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'Mucking about' with pencil lead and sticky tape wins Nobel Prize for Physics

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Killa-X

Fri Oct 08 2010, 02:53PM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
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Faster speeds because it conducts both electricity and heat...Does this mean possible chance for faster IGBT modules? :) amazing that anyone could have done it. Especially those with microscopes like me...Oh well, just be happy it happend!

IntraWinding

Fri Oct 08 2010, 03:23PM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

As a striking illustration of its extreme properties, the radio programme mentions an experiment where a single graphene layer holds back atmospheric pressure against a vacuum and is impermeable to gasses. No further details are given, but if this works for large areas it certainly sounds impressive to me!

klugesmith

Fri Oct 08 2010, 04:48PM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

IntraWinding wrote ...

As a striking illustration of its extreme properties, the radio programme mentions an experiment where a single graphene layer holds back atmospheric pressure against a vacuum and is impermeable to gasses. No further details are given, but if this works for large areas it certainly sounds impressive to me!

The statement is meaningless without specification of how big an aperture can be spanned without the film bursting.
Whether that's 100 nm or 1000 um, I'm sure the specific sheet strength for graphene is off the charts for conventional materials, but not by an astronomical ratio. Very similar atoms and bonds make high-strength polymer fibers work. If a chain is as strong as its weakest link, it's great when all links are the best kind!

I find it hard to believe that helium would not measurably diffuse through a monolayer of graphene.

Duality

Fri Oct 08 2010, 08:13PM

Registered Member #1951 Joined: Sun Feb 01 2009, 01:59PM
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in the class today someone said that humans could discover more then they already had, and that we already knew every thing.
and then he said: why do we need to know how atoms work?

and we had a good laugh (in physics class).

and this prove's that we haven't learnt all and know all.

and that's hopefully not off topic

just wanted to share it with ya

IntraWinding

Fri Oct 08 2010, 09:24PM

Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581

Klugesmith wrote ...

I was thinking along the same lines so went looking for more specific information.

This paper appears to be the source of the claims:
Impermeable Atomic Membranes from Graphene Sheets

It says Graphene blocks even Helium (and hence, presumably, all other gasses that don't chemically attack it).

The Graphene sealed aperture was a square 4.75 Î¼m on each side which is very large compared to the 0.142nm C-C bond length in Graphene

I make the distance between parallel sides of the carbon hexagons 2(0.142).Cos30Â° = ~0.25nm. Across a 4.75nm span that's about 4.75/0.00025 = ~19,000 hexagons.

If it works over such a large aperture it looks to me as if the ability to hold in excess of atmospheric pressure with no leakage would scale up to any size, which is incredible!

Adam Munich

Fri Oct 08 2010, 10:30PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
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I always wondered if a balloon filled with a vacuum would float. Since balloons rely on positive pressure that was infeasible.

A ball made of gaphine could support a vacuum and weigh nearly nothing at all. Everlasting balloons?

klugesmith

Fri Oct 08 2010, 10:50PM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

IntraWinding wrote ...

The Graphene sealed aperture was a square 4.75 Î¼m on each side which is very large compared to the 0.142nm C-C bond length in Graphene

...
If it works over such a large aperture it looks to me as if the ability to hold in excess of atmospheric pressure with no leakage would scale up to any size, which is incredible!

Thanks for looking up the reference. Wish I had time to read it now. Just seeing the lines you quoted makes me less skeptical about the helium. Certainly scientists with PhD's never misinterpret their experimental results.

The scaling doesn't work the way we'd like.
Burst pressure of a diaphragm of given sheet strength will be proportional to inverse of its diameter.
If you double the diameter and don't change the differential pressure, you have 4x the area, hence 4x the force, but only twice as much material width to bear the load, so the stress will double. At least I bet it will; ain't got time to look up the formula now.

Adam Munich

Sat Oct 09 2010, 03:28AM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

Alright I did the maths and that single layer of carbon is holding back 39.3718965 micrograms (assuming 14psi). That's a mad amount of strength.

dmg

Sat Oct 09 2010, 03:37AM

Registered Member #2628 Joined: Fri Jan 15 2010, 12:23AM
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Killa-X:
"Faster speeds because it conducts both electricity and heat...Does this mean possible chance for faster IGBT modules? :) amazing that anyone could have done it. Especially those with microscopes like me...Oh well, just be happy it happend!"

Well, whatever the future holds for graphene and IGBT modules, it will definatly own any brick ive got!

IGBTs are getting faster and more powerfull with silicon, I think it will only be a matter of time before it is replaced with a newer more powerfull material that will give ratings, and switching speeds that would seem unreal today.

Can you imagine an electric train using SOT-227 (mini-bricklet) sized devices and barely wasting power as heat?

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