Photonic Colloidal Crystals

A colloid is a suspension or dispersion of one substance inside another, typically held in place by electromagnetic fields. Examples of common colloids include, blood, milk, ink, gelatin, smoke and fog particles. Destabilizing the electromagnetic field often causes the particles to precipitate out of their suspended state. Colloidal particles can also self-assemble or crystallize into lattice array structures known as colloidal crystals or colloidal nano-crystals. Opals are an example of fossilized colloidal crystals made up of silica spheres. Colloidal crystals can also be created synthetically and often exhibit interesting photonic properties allowing them to be used to control the flow of light.

Water and Colloid Crystals – [i-sis.org.uk]

Colloids are particles of nanometres (10 -9 m) up to several micrometer dimensions (also commonly referred to as nanoparticles) that exist as suspensions in water or other solvents; and colloid crystals are literally crystals made of colloid particles arranged in an orderly way, like atoms in ordinary crystals. Also like ordinary crystals, and macromolecules in living organisms, colloid crystals self-assemble, that is, they form spontaneously when precipitated or evaporated from suspension onto a substrate such as a carbon or silicon-oxide film. The same colloids can self-assemble into a variety of crystals according to the conditions of crystallisation, for example, temperature, pH, ionic and other additives. These three-dimensional colloid crystals are finding applications as electronic and photonic devices [1].

Colloidal crystals of ordered microspheres – a new class of advanced materials – [nanowerk.com]

Colloidal crystals constructed by monodispersed microspheres packed in ordered arrays represent a new class of advanced materials that are useful in many areas. For example, due to their novel light diffraction and photonic bandgap properties, colloidal crystals are promising elements in the fabrication of devices such as optical filters and switches, chemical and biochemical sensors, and photonic chips. Various self-assembly techniques have been developed to form colloidal crystals on different substrates, including the flow-cell methods, vertical deposition, micromolding in capillaries and so on. Although existing methods can provide colloidal crystals of different structures and quality, efficient approaches to high stability and large scale colloidal crystals are increasingly attracting attention. Generating ordered microstructures in the colloidal crystal films and colloidal crystals with different structures and configurations are particularly important in the fabrication of optical devices.

COLLOIDAL CRYSTALS – [buffalo.edu]

Contents

  • Introduction
  • Formation of the Super-lattice
  • Types of colloidal crystals
  • Methods of Synthesis
  • Applications

SEE ALSO:
Metamaterials
Quasicrystals
Raman Optical Amplifiers

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