sábado, 24 de julio de 2010

Carbon nanobud – revolutionary material discovered in Finland

A new material, the carbon nanobud, has been developed at helsinki University of Technology. It is the only new material discovery of its kind to have been made in Finland.
"As far as I know, discoveries of materials that could really be called 'new materials' have
never been made in Finland before," says Professor Esko I. Kauppinen from Helsinki University of Technology. The carbon nanobud was developed by a research group led by Kauppinen.
They have a patent pending on the carbon nanobud. "Maybe even granted," Kauppinen adds.

Reactive Carbon Nanobud

Let us start with the basics: what on Earth is a carbon nanobud? A carbon nanobud consists of a combination of a carbon nanotube with a spherical carbon molecule called a fullerene.
The various properties of the carbon nanobud are due to the carbon nanotube, which has truly remarkable properties: its graphite bonds are more than a third stronger than the bonds in a diamond. Carbon nanotubes have also excellent electrical conductive properties: they can serve as conductors or semiconductors. Carbon nanotubes can be used to build a sort of a tubing system. Small structures enable the transmission of large amounts of electricity. These tubes are flexible and they have the ability to interweave with each other. Carbon nanotubes are better heat conductors than any other material. The material is also very light.
Kauppinen and his group have succeeded in binding a fullerene to a carbon nanotube with a covalent bond. A carbon nanotube is poorly reactive, but fullerene, due to its chemical properties, enables it to react with other compounds. Carbon nanobuds provide a new dimension by making it possible to associate various properties with carbon nanotubes: electronic and optical applications will be among those impacted by the use of nanobuds.
Having all these properties available in one material, the number of possible applications will be immense.

Transistors and Sound

The Nano building at Helsinki University of Technology embraces research into, for example, carbon nanostructures and production of nanobuds.
"As an example, we are working on electronics and optoelectronics applications: semiconductors and mechanical structures made of carbon nanotubes. The simplest item that carbon nanotubes can be used for is a conductive or semiconductive, transparent, flexible thin film," Kauppinen explains.
Transparent film can be used in, for example, transparent transistors. A semiconductive carbon nanotube works better than silicon as the material for transistors: it endures high currents and is fast and very small in size.
Currently Kauppinen and his group are investigating, among other topics, how carbon nanobuds can be used in loudspeakers. "We have already been able to create sound," says Kauppinen.

Conductive without Iron

Carbon nanotubes and nanobuds can be used in, for example, various new energy storage technologies, such as solar cell electrodes and electron structures of fuel cells, and in various batteries. Using nanotubes has extended the useful age of batteries. Batteries can be loaded several hundreds of times without
the performance being reduced. These types of applications are used in, for instance, mobile phones, cameras, and future electric eco-vehicles.
Kauppinen continues the list of application targets for carbon nanotubes: "We have grown multi-walled nanotubes on cement particles. The concrete we have made is extremely strong and we aim to eliminate iron wiring. Our smallscale testing has already proven that the structure can be made very strong and
electrically conductive. This kind of structure could be used, for example, in floor heating."
"Nanotube film can be made flexible. Concrete applications include, for example, touch screens and e-papers that will be commercially available sooner than we think," Kauppinen continues.

Nanotubes everywhere by 2025

Kauppinen predicts that almost everyone will use products based on nanotubes by the year 2025.
"This is quite possible, if nanotubes are taken into use in computer screens and touch screens. They are already used in the lithium-ion batteries of mobile phones, cameras and portable music players."
Carbon nanotubes are already used in tennis rackets and ice hockey sticks. Nanotubes make these products truly hardwearing. In conductive thin-film materials carbon nanotubes have a major market niche.
"In practice, every screen is covered with a conductive ITO coating prepared from indium and tin oxide spread over glass or a plastic membrane. Over recent years the price of indium has risen by a factor of ten, and it is not possible to make the ITO coating flexible and at the same time sufficiently electrically conductive. Nanotube televisions are also within sight. In these televisions the led-based background lighting in liquid crystal displays will be replaced with carbon nanotube-based field emission light," Kauppinen explains.

Health impacts being studied

Nothing is perfect, and there are always issues to be concerned about. Carbon nanoparticles have been spoken of as the asbestos of the 2000s.
"However, when talking about possible environmental and health impacts, it should be remembered that a large amount of nanoparticles are generated in every burning process, and people have been breathing them throughout history. Nanoparticles are produced in all burning, including combustion in diesel engines and burning of coal, oil, biomass and waste for energy production. Even hydrocarbons generated in natural processes and forest fires produce nanoparticles into the atmosphere. Hence, people have always been exposed to nanoparticles," says Kauppinen.
"Now we are dealing with new nanomaterials, which are not usually airborne but attached to each other and some other macroscopic material, such as plastic in composite applications. Therefore, contact through breathing with the individual nanoparticles in new nanomaterials is very improbable. The most probable exposure phase would be during the nanomaterials production process, should nanoparticles
be released into the air in the production facility as a result of a process malfunction. Hence, the most important thing is to avoid leaks from the reaction chamber and follow meticulously the currently valid guidance on occupational hygiene in production facilities, and to investigate the behavior of different nanomaterials within, for example, cells," Kauppinen continues.
Anni Jakobsson
Mario Pedraza
Electrónica del Estado Sólido
Sección 2

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