Encyclopedia

liquid crystal

Also found in: Dictionary, Wikipedia.
(redirected from smectic)

liquid crystal

[′lik·wəd ′krist·əl]
(physical chemistry)
A liquid which is not isotropic; it is birefringent and exhibits interference patterns in polarized light; this behavior results from the orientation of molecules parallel to each other in large clusters.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

liquid crystal

A liquid crystal is a state of matter between liquid and solid (a "mesophase"). They change shape like a fluid but have the molecular alignment characteristics of a solid crystal. Liquid crystals are composed of organic, rod-shaped molecules that align in parallel, and the common types used in electronic displays are nematic, cholesteric and smectic. See LCD, LCD types and LCD categories.

Nematic LCs
Randomly positioned in parallel, nematic LCs react quickly to electric fields, which is why they are used in the great majority of LCD screens. Meaning "thread" in Greek, nematic LCs are monostable and return to their original alignment when the electric field is removed.

Cholesteric LCs (Chiral Nematic LCs)
Cholesteric LCs are lined up in separate layers that form a spiral (helix). The displays retain their image without power (bistable) but are slower to react to changes than nematic screens. See cholesteric LCD.

Smectic LCs
Positioned side-by-side in layers, smectic LCs are bistable with similar attributes as cholesteric LCs. They retain their image without power and are slower to react than nematics. Smectic means "soapy" in Greek.

Discovered in the 19th Century
In 1888, liquid crystals were identified by Austrian botanist Friedrich Reinitzer and German physicist Otto Lehmann. Studying the cholesterol in carrots using a temperature-controlled polarizing microscope, they noticed that the light passing through the carrot compound (later known as "cholesteryl benzoate") exhibited the refraction effect of a solid crystal when heat was applied. By 1907, Germany-based Merck was selling "liquid and flowing crystal" chemicals.
Copyright © 1981-2025 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.
Mentioned in
References in periodicals archive
Park, "Synthesis and structural studies of smectic C mesogens with terminal perfluoroalkyl chains," Liquid Crystals, vol.
Spatial arrangement of the director axis [??] in three commonly occurring phases of liquid crystals: smectic, nematic and chiral nematic (often termed cholesteric) liquid crystals.
The parent materials are alluvial deposits or alluvial-colluvial pediment deposits or rocks that produce a lot of smectic clay when they weather (limestone and basalts, for example).
He cites more than 20 publications since 1985, many of which he coauthored, that describe similar effects in the types of liquid crystals known as smectic and ferroelectric.
Hervet, "Neutron quasi-elastic scattering study of rotational motions in the smectic C, H and VI phases of terephtal-bis-butyl-aniline (TBBA)," Le Journal de Physique Colloques, vol.
Much has happened in the field since the cloth edition was published in 2003, but rather than trying to stuff all the new developments between paper covers, they focus on nematic photo-elastomers and smectic elastomers.
The ligands are found to exhibit interesting smectic phases (mostly tilted phases) in addition to nematic phases and polymorphism, while the complexes showed orthogonal smectic A, smectic B, and smectic E phases.
They all settle into a liquid-crystal phase known as smectic A, in which the molecules line up to form orderly layers, standing erect in each layer.
Saivada, "Ionic conduction in nematic and smectic a liquid crystals," Molecular Crystals and Liquid Crystals, vol.
Copyright © 2003-2025 Farlex, Inc Disclaimer
All content on this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. This information should not be considered complete, up to date, and is not intended to be used in place of a visit, consultation, or advice of a legal, medical, or any other professional.