Definition of a nanotube
The Carbon nanotubes Other elements probably represent the most important product derived from research into fullerenes to date (Hispanic scientists do not agree on the translation of the word fullerene - in different works the original word, or fullerene fullerenes can be found ... We will always use the original used in research circles to avoid confusion) Nanotubes led scientists and Nobel laureates Robert Curl, Harold Kroto, and Richard Smalley to discover the C60 buckyball.
Nanotubes are made up of one or more sheets of graphite or other material wrapped around themselves. Some nanotubes are enclosed by a fullerene half sphere, and others are not enclosed. There are monolayer nanotubes (a single tube) and multilayer (several tubes inserted one inside the other, in the style of the famous Russian dolls). Single-layer nanotubes are called single wall nanotubes (SWNTS) and multi-layered ones, multiplewall nanotubes (MWNT)
Nanotubes have a diameter of a few nanometers and, however, their length can be up to one millimeter, so it has a tremendously high length: width ratio and so far unprecedented.
Research on carbon nanotubes is as exciting (due to its multiple applications and possibilities) and complex (due to the variety of its electronic, thermal and structural properties that change according to diameter, length, way of winding ...).
To better understand nanotubes, you can see this interactive nanotube presentation found in the excellent page on carbon nanostructures published by Professor V.H. Crespo of PennState University.
Carbon nanotubes are the strongest fibers known. A single perfect nanotube is 10 to 100 times stronger than steel per unit weight and has very interesting electrical properties, conducting electrical current hundreds of times more effectively than traditional copper cables.
Graphite (a substance used in pencils) is made up of carbon atoms structured in a panel shape, these panel-like layers are placed one on top of the other. A single layer of graphite is very stable, strong and flexible. Since a layer of graphite is so stable on its own, it adheres weakly to the layers next to it. This is why it is used in pencils - because while writing, small flakes of graphite fall off.
In carbon fibers, the individual layers of graphite are much larger than pencils, and form a long, wavy, and fine, spiral-like structure. These fibers can be glued together and thus form a very strong, light (and expensive) substance used in airplanes, tennis rackets, racing bikes etc.
But there is another way to structure the layers that produces an even stronger material, by winding the panel-like structure to form a graphite tube. This tube is a carbon nanotube.
Carbon nanotubes, in addition to being tremendously resistant, have interesting electrical properties. A graphite layer is a semi-metal. This means that it has intermediate properties between semiconductors (such as silicone in computer microchips, when electrons move with restrictions) and metals (such as copper used in cables when electrons move without restriction) .When a graphite layer is wrapped around In addition to having to align the carbon atoms around the circumference of the tube, a nanotube also has to adjust the quantum mechanical-style wave functions of the electrons. Depending on the exact form in which it is wound, the nanotube can be a semiconductor or a metal.
Definition of a carbon nanotube