What are the nematic liquids?

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. The extent of the change in polarization depends on the intensity of an applied electric field .

What is nematic phase of liquid crystal?

The nematic liquid crystal phase is characterized by molecules that have no positional order but tend to point in the same direction (along the director). In the following diagram, notice that the molecules point vertically but are arranged with no particular order.

What is nematic liquid crystal with example?

Nematic Liquid Crystals They have characteristic textures when viewed under cross polarized light microscope. These materials are birefringent and allowing light with different polarizations to go through at different speeds. Two examples are cyanobiphenyls and another with rigid and mantle group in the system.

What is liquid crystalline phase?

A liquid crystal is a thermodynamic stable phase characterized by anisotropy of properties without the existence of a three-dimensional crystal lattice, generally lying in the temperature range between the solid and isotropic liquid phase, hence the term mesophase.

What is a nematic phase?

The simplest liquid crystal phase is called the nematic phase (N). It is characterized by a high degree of long range orientational order but no translational order. Molecules in a nematic phase spontaneously order with their (for calamitic molecules) long axes roughly parallel.

What is nematic and smectic liquid crystals?

Nematic liquid crystals have no ordered structure of molecules, and smectic liquid crystals have a layered molecular structure, whereas cholesteric liquid crystals have the molecules in a twisted and chiral arrangement.

What is nematic in chemistry?

: of, relating to, or being the phase of a liquid crystal characterized by arrangement of the long axes of the molecules in parallel lines but not layers — compare cholesteric, smectic.

Where is nematic liquid crystal used?

Hence, biaxial nematic liquid crystals can be successfully used for electro-optic switching or to control birefringence, considering negative dielectric anisotropy or lower viscosities associated with E-field reorientation of the transverse director about an aligned director n.

Where are liquid crystals used?

Liquid crystals are everywhere. They are used in all kinds of display devices including computer monitors and laptop screens, TVs, clocks, visors, and navigation systems. Each pixel in a monitor is an assembly of liquid crystals controlled by its own electromagnetic field.

What is smectic and nematic liquid crystal?

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 does liquid crystal look like?

Liquid crystals, however, change into a cloudy liquid very different from liquids like water, alcohol, or cooking oil. At slightly higher temperatures, the cloudiness disappears, and they look much like any other liquid. When the liquid crystal is a solid, its molecules are lined up parallel to one another.

What are discotic nematic liquid crystals?

The discotic nematic liquid crystals were discovered during the time when its calamitic counterpart was revolutionizing the LCD technology. Quite naturally, it immediately caught the attention for the evaluation of various display parameters and development of novel alignment techniques, then, being a new probable candidate for LCD devices.

What type of mesophase is nematic?

The nematic mesophase is the most diverse mesophase occurring in calamitic (rod-like) molecules but not common in discotic (disc-like) molecules. It occurs in both thermotropic and lyotropic liquid crystals and appears in monomeric and polymeric liquid crystals.

One of the most common LC phases is the nematic. The word nematic comes from the Greek νήμα ( Greek: nema ), which means “thread”. This term originates from the thread-like topological defects observed in nematics, which are formally called ‘ disclinations ‘. Nematics also exhibit so-called “hedgehog” topological defects.

What is the difference between calamitic nematic and discotic nematic LCDs?

The uniaxial calamitic nematic LCs are the active switching components of present LCD technology, whereas the uniaxial discotic nematic counterparts act as optical compensation films to widen the viewing angle and to increase the contrast ratio of LCDs.