Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Rice professor's nanotube theory confirmed: Air Force Research Laboratory experiment shows chirality of tube controls speed of growth

A single nanotube stretches out across a microscopic silicon pillar in the Air Force Research Laboratory experiment. (Credit: Rahul Rao/Air Force Research Laboratory)
A single nanotube stretches out across a microscopic silicon pillar in the Air Force Research Laboratory experiment.

(Credit: Rahul Rao/Air Force Research Laboratory)

Abstract:
The Air Force Research Laboratory in Dayton, Ohio, has experimentally confirmed a theory by Rice University Professor Boris Yakobson that foretold a pair of interesting properties about nanotube growth: That the chirality of a nanotube controls the speed of its growth, and that armchair nanotubes should grow the fastest.

Rice professor's nanotube theory confirmed: Air Force Research Laboratory experiment shows chirality of tube controls speed of growth

Houston, TX | Posted on January 30th, 2012

The work is a sure step toward defining all the mysteries inherent in what Yakobson calls the "DNA code of nanotubes," the parameters that determine their chirality -- or angle of growth -- and thus their electrical, optical and mechanical properties. Developing the ability to grow batches of nanotubes with specific characteristics is a critical goal of nanoscale research.

The new paper by Air Force senior researcher Benji Maruyama; former Air Force colleague Rahul Rao, now at the Honda Research Institute in Ohio; Yakobson and their co-authors appeared this week in the online version of the journal Nature Materials.

It's an interesting denouement in a saga that began with a 2009 paper by Yakobson and his collaborators. That paper, which presented the theoretical physicist's dislocation theory of chirality-controlled growth, described how nanotubes emerge as if single threads of atoms weave themselves into the now-familiar chicken-wire-like tubes. It also garnered a bit of controversy over what precisely the results meant.

"Boris caught some heat over it," Maruyama said. "The experimental work out there indicated his theory might be true, but they couldn't confirm it. The good part about our work is that it's fairly unambiguous."

Yakobson, Rice's Karl F. Hasselmann Professor of Mechanical Engineering and Materials Science and professor of chemistry, took it all in stride. "The criticism didn't affect anything; it was actually the best advertisement and motivation for further work," he said. "In fact, (nanotube pioneer Sumio) Iijima noted early that 'helicity may aid the growth.' We have transformed it into a verifiable equation."

Experimental confirmation of a theory is never final but always satisfying, he admitted, and the Air Force lab was uniquely equipped to prove the linkage between the speed of a nanotube's growth and its chiral angle.

The chirality of a single-walled nanotube is determined by the way its carbon atoms are "rolled." Yakobson has described it as similar to rolling up a newspaper; sometimes the type lines up, and sometimes it doesn't. That alignment determines the nanotubes' electrical properties. Metallic armchair nanotubes, so named for the shape of their uncapped edges, are particularly desirable because electrons pass through from tip to tip with no resistance, while semiconducting nanotubes are useful for electronics, among other applications.

Rao developed a technique in Maruyama's lab to measure the growth rates of individual nanotubes. "It's an impressive setup," Yakobson said. "They can grow individual tubes in very low density and identify their signatures - their chirality - and at the same time measure how rapidly they grow."

The technique involved mounting catalyst nanoparticles on microscopic silicon pillars and firing tightly controlled lasers at them. Heat from the laser triggered the nanotubes to grow through a standard technique called chemical vapor deposition, and at the same time, the researchers analyzed nanotube growths via Raman spectroscopy.

From the spectra, they could tell how fast a nanotube grew and at what point growth terminated. Subsequent electron microscope images confirmed the spectra were from individual single-walled nanotubes, while chiral angles were determined by comparing post-growth Raman spectra and nanotube diameters to the Kataura plot, which maps chirality based on band gap and diameter.

They noted in the paper that the results provide a basis for further research into growing specific types of nanotubes. "Now that we know what the growth rate is for a particular chirality nanotube, one could think about trying to achieve growth of that specific chirality by influencing growth conditions accordingly," Rao said. "So, basically, we now have another 'knob' to turn."



"This work is at a very early development stage, and it's all about post-nucleation," Yakobson said. "Nucleation sets what I think of as the genetic code - very primitive compared to biology - that determines the chirality and the speed of growth of a nanotube." He said it may be possible someday to dictate the form of a nanotube as it begins to bubble up from a catalyst, "but it will take a lot of ingenuity."



Yakobson revealed a formula last year that defined the nucleation probability through the edge energies for graphene, which is basically a cut-and-flattened nanotube. But the earlier and related dislocation theory applies to the following growth, and if confirmed further may turn out to be his masterwork.

"The dislocation theory of growth is elegant and simple," Rao said. "It's still too early to say that it is the only growth mechanism, but Boris should be given plenty of credit for proposing this bold idea in the first place."

Co-authors are former Rice graduate student Tonya Leeuw Cherukuri and David Liptak, both researchers at the Air Force lab.

The Air Force Office of Scientific Research and the National Research Council funded the work.

####

About Rice University
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is known for its "unconventional wisdom." With 3,708 undergraduates and 2,374 graduate students, Rice's undergraduate student-to-faculty ratio is less than 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice has been ranked No. 1 for best quality of life multiple times by the Princeton Review and No. 4 for "best value" among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to www.rice.edu/nationalmedia/Rice.pdf.

For more information, please click here

Contacts:
David Ruth
713-348-6327


Mike Williams
713-348-6728

Copyright © Rice University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Read the abstract at:

Related News Press

News and information

Scientists refine formula for nanotube types: Rice University theorists determine factors that give tubes their chiral angles September 17th, 2014

New non-invasive technique could revolutionize the imaging of metastatic cancer September 17th, 2014

Toward making lithium-sulfur batteries a commercial reality for a bigger energy punch September 17th, 2014

Recruiting bacteria to be technology innovation partners: September 17th, 2014

Laboratories

Elusive Quantum Transformations Found Near Absolute Zero: Brookhaven Lab and Stony Brook University researchers measured the quantum fluctuations behind a novel magnetic material's ultra-cold ferromagnetic phase transition September 15th, 2014

'Squid skin' metamaterials project yields vivid color display: Rice lab creates RGB color display technology with aluminum nanorods September 15th, 2014

Berkeley Lab Licenses Boron Nitride Nanotube Technology: New material has unique mechanical and electronic properties September 13th, 2014

Advanced Light Source Sets Microscopy Record| Berkeley Lab Researchers Achieve Highest Resolution Ever with X-ray Microscopy September 11th, 2014

Govt.-Legislation/Regulation/Funding/Policy

Scientists refine formula for nanotube types: Rice University theorists determine factors that give tubes their chiral angles September 17th, 2014

New non-invasive technique could revolutionize the imaging of metastatic cancer September 17th, 2014

Recruiting bacteria to be technology innovation partners: September 17th, 2014

Nanoribbon film keeps glass ice-free: Rice University lab refines deicing film that allows radio frequencies to pass September 16th, 2014

Nanotubes/Buckyballs

Scientists refine formula for nanotube types: Rice University theorists determine factors that give tubes their chiral angles September 17th, 2014

‘Small’ transformation yields big changes September 16th, 2014

Rice rolls 'neat' nanotube fibers: Rice University researchers' acid-free approach leads to strong conductive carbon threads September 15th, 2014

Berkeley Lab Licenses Boron Nitride Nanotube Technology: New material has unique mechanical and electronic properties September 13th, 2014

Discoveries

Scientists refine formula for nanotube types: Rice University theorists determine factors that give tubes their chiral angles September 17th, 2014

New non-invasive technique could revolutionize the imaging of metastatic cancer September 17th, 2014

Toward making lithium-sulfur batteries a commercial reality for a bigger energy punch September 17th, 2014

Recruiting bacteria to be technology innovation partners: September 17th, 2014

Announcements

New NPZ100-403 Piezo Stage from nPoint Inc. September 17th, 2014

Scientists refine formula for nanotube types: Rice University theorists determine factors that give tubes their chiral angles September 17th, 2014

New non-invasive technique could revolutionize the imaging of metastatic cancer September 17th, 2014

Toward making lithium-sulfur batteries a commercial reality for a bigger energy punch September 17th, 2014

Military

Scientists refine formula for nanotube types: Rice University theorists determine factors that give tubes their chiral angles September 17th, 2014

Nanoribbon film keeps glass ice-free: Rice University lab refines deicing film that allows radio frequencies to pass September 16th, 2014

'Squid skin' metamaterials project yields vivid color display: Rice lab creates RGB color display technology with aluminum nanorods September 15th, 2014

Fonon at Cutting-Edge of 3D Military Printing: Live-Combat Scenarios Could See a Decisive Advantage with 3D Printing September 15th, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE