What is cholesteric liquid crystal phase?
A cholesteric liquid crystal display (ChLCD) is a display containing a liquid crystal with a helical structure and which is therefore chiral. Examples of compounds known to form cholesteric phases are hydroxypropyl cellulose and cholesteryl benzoate.
What are cholesteric liquid crystals used for?
Cholesteric liquid-crystal laser can be used as an optic fiber-based temperature sensor[4]. Cholesteric Liquid Crystals can be used in Flexible mirror less Laser[2]. Ferroelectric Liquid Crystal can be used in Electrically tunable waveguide Laser. studied ones are thermotropics, polymerics, and lyotropics.
What is a cholesteric phase?
[kə′les·tə·rik ‚fāz] (physical chemistry) A form of the nematic phase of a liquid crystal in which the molecules are spiral.
What is the difference between nematic smectic and cholesteric liquid crystals?
The key difference between nematic smectic and cholesteric liquid crystals is that nematic liquid crystals have no ordered structure of molecules, and smectic liquid crystals have a layered molecular structure, whereas cholesteric liquid crystals have molecules in a twisted and chiral arrangement.
What is the meaning of cholesteric?
: of, relating to, or being the phase of a liquid crystal characterized by arrangement of molecules in layers with the long molecular axes parallel to one another in the plane of each layer and incrementally displaced in successive layers to give helical stacking — compare nematic, smectic.
What are cholesteric liquid crystals How do they work and what are they used for?
Cholesteric liquid crystals (LCs) responsive to external stimuli, such as temperature or light, can be used for color switching or tuning through the change in the cholesteric pitch.
Why are cholesteric liquid crystals Coloured?
The molecules in a cholesteric liquid crystal self-organize to form a helically ordered structure. The origin of the interfer- ence color of the liquid crystal is this helical structure whose pitch determines the wavelength of the selectively reflected light.
What is nematic liquid crystal?
A nematic liquid crystal is a transparent or translucent liquid that causes the polarization (that is, the focusing in a plane) of light waves to change as the waves pass through the liquid. Nematic liquid crystals are used in twisted nematic display s, the most common form of liquid crystal display .
What is the difference between thermotropic and lyotropic liquid crystals?
Thermotropic liquid crystalline phases are formed by a change of temperature, whereas lyotropic phases are formed when mixed with aqueous phase. The phase transitions of thermotropic liquid crystal are temperature-dependent, while those of lyotropic liquid crystals depend on both temperature and concentration [5].
What is smectic liquid crystal?
A “liquid crystal”- (LC) is an organic compound whose molecules align themselves with an applied electric field. Smectic liquid crystals consist of flat layers of cigar-shaped molecules with their long axes oriented perpendicularly to the plane of the layer.
What is a nematic liquid crystal?
Why use nematic liquid crystals?
Nematics have fluidity similar to that of ordinary (isotropic) liquids but they can be easily aligned by an external magnetic or electric field. Aligned nematics have the optical properties of uniaxial crystals and this makes them extremely useful in liquid-crystal displays (LCD).