thermotropic LCs exhibit a phase transition into the LC phase as temperature is changed. Lyotropic LCs exhibit phase transitions as a function of both temperature and concentration of the LC molecules in a solvent (typically water). Metallotropic LCs are composed of both organic and inorganic molecules; their LC transition depends not only on temperature and concentration, but also on the inorganic-organic composition ratio. Examples of liquid crystals can be found both in the natural world and in technological applications. Most modern electronic displays are liquid crystal based. Lyotropic liquid-crystalline phases are abundant in living systems. For example, many proteins and cell membranes are LCs. Other well-known LC examples are solutions of soap and various related detergents, as well as tobacco mosaic virus.

Further information:

1. Liquid Crystals, S. Chandrasekhar, Cambridge University Press: 1994
2. T. J. Sluckin, D. A. Dunmur and H. Stegemeyer (2004). Crystals that Flow. Taylor and Francis.
3. Gennes, P.G. and Prost, J (1993). The Physics of Liquid Crystals. Oxford: Clarendon Press.
4. Chandrasekhar, S. (1992). Liquid Crystals (2nd ed.). Cambridge: Cambridge University Press.
5. Dierking (2003). Textures of Liquid Crystals. Weinheim: Wiley-VCH.
6. Shao, Y.; Zerda, T. W. (1998). "Phase Transitions of Liquid Crystal PAA in Confined Geometries". Journal of Physical Chemistry B 102 (18): 3387–3394.
7. L. A. Madsen, T. J. Dingemans, M. Nakata, and E. T. Samulski (2004). "Thermotropic Biaxial Nematic Liquid Crystals". Phys. Rev. Lett. 92: 145505.
8. Joseph A. Castellano (2005). Liquid Gold: The Story of Liquid Crystal Displays and the Creation of an Industry. World Scientific Publishing.
9. Harry J. Coles, Mikhail N. Pivnenko (2005). "Liquid crystal 'blue phases' with a wide temperature range". Nature 436: 997–1000.
10. Мальцев П. П., и др. «Нанотехнологии. Наноматериалы. Наносистемная техника», Москва, изд. Техносфера, 2008 г., 430 с.
11. Article Liquid crystals from Wikipedia, the Free Enciclopedia. Available under the license Creative Commons Attribution-Share Alike.

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