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The author:(作者)qqpublished in(发表于) 2014/6/22 9:38:03 Why Graphene times yet to come？ ，
Why Graphene times yet to come?-Graphene, science and technology, material-IT news Why Graphene times yet to come?
Not long ago, ren zhengfei in an interview claimed that 10-20 years in the future is going to be a revolution, "I think this day and age a great Subversion, Subversion SI era is Graphene times", "chip now limit width, Silicon is between seven nanometers, is approaching the border, graphite is the technology frontier". Graphene is mentioned here, who is it? Did it really brings subversive?
▲ Scanning electron microscopy of Graphene, showing its hexagonal structure composed of carbon atoms. Photo: Lawrence Berkley National Laboratory
Graphene, a two-dimensional carbon only one atom thick film – is kind of amazing material. Although the name of graphite in Word, it does not rely on graphite reserves and is not characteristic of graphite: Graphene bending strength, electrical conductivity, mechanical strength, and look quite magical material of the future style. If the potential use of it again to open a list-protective coatings, transparent bend electronics, Super capacitors and so on--it is the invention that changed the world. Even the 2010 Nobel Prize in physics awarded to it too!
But it has since its inception ten years ago, my transparent phone where is it?
In 2012, because of Graphene, Nobel Prize-winning kangsitanding·nuowoxiaoluofu (Konstantin Novoselov) in nature, and his colleagues have published an article discussing the future of Graphene, basically two years has proven their forecasts. He is considered as a material, Graphene, "prospects are bright, the road has twists and turns", although it could play a significant role in the future, but before overcoming several major difficulties, this scenario will not come. Even more important is that the huge cost of taking into account the industrial upgrade, Graphene benefits may not be enough to allow it to simply replace the existing equipment--it's the real prospects may lie in its unique features tailored to the new applications.
What is Graphene?
Graphene was first discovered by a single layer of atoms of the material. Carbon atoms are connected into a hexagonal grid. Use graphite pencils of countless sheets of Graphene stacked together, carbon nanotubes and Graphene is rolled up into a cylinder-shaped.
▲ Graphite and Graphene, carbon nanotubes and the relationship between ball vinyl. Image source: enago.com
Due to the characteristics of chemical bonds between carbon atoms, Graphene is tough: can be bent to a wide angle without breaking and can resist high pressure. Because only one layer of atoms, electrons confined to a plane of motion, as it brings a whole new electrical properties. Graphene is transparent in visible light, but not breathable. These characteristics make it ideal as a protective layer and transparent materials of electronic products.
But for fit, really do not fast.
One problem: to prepare the way.
Many studies showed it was the striking characteristics of Graphene, but there is a catch. These wonderful properties on the sample quality is very high. To achieve electrical and mechanical properties are the best samples of Graphene, require the most time-consuming and costly means: mechanical exfoliation--gummed on the graphite, hand-stripped of Graphene.
Don't laugh, 2004 novoselov Graphene is how they are prepared.
Novoselov team donated to graphite and Graphene in Stockholm and duct tape. The signature on the tape, "Andre Geim" is a person who together with novoselov won the Nobel Prize. Image credit: Wikipedia
Although the necessary equipment and technical content seems pretty low, but the problem is the success rate is low, research or get some samples, and industrial production? A joke. Discussion on industrialization, it means useless. Even if you get the graphite mine in the world, day by can be stripped off a few ... ...
Of course, now there are a lot of other ways we can increase productivity and reduce costs--the trouble is the quality of these products also fell. We have liquid stripping method: like graphite or carbon-containing materials into the high surface tension of liquids and ultrasonic bomb fried flakes of Graphene. We have a catalytic chemical vapor deposition method: let the carbon-containing gases in the condensation on the surface of copper, forming thin layers of Graphene strip down again. We also have a direct method of growth, two directly managed to grow a Silicon intermediate layer Graphene. Also include chemical oxidation-reduction method, relying on oxygen atom inserted graphite sheet separation, and so on. There are many ways, each with its own scope, but so far there is no really suitable for industrial scale production technology.
Why these approaches can't work out high quality Graphene? For example. Although the central part of a Graphene is perfect six-membered ring, but edge tend to be upset, be five or seven-membered ring. It may seem no big deal, but produced by the catalytic chemical vapor deposition method "a" Graphene is not really complete, from point a growing. It is actually multiple points at the same time the growth of the "poly", and no way can guarantee that multiple small growing points are fully aligned. Thus, these deformed ring not only distributed at the edges, still exists in each "piece" done out of Graphene, structural weaknesses, prone to breakage. Even worse is that Graphene this fracture does not heal like polycrystalline metals, and are likely to be extended indefinitely. Result is that the entire Graphene's strength by half. Material is a problem area, want to have their cake and eat it too is not impossible, but certainly not as fast.
? Microscopic piece of Graphene, false-color tags. Each "color" on behalf of a Graphene "single crystal". Photo: Cornell.edu
Issue II: electrical properties.
Graphene is a promising direction display devices – a touch-screen, electronic paper, and so on. But for now and metallic electrode points of contact resistance of Graphene is hard to deal with. Novoselov is estimated that the problem can be solved in less than a decade.
But why do we not simply discarded metal, all Graphene? This is the most fatal problem in the electronics field. Modern electronics are all building on top of the semiconductor transistor, but it has a key property called "band gap": the electron conduction interval between band and non-conductive. Is precisely because of this interval, the flow of current in order to have asymmetric, circuits in order to have two States: on or off--but the electrical properties of Graphene is too good, it does not have the band gap can only be opened cannot be closed. Only no logic circuits and wires are useless. So will have to create the future of Graphene electronics, replace silicon-based transistors, we must artificially implanted a band gap-but simple implant will lose its unique properties of Graphene. Current research in this area is indeed a lot: laminated, adding other elements, structural change, and so on; but novoselov, who believes the problem to solve, but for at least a decade.
A third question: environmental risk.
Graphene industries also had an unexpected problem: pollution. Graphene industries is currently one of the most sophisticated products may be called "graphene oxide nano-particles", which is very cheap, although not used to make batteries, bend touching screen, such as the high end, as electronic paper and so on are quite nice; but these things are likely to be toxic to the human body. Toxic does not matter, as long as it stay on the electronics, that there would be no problem; but researchers have just found it shortly before in the surface extremely easy to spread. While under the influence of the environment in which it asserts that it is far too early, but it is a potential problem.
So, what is the fate of Graphene? View circles over the past few months and no new breakthroughs, and recently it's this wave of sudden "hot", I am afraid, is primarily a capital of hype running results, should be treated with caution. As industrial technology, Graphene still looks like there are many difficulties could not be overcome. Novoselov pointed out that current applications of Graphene is restricted to material production, so those with the lowest grade, the cheapest Graphene products (such as graphene oxide nano-particles), will be the first one available, might be only a few years, but products that rely on high-purity Graphene may take decades to develop. It will replace the existing product line, novoselov remained skeptical.
The other hand, if businesses exaggerated its magical thing, may result in Graphene into foam; when they burst, then perhaps the technological and industrial development will not save it. Science author feilipu·Baer used in the guardian wrote of the don't expect wonders of Graphene, pointed out that all materials have their scope of application: steel-hard and heavy, wood light but perishable, even seemingly "universal" plastic is also a variety of different polymers have outdone themselves. Graphene will play an important role, but there is no reason to think that it can become the miracle material, changed the world. Alternatively, novoselov's own words: "the true potential of Graphene be fully demonstrated only in completely new areas of application: design considering the material properties of the product, rather than used as a substitute for other materials in existing products. "As for the current product printable, foldable electronic, foldable solar panels, and Super capacitors and so on can fulfil its potential new areas, let us calm down and wait.
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