What is a smectic phase?
physics. Share. 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 nematic phase transition?
One of the most common phases is the nematic phase, in which the molecules tend to have the same alignment, but their positions are not correlated. Phase transitions between different phases give rise to a variety of mathematical questions of great interest.
What is smectic A?
: of, relating to, or being the phase of a liquid crystal characterized by arrangement of molecules in layers with the long molecular axes in a given layer being parallel to one another and those of other layers and perpendicular or slightly inclined to the plane of the layer — compare cholesteric, nematic.
What are smectic liquid crystals and examples?
Smectic C is a smectic A like structure in which the long axes of the molecules of a tilted average angle differing from 90° with respect to the plane of the layer in a “bookshelf” arrangement. Light can be diffracted off the periodic spaces give a variety of patterns.
What are smectic liquid crystals with examples?
Summary of Phases and Order
| untilted | tilted |
|---|---|
| Smectic-A | Smectic-C layering breaks translational symmetry; in smectic-C molecules are tilted |
| Hexatic SBSI SK | Like the smectic A they are stacks of liquid layers but the molecules tend to be positioned along a hexagonal lattice within each plane |
What is nematic structure?
The nematic phase, abbreviated as N, has the simplest structure of all of the mesophases, is very fluid, and is also the least ordered mesophase. The word nematic comes from the Greek nematos meaning thread-like—this arises from the observed optical texture of the phase between crossed polarizers (vide infra).
What is the structure of nematic liquid crystal?
The general structure of nematic liquid crystal compounds is composed of aromatic cycles which are planar, rigid, and polarizable, connected by conjugated double bonds along the long axis of the molecule.
What are lyotropic liquid crystals and their applications?
Thermotropic liquid crystals (TLCs) are temperature dependent and formed by pure amphiphilic molecules or mixtures. The TLC has molecular geometry in the formats of rods, disks, and banana-shaped and are mostly used in technological applications as displays and sensor devices [106,111,112].
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 the difference between smectic I and SMF?
Thus, the smectic I (SmI) phase may be regarded as an SmB phase which is tilted toward a ‘vertex’ of the hexagonal net, while the smectic F (SmF) phase may be regarded as an SmB phase which is tilted toward the ‘edge’ of the hexagonal net ( Figure 8 ). Figure 8.
What is the smectic state?
The smectic state is another distinct mesophase of liquid crystal substances. Molecules in this phase show a degree of translational order not present in the nematic. In the smectic state, the molecules. Phases of Liquid Crystals http://plc.cwru.edu/tutorial/enhanced/files/lc/phase…