What is a smectic phase?

What is a smectic phase?

In the simplest smectic phase, the smectic-A (SmA) phase, the molecules order into layers, with the layer normal parallel to the director. Here the molecules form a layer structure but the long axes of the molecules, and hence the director, lies at an angle to the layer normal, as shown in Fig.

What are smectic liquid crystals and examples?

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 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 a nematic 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 smectic A?

physics. Liquid crystal arrangements. In nematic arrangements the crystals are randomly positioned with all their long axes pointing in essentially the same direction, given by a vector known as the director.

What is the chiral nematic phase?

The cholesteric (or chiral nematic) liquid crystal phase is typically composed of nematic mesogenic molecules containing a chiral center which produces intermolecular forces that favor alignment between molecules at a slight angle to one another. An important characteristic of the cholesteric mesophase is the pitch.

What is smectic clay?

Smectitic clays, such as bentonites, are the most widely used in peloid therapy, because of their high specific surface area, ion exchange properties, plasticity, expansibility, absorbing capacity and spreadability.

What is the 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.

Which type of liquid crystals are extremely useful for engineers nematic or smectic?

1. Nematic phase. The nematic (N) liquid crystalline phase is technologically the most important of the well-known and widely studied mesophases (nematic, smectic, cholesteric, and columnar). Nematics are also the most used, because they illustrate the best dual nature of liquid crystals.

What is a cholesteric phase?

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 the simplest smectic phase?

The simplest smectic phase is the smectic A (SmA) phase which is represented schematically in Figure 7 (a).

What is the phase transition of a nematic liquid crystal?

The phase transition of a nematic liquid crystal is demonstrated in the following movie provided by Dr. Mary Neubert, LCI−KSU. The nematic phase is seen as the marbled texture. Watch as the temperature of the material is raised, causing a transition to the black, isotropic liquid.

What is a smectic Crystal?

The word “smectic” is derived from the Greek word for soap. This seemingly ambiguous origin is explained by the fact that the thick, slippery substance often found at the bottom of a soap dish is actually a type of smectic liquid crystal. The smectic state is another distinct mesophase of liquid crystal substances.