What is smectic A phase?
What is smectic A phase?
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 smectic A liquid crystals?
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 nematic and smectic?
In the nematic phase, only the long axes of the molecules are parallel, and the ends are staggered at random intervals. In the smectic phase, the long axes of the molecules are parallel, and the molecules are also arranged in planes. Liquid crystals tend to form from long, rigid molecules with polar groups.
What does smectic mean?
: 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.
Which type of liquid crystal is colored and changes color with temperature?
Thermochromic Liquid Crystals
Thermochromic Liquid Crystals (LCs) can be highly temperature sensitive, change to many colors, and are more expensive than leuco dyes. LCs start black below their temperature range, go through the colors of a rainbow, and back to black again above the temperature range.
What is Enantiotropic?
: the relation of two different forms of the same substance (such as two allotropic forms of tin) that have a definite transition point and can therefore change reversibly each into the other — compare monotropy.
Which is a feature of the smectic A phase?
For example, the smectic A phase can exhibit the unbroken focal-conic and optically extinct homeotropic textures together, whereas the smectic C phase exhibits broken focal-conic and schlieren textures, and the E phase exhibits banded focal-conic and mosaic textures.
Which is more highly ordered the smectic or nematic phase?
The true smectic phases35 are more highly ordered than the nematic phase and are characterized by partial translational ordering of the molecules into layers, in addition to orientational correlations. The simplest smectic phase is the smectic A (SmA) phase which is represented schematically in Figure 7 (a).
Which is the chiral state of the smectic C phase?
Picture of the smectic C phase Photo of the smectic C phase (using polarizing microscope) As in the nematic, the smectic−C mesophase has a chiral state designated C*. Consistent with the smectic−C, the director makes a tilt angle with respect to the smectic layer. The difference is that this angle rotates from layer to layer forming a helix.
Where does the term smectic liquid crystal come from?
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.