_Fundamental Concept_
_Size Concerns_
_Materials Used_
_Chemical Processing of Ceramics_
Materials referred to as "nanomaterials" generally fall into two categories: fullerenes, and inorganic nanoparticles.
Fullerenes
The fullerenes are a class of allotropes of carbon, which is conceptually graphs sheets rolled into tubes or balls. These include carbon nanotubes, which are of interest both because of their mechanical strength and also because of their electrical properties.For the last decade, chemical and physical properties of fuller's been a hot topic in research and development, and will likely continue to be too long. In April 2003 the fuller was under study for potential medicinal use: binding specific antibiotics to the structure of resistant bacteria and even target certain cancer cells such as melanoma. From the October 2005 issue of chemistry and biology, contains an article describing the use of fuller's as light-activated antimicrobial agents. In nanotechnology, heat resistance and superconductivity are among the properties attract intense research.
A common method used to produce fuller agree to send a large current between two nearby graphite electrodes in an inert atmosphere. The resulting carbon plasma arc between the electrodes cools into sooty residue from which many fuller stocks can be isolated.
There are many calculations that have been performed using ab-initio quantum methods used for the fullernes. By DFT and TDDFT methods can achieve IR, raman and UV spectra. The results of these calculations can be compared with experimental results.
Nanoparticles
Nanoparticles or nanocrystals made of metals, semiconductors or oxides are of particular interest for their mechanical, electrical, magnetic, optical, chemical and other properties. Nanoparticles have been used as quantum dots and as chemical catalysts.Nanoparticles are of great scientific interest because they are actually a bridge between bulk materials and atomic or molecular structures. A bulk material should have constant physical properties regardless of its size, but at the nano-scale this is often not the case. Size-dependent properties are observed such as quantum confinement in semiconductor particles, surface plasmon resonance in some metal particles and superparamagnetism in magnetic materials.
Nanoparticles exhibit a number of special properties compared to bulk material. For example, the bending of bulk copper (wire, tape, etc.) arising from the movement of copper atoms / clusters at about 50 nm scale. Copper nanoparticles smaller than 50 nm are considered super hard materials that do not exhibit the same malleability and ductility as bulk copper. The change in properties is not always desirable. Ferroelectric materials smaller than 10 nm can switch their magnetisation direction using room temperature thermal energy, thus making them useless for memory storage. Suspensions of nanoparticles are possible because of the interaction of the particle size surface with the solvent is strong enough to overcome differences in density, usually resulting in a material either sinking or floating in a liquid. Nanoparticles often have unexpected visual properties, because they are small enough to limit their electrons and produce quantum effects. For example gold nanoparticles appear deep red to black in solution.
They are often very high surface area to volume ratio of nanoparticles provides a tremendous driving force for diffusion, especially at high temperatures. Sintering is possible at lower temperatures and over shorter periods than for larger particles. This theory does not affect the density of the final product, though flow difficulties and the tendency of nanoparticles to make the cake complicated. The surface effects of nanoparticles also reduces the incipient melting temperature.
