Stories tagged graphene
Hey, wait a second...: How could you ever balance one of those on a pencil? Bad science!
Courtesy Matthieu :: giik.net/blogAll y’all up on graphene?
I knew you were. You’re Buzzketeers, the best of the best, the biggest of the brains, the coolest of the cids.
There’s no need to explain graphene to this team (the Lil’ Professors), so it would be totally unnecessary for me to point out that graphene is a fancy material made of a single layer of carbon atoms attached to each other in a honeycomb pattern. It’s about as flat as can be, and when you roll it up you get those little things Science Buzz is so crazy about: carbon nanotubes.
Nanotubes are awesome, and if you click on the link above you can learn about all the awesome things they can do. But graphene…graphene itself may be pretty awesome too. The problem with testing just how awesome graphene is is that it has been exceptionally difficult to a) make a piece of graphene so small that it hasn’t got any of the imperfections that naturally come in large chunks of things, and b) make a device to actually hold the itty bitty graphene well enough to really test the stuff out.
But science has now done those things! Using a tiny sheet of perfect graphene (about 1/100s the width of a human hair) and a really tiny diamond…poker-thing (about 10 billionths of a meter wide), scientists have finally been able to find out exactly how strong graphene is.
So, how strong is it? It’s the strongest! That is to say, the strongest material measured so far. It’s about 200 times the strength of structural steel, or, says Columbia Professor James Hone, “It would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap.”
This statement, of course, wins professor Hone July’s “Awesome explanation, Scientist” award. That’s a good mental image, and it shows a non-scientist like me how strong graphene is.
So…awesome explanation, Scientist! More of that, please!
Tags : Graphene potentially 100x better than silicon
Graphene computer chips: The slightly darker purple area is the graphene, and the lighter purple is the substrate material (SiO2/Si).
Courtesy S. Cho and M. S. Fuhrer, University of Maryland Graphene could replace silicon as the material of choice for many applications like high-speed computer chips and biochemical sensors.
Michael Fuhrer in a paper published online in Nature Nanotechnology explains that in graphene, the intrinsic limit to the mobility, a measure of how well a material conducts electricity, is higher than any other known material at room temperature.
If other extrinsic factors that limit mobility in graphene, such as impurities and lattice vibrations in the substrate on which graphene sits, could be eliminated, the intrinsic mobility in graphene would be more than 100 times higher than silicon.
The low resistivity and extremely thin nature of graphene makes it ideal for applications like touch screens, photovoltaic cells, and chemical and biochemical sensors. The research group was led by principal investigator Michael Fuhrer of the University of Maryland's Center for Nanophysics and Advanced Materials and the Maryland NanoCenter.
Better than silver or gold
Fuhrer said the electrical current in graphene is carried by only a few electrons moving much faster than the electrons in a metal like silver.
"Our current samples of graphene are fairly 'dirty' due to some extraneous sources of resistivity,"
"Once we remove that dirt, graphene, at room temperature, should have about 35 percent less resistivity than silver, the lowest resistivity material known at room temperature."
Roadmap for progress
Because graphene is only one atom thick, current samples must sit on a substrate, in this case silicon dioxide. The electron mobility within the graphene is effected by the substrate. Trapped electrical charges in the silicon dioxide (a sort of atomic-scale dirt) and vibrations of the silicon dioxide atoms can also have an effect on the graphene which are stronger than the effect of graphene's own atomic vibrations.
"We believe that this work points out the importance of these extrinsic effects, and creates a roadmap for finding better substrates for future graphene devices in order to reduce the effects of charged impurity scattering and remote interfacial phonon scattering." Fuhrer said.
Graphene transistor tiniest ever
Graphene from graphite: Graphene is one layer of carbon atoms linked chickenwire-like within graphite. Only one atom thick and less than 50 atoms wide, these "nano" transistors are the smallest in the world. Graphene transistors originally produced at the end of 2004 were very “leaky”. Transistors are like a valves, controlling the flow of an electric current. If they cannot be totally turned off, the leakage results in drained batteries.
Leakage problem solved
Now the Manchester team has found an elegant way around the problem and made graphene-based transistors suitable for use in future computer chips.
Graphene remains highly stable and conductive even when it is cut into strips of only a few nanometres wide.
All other known materials - including silicon - oxidise, decompose and become unstable at sizes tens times larger.
Professor Geim does not expect that graphene-based circuits will come of age before 2025. DailyTech
Professor Andre Geim and Dr Kostya Novoselov from The School of Physics and Astronomy at The University of Manchester reveal details of these transistors, in the March issue of Nature Materials.
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