Nanostructure

(solid-state physics) Something that has a physical dimension smaller than 100 nanometers, ranging from clusters of atoms to dimensional layers.

A material structure assembled from a layer or cluster of atoms with size of the order of nanometers. Interest in the physics of condensed matter at size scales larger than that of atoms and smaller than that of bulk solids (mesoscopic physics) has grown rapidly since the 1970s, owing to the increasing realization that the properties of these mesoscopic atomic ensembles are different from those of conventional solids. As a consequence, interest in artificially assembling materials from nanometer-sized building blocks arose from discoveries that by controlling the sizes in the range of 1–100 nm and the assembly of such constituents it was possible to begin to alter and prescribe the properties of the assembled nanostructures.

Nanostructured materials are modulated over nanometer length scales in zero to three dimensions. They can be assembled with modulation dimensionalities of zero (atom clusters or filaments), one (multilayers), two (ultrafine-grained overlayers or coatings or buried layers), and three (nanophase materials), or with intermediate dimensionalities.

Multilayers and clusters

Multilayered materials have had the longest history among the various artificially synthesized nanostructures, with applications to semiconductor devices, strained-layer superlattices, and magnetic multilayers. Recognizing the technological potential of multilayered quantum heterostructure semiconductor devices helped to drive the rapid advances in the electronics and computer industries. A variety of electronic and photonic devices could be engineered by utilizing the low-dimensional quantum states in these multilayers for applications in high-speed field-effect transistors and high-efficiency lasers, for example. Subsequently, a variety of nonlinear optoelectronic devices, such as lasers and light-emitting diodes, have been created by nanostructuring multilayers.

The advent of beams of atom clusters with selected sizes allowed the physics and chemistry of these confined ensembles to be critically explored, leading to increased understanding of their potential, particularly as the constituents of new materials, including metals, ceramics, and composites of these materials. A variety of carbon-based clusters (fullerenes) have also been assembled into materials of much interest. In addition to effects of confinement, interfaces play an important and sometimes dominant role in cluster-assembled nanophase materials, as well as in nanostructured multilayers. See also Atom cluster; Fullerene.

Synthesis and properties

A number of methods exist for the synthesis of nanostructured materials. They include synthesis from atomic or molecular precursors (chemical or physical vapor deposition, gas condensation, chemical precipitation, aerosol reactions, biological templating), from processing of bulk precursors (mechanical attrition, crystallization from the amorphous state, phase separation), and from nature (biological systems). Generally, it is preferable to synthesize nanostructured materials from atomic or molecular precursors, in order to gain the most control over a variety of microscopic aspects of the condensed ensemble; however, other methodologies can often yield very useful results.

Part of a series of articles on Nanomaterials Fullerenes Carbon nanotubes Fullerene chemistry Applications In popular culture Timeline Carbon allotropes Nanoparticles Quantum dots Nanostructures Colloidal gold Silver nanoparticles Iron nanoparticles Platinum nanoparticles See also Nanotechnology  v • d • e

A nanostructure is an object of intermediate size between molecular and microscopic (micrometer-sized) structures.

In describing nanostructures it is necessary to differentiate between the number of dimensions on the nanoscale. Nanotextured surfaces have one dimension on the nanoscale, i.e., only the thickness of the surface of an object is between 0.1 and 100 nm. Nanotubes have two dimensions on the nanoscale, i.e., the diameter of the tube is between 0.1 and 100 nm; its length could be much greater. Finally, spherical nanoparticles have three dimensions on the nanoscale, i.e., the particle is between 0.1 and 100 nm in each spatial dimension. The terms nanoparticles and ultrafine particles (UFP) often are used synonymously although UFP can reach into the micrometre range. The term 'nanostructure' is often used when referring to magnetic technology.

List of nanostructures

• Nanocages
• Nanocomposite
• Nanofabrics
• Nanofiber
• Nanoflake
• Nanoflower
• Nanofoam
• Nanomesh
• Nanoparticle
• Nanopillar
• Nanopin film
• Nanoring
• Nanorod
• Nanoshell
• Quantum dot
• Quantum heterostructure
• Sculptured thin film

See also

• Nanomaterials
• Nanotechnology

External links

• Nano Flakes May Revolutionize Solar Cells.
• Applications of Nanoparticles

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