Colloidal crystals


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Colloidal crystals

Periodic arrays of suspended colloidal particles. Common colloidal suspensions (colloids) such as milk, blood, or latex are polydisperse; that is, the suspended particles have a distribution of sizes and shapes. However, suspensions of particles of identical size, shape, and interaction, the so-called monodisperse colloids, do occur. In such suspensions, a new phenomenon that is not found in polydisperse systems, colloidal crystallization, appears: under appropriate conditions, the particles can spontaneously arrange themselves into spatially periodic structures. This ordering is analogous to that of identical atoms or molecules into periodic arrays to form atomic or molecular crystals. However, colloidal crystals are distinguished from molecular crystals, such as those formed by very large protein molecules, in that the individual particles do not have precisely identical internal atomic or molecular arrangements. On the other hand, they are distinguished from periodic stackings of macroscopic objects like cannonballs in that the periodic ordering is spontaneously adopted by the system through the thermal agitation (brownian motion) of the particles. These conditions limit the sizes of particles which can form colloidal crystals to the range from about 0.01 to about 5 micrometers. See Brownian movement, Kinetic theory of matter

The most spectacular evidence for colloidal crystallization is the existence of naturally occurring opals. The ideal opal structure is a periodic close-packed three-dimensional array of silica microspheres with hydrated silica filling the spaces not occupied by particles. Opals are the fossilized remains of an earlier colloidal crystal suspension. Another important class of naturally occurring colloidal crystals are found in concentrated suspensions of nearly spherical virus particles, such as Tipula iridescent virus and tomato bushy stunt virus. Colloidal crystals can also be made from the synthetic monodisperse colloids, suspensions of plastic (organic polymer) microspheres. Such suspensions have become important systems for the study of colloidal crystals, by virtue of the controllability of the particle size and interaction. See Crystal

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In this project, we propose a new process which assembles CNTs and/or graphene into microstructures using microfluidic emulsification followed by large area self-assembly into colloidal crystals.
Six contributed chapters provide an introduction and discuss the Belousov-Zhabotinsky reaction, dynamics of droplets, density oscillators, colloidal crystals, and basic observations and analysis of structural color in nature.
Katsuo Tsukamoto and colleagues say that colloidal crystals such as opals, which form as an orderly array of particles, are of great interest for their potential use in new electronics and optical devices.
Petukhov, AV, Aarits, D, Dolbnaya, IP, de Hoog, EHA, Kassapidou, K, Vroege, GJ, Bras, W, Lekkerkerker, HNW, "High-Resolution Small-Angle X-ray Diffraction Study of Long-Range Order in Hard-Sphere Colloidal Crystals.
Chekesha is doing significant fundamental research in the area of colloidal crystals, which have the potential to revolutionize a number of key technologies including optics and sensing," notes Christopher K.
A research team in the Department of Chemical Engineering at the University of Florida (UF) has developed a spin-coating technique for producing colloidal crystals that mimic the structure of the antireflective coating feature found in the eyes of moths.
Vashishta, "Interfacial Colloidal Crystals and Melting Transition," J.
General topics include supercooled liquids and glasses (including phonons in charged colloidal crystals and elastic models for the non-arrhenius relaxation time of glass-forming liquids), complex fluids (including superionic glass and experimental data), and other related topics such as delayed random walks and control and the effect of Coulomb collisions on low gas pressure plasmas.
Baughman and his colleagues suggest that similar behavior can occur in colloidal crystals, which consist of widely separated, regularly spaced microscopic particles suspended in a liquid; in assemblages of dust particles in electrically charged gases (SN: 8/6/94); and in laser-cooled ion crystals (SN: 1/31/98).
This book also provides an introduction to other areas of crystallisation including self-assembly, classical crystallisation and colloidal crystals.
This idea is based on the concept of field localization by nanoantennas, which will be perfectly applicable to the oriented gold nanorod colloidal crystals.
Colloidal crystals diffract visible light and produce different colors, depending on the spacing of the spheres.