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Carbon nanotubes: The weird world of 'remote Joule heating'



April 10, 2012 – Comments (3)

More carbonaceous awesomeness. I like the potential CPU applications a lot.


Carbon nanotubes: The weird world of 'remote Joule heating'
April 10, 2012

( -- A team of University of Maryland scientists have discovered that when electric current is run through carbon nanotubes, objects nearby heat up while the nanotubes themselves stay cool, like a toaster that burns bread without getting hot. Understanding this completely unexpected new phenomenon could lead to new ways of building computer processors that can run at higher speeds without overheating.

"This is a new phenomenon we're observing, exclusively at the nanoscale, and it is completely contrary to our intuition and knowledge of Joule heating at larger scales-for example, in things like your toaster," says first author Kamal Baloch, who conducted the research while a graduate student at the University of Maryland. "The nanotube's electrons are bouncing off of something, but not its atoms. Somehow, the atoms of the neighboring materials-the silicon nitride substrate-are vibrating and getting hot instead."

"The effect is a little bit weird," admits John Cumings, an assistant professor in the Department of Materials Science and Engineering who oversaw the research project. He and Baloch have dubbed the phenomenon "remote Joule heating."

An Unreal Discovery

For the UMD researchers, the experience of the discovery was like what you or I might have felt, if, on a seemingly ordinary morning, we began to make breakfast, only to find certain things happening that seem to violate normal reality. The toast is burned, but the toaster is cold. The switch on the stove is set to "HI" and the teapot is whistling, but the burner isn't hot.

Of course, Baloch, Cumings and their colleagus weren't making breakfast in a kitchen, but running experiments in an electron microscopy facility at the A. James Clark School of Engineering at the University of Maryland.  They ran their experiments over and over, and the result was always the same: when they passed an electrical current through a carbon nanotube, the substrate below it grew hot enough to melt metal nanoparticles on its surface, but the nanotube itself seemed to stay cool, and so did the metal contacts attached to it.

For us non-scientists, their experience might not seem so strange at first glance-after all, food cooked in a microwave oven gets hot while the oven itself stays close to room temperature. The problem is that Baloch and Cumings weren't intentionally generating a microwave field. They were only passing a direct electrical current through the nanotube, which should have caused it to heat up. The data were telling them a story that didn't seem to make any sense-one about a plugged-in toaster that could burn bread without getting hot.

3 Comments – Post Your Own

#1) On April 11, 2012 at 8:04 AM, lemoneater (57.06) wrote:

As a carbon based life form, I found this article cool on several counts.

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#2) On April 11, 2012 at 8:41 AM, binve (< 20) wrote:


>> As a carbon based life form, I found this article cool on several counts.

lol ! Nice turn of phrase on the remote heating concept :) Thanks!

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#3) On April 11, 2012 at 4:52 PM, lemoneater (57.06) wrote:

I sent the link to my husband who also enjoyed it. The potential of carbon material is amazing. Glad you enjoyed the pun. :)

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