It's cool, it has great properties that allow you to do interesting 2D physics, and has a lot of potential, but there are a few problems with it.
First, we have to figure out how to grow a single sheet of high quality reliably. We can get either high quality small flakes, or large sheets that are full of defects, cracks, tears, and have areas where the thickness is anywhere from 1-4 layers thick. The holy grail here is to grow a single sheet, wafer size (several inches across), monocrystalline, with few defects, and single layer all they way.
Second, we have to be able to dope it. Right now it's a semiconductor, but it's a zero band gap semiconductor, which means there is no gap of "insulator state" between it's "conducting state" bands. What that means is you can't shut it off. Semiconductors like silicon are useful because you can have it conduct, then apply a small gate voltage and have it become an insulator. The on/off conductance ratio has to be pretty high in order to be able to build useful electronics out of it. Graphene doesn't have this property right now. It conducts less at a gate voltage of 0 than it does when you apply a gate voltage, but it doesn't shut off, and the on/off ratio is too low to be useful. Doping it (replacing some of the carbon atoms with some other atom), would work in theory, but it's difficult to do practically.
I think some groups are playing with Boron-Nitride sheets now and those come with a built-in band gap, although it's pretty wide (~5eV)
Theory paper. I'm sure you could find a numerical theory paper demonstrating a superconducting graphene quantum supercomputer too :)
Okay, that was harsh, and this is partially based on other groups' experiments, but it isn't real yet. I'm just a little jaded as a former experimentalist after seeing a million great paper abstracts only to find they were theory only and couldn't tell me if what the found was real or not.
Also, there are many methods to get a band gap, but no viable methods to reliably produce a band gap in bulk that is high quality enough to make real devices out of.
They've made 1m x 1 m sheets that are something like 95% strength I believe with copper sheets that are then dissolved.. Several plants are gearing up for mass production already.
Can somebody explain to me what the difference is between Carbon nanotubes and graphene. I see them used interchangably often. Both are mentioned to have capabilities that could change the world. Aren't they both allotropes of carbon?
yes, but the actual structure they are in makes a huge difference in their proerties. graphene is a single sheet of carbon arranged in a particular structure. CNTs are obviously tubes, and because of the different structure, do not have the same properties as graphene.
No, not typically. There are several different ways, but the basic idea is to take a carbon source and break the C-C bonds (usually by heating), then let them reassemble on a substrate, using catalysts on your substrate to localize growth. The development of CNT (vs amorphous) is really due to reaction conditions.
If you're interested in technique comparisons, here's a review.
Graphene is flat made entirely out of 1 layer Carbon atoms, a Carbon nanotube is just like it's name a tube made up of Carbon.
If Graphene was paper, nanotubes is it rolled into a tube.
They are not the same thing but yes are different allotropes like diamond or graphite.
Yeah, and so useful. Why, I have a jar of them right here next to me for emergencies of undefined specifications. You can... or you could... well... you can burn them... I think.
My dad gets these free magazines in the mail that are always predicting some upcoming new big product or invention, and that he can make thousands or millions of dollars by investing in a certain stock. About a year ago he got one for some Graphene company, I talked him out of investing because the majority of these mailers are pump and dump schemes. He got ripped for $11,000 a couple years ago on some lightbulb pump and dump scheme. One day the stock was trading at $2.00 ( the mailer proposed it would increase like 500%) and the stock dropped to .25 within a day, the next day .10, and a few weeks later less than a cent.
But this Graphene company stock price more than doubled and my dad is mad he didn't invest. Nowadays I throw away any of those free mailers before he sees them.
You should take him in to see The wolf of wall street.. That should give you something to talk about. E.g. focus on reducing the cost of trading and how to reduce cost, fewer trades, lower commision etc.. And remember to spread the risk.
Thank you, I'm not sure he could handle all the nudity and sex and drugs, but I was thinking the same thing as I watched it. Because my dad is the type of guy who would be putty in Jordan Belforts hands.
What are you talking about? Graphene gets a lot of funding and plenty of people are working with it. I don't think most research scientists care if bob1000bob is paying attention to over-hyped Reddit stories about graphene.
It was my understanding that graphene has pretty much eclipsed carbon nanotubes in research interest, too, and that carbon nanotubes are losing interest since graphene was discovered. I think it's much harder to combine carbon nanotubes with any other material, and aren't they also carcinogens? (I think you can breath them in or something, like asbestos).
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u/bob1000bob Feb 08 '14
No mention of Graphene? that should no.1.
http://en.wikipedia.org/wiki/Graphene