Liquid crystal

Liquid crystals are substances that exhibit a phase of matter that has properties between those of a conventional liquid, and those of a solid crystal. For instance, a liquid crystal (LC) may flow like a liquid, but have the molecules in the liquid arranged and oriented in a crystal-like way. There are many different types of LC phase, which can be distinguished based on their different optical properties (such as birefringence). Viewed in a microscope under polarized light illumination, a liquid crystal material will appear to have a distinct texture. Each 'patch' in the texture corresponds to a domain where the LC molecules are oriented in a different direction. Within a domain, however, the molecules are well ordered. Liquid crystal materials may not always be in an LC phase (just as water is not always in the liquid phase: it may also be found in the solid or gas phase). Liquid crystals can be divided into thermotropic and lyotrophic LCs. Thermotropic LCs exhibit a phase transition into the LC phase as temperature is changed, whereas lyotropic LCs exhibit phase transitions as a function of concentration.

References

• {{Book reference | Author=de Gennes, P.G. and Prost, J | Title=he Physics of Liquid Crystals | Publisher=Oxford : Clarendon Press | Year=1993 | ID=ISBN 0198520247}}
• {{Book reference | Author=Chandrasekhar, S. | Title=Liquid Crystals; 2^nd edition | Publisher=Cambridge: Cambridge University Press | Year=1992 | ID=ISBN 0521417473 (hardback) ISBN 052142741X (pbk.)}}
• {{Journal reference issue | Author=Kleinert, H. and Maki, K | Title=Lattice Textures in Cholesteric Liquid Crystals | Journal=Fortschritte Physik | Volume=29 | Issue=1 | Year=1981 | Pages=}}
• {{Book reference | Author=Collings, P.J. and Hird, M | Title=Introduction to Liquid Crystals | Publisher=Bristol, PA : Taylor & Francis | Year=1997 | ID=ISBN 0748406433 (hardback) ISBN 074840483X (pbk.)}}