Nanotechnology Now





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Caps not the culprit in nanotube chirality: Rice University study narrows the possibilities for gaining control of nanotube type

Carbon nanotube caps are forced into shape by six pentagons among the array of hexagons in the single-atom-thick tube. Rice University researchers took a census of thousands of possible caps and found the energies dedicated to their formation have no bearing on the tube's ultimate chirality.Credit: Evgeni Penev/Rice University
Carbon nanotube caps are forced into shape by six pentagons among the array of hexagons in the single-atom-thick tube. Rice University researchers took a census of thousands of possible caps and found the energies dedicated to their formation have no bearing on the tube's ultimate chirality.

Credit: Evgeni Penev/Rice University

Abstract:
A single-walled carbon nanotube grows from the round cap down, so it's logical to think the cap's formation determines what follows. But according to researchers at Rice University, that's not entirely so.

Caps not the culprit in nanotube chirality: Rice University study narrows the possibilities for gaining control of nanotube type

Houston, TX | Posted on February 17th, 2014

Theoretical physicist Boris Yakobson and his Rice colleagues found through exhaustive analysis that those who wish to control the chirality of nanotubes - the characteristic that determines their electrical properties - would be wise to look at other aspects of their growth.



In the study by Yakobson, research scientist Evgeni Penev and postdoctoral researcher Vasilli Artyukhov that was published recently by the American Chemical Society journal ACS Nano, the Rice researchers found that the elastic energy landscapes involved in cap formation are not strong enough to dictate the nanotube's chirality.



To get a clear picture of how caps are related to nanotube chirality, the Rice group embarked upon a detailed, two-year census of the 4,500 possible cap formations for nanotubes of just two diameters, 0.8 and 1 nanometer, across 21 chiralities.



The cap of every nanotube has six pentagons - none of which may touch each other -- among an array of hexagons, Penev said. They pull the cap and force it to curve, but their positions are not always the same from cap to cap.



But because a given chirality can have hundreds of possible caps, the determining factor for chirality must lie elsewhere, the researchers found. "The contribution of the cap is the elastic curvature energy, and then you just forget it," Penev said.



"There are different factors that may be in play," Yakobson said. "One is the energy portion dictated by the catalyst; another one may be the energy of the caps per se. So to get the big picture, we address the energy of the caps and basically rule it out as a factor in determining chirality."



A nanotube is an atom-thick sheet of carbon atoms arranged in hexagons and rolled into a tube. Chirality refers to the hexagons' orientation, and that angle controls how well the nanotube will conduct electricity.



A perfect conducting metallic nanotube would have the atoms arranged in "armchairs," so-called because cutting the nanotube in half would make the top look like a series of wells with atoms for armrests. Turn the hexagons 30 degrees, though, will make a semiconducting "zigzag" nanotube. Nanotubes can be one or the other, or the chiral angle can be anything in between, with a shifting range of electrical properties.



Getting control of these properties has been a struggle. Ideally, scientists could grow the specific kinds of nanotubes they need for an application, but in reality, they grow as a random assortment that must then be separated with a centrifuge or by other means.



Yakobson suspects the answer lies in tuning the interaction between the catalyst and the nanotube edge. "This study showed the energy involved in configuring the cap is reasonably flat," he said. "That's important to know because it allows us to continue to work on other factors."



The work was supported by the Office of Naval Research. The researchers utilized the Data Analysis and Visualization Cyberinfrastructure (DAVinCI) supercomputer supported by the National Science Foundation (NSF) and administered by Rice's Ken Kennedy Institute for Information Technology and the NSF-supported Extreme Science and Engineering Discovery Environment (XSEDE) supercomputer.



Yakobson is Rice's Karl F. Hasselmann Professor of Mechanical Engineering and Materials Science, a professor of chemistry and a member of the Richard E. Smalley Institute for Nanoscale Science and Technology.

####

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 home to the Baker Institute for Public Policy. With 3,920 undergraduates and 2,567 graduate students, Rice's undergraduate student-to-faculty ratio is 6.3-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. 2 for "best value" among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to tinyurl.com/AboutRiceU.

Follow Rice News and Media Relations via Twitter @RiceUNews

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:

Yakobson Group:

Related News Press

Physics

Researchers find the 'key' to quantum network solution May 25th, 2015

News and information

Researchers find the 'key' to quantum network solution May 25th, 2015

One step closer to a single-molecule device: Columbia Engineering researchers first to create a single-molecule diode -- the ultimate in miniaturization for electronic devices -- with potential for real-world applications May 25th, 2015

DNA Double Helix Does Double Duty in Assembling Arrays of Nanoparticles: Synthetic pieces of biological molecule form framework and glue for making nanoparticle clusters and arrays May 25th, 2015

Engineering Phase Changes in Nanoparticle Arrays: Scientists alter attractive and repulsive forces between DNA-linked particles to make dynamic, phase-shifting forms of nanomaterials May 25th, 2015

Govt.-Legislation/Regulation/Funding/Policy

Researchers find the 'key' to quantum network solution May 25th, 2015

One step closer to a single-molecule device: Columbia Engineering researchers first to create a single-molecule diode -- the ultimate in miniaturization for electronic devices -- with potential for real-world applications May 25th, 2015

DNA Double Helix Does Double Duty in Assembling Arrays of Nanoparticles: Synthetic pieces of biological molecule form framework and glue for making nanoparticle clusters and arrays May 25th, 2015

Engineering Phase Changes in Nanoparticle Arrays: Scientists alter attractive and repulsive forces between DNA-linked particles to make dynamic, phase-shifting forms of nanomaterials May 25th, 2015

Nanotubes/Buckyballs/Fullerenes

Basel physicists develop efficient method of signal transmission from nanocomponents May 23rd, 2015

Researchers develop new way to manufacture nanofibers May 21st, 2015

Sandia researchers first to measure thermoelectric behavior by 'Tinkertoy' materials May 20th, 2015

Cotton fibres instead of carbon nanotubes May 9th, 2015

Discoveries

Researchers find the 'key' to quantum network solution May 25th, 2015

One step closer to a single-molecule device: Columbia Engineering researchers first to create a single-molecule diode -- the ultimate in miniaturization for electronic devices -- with potential for real-world applications May 25th, 2015

DNA Double Helix Does Double Duty in Assembling Arrays of Nanoparticles: Synthetic pieces of biological molecule form framework and glue for making nanoparticle clusters and arrays May 25th, 2015

Engineering Phase Changes in Nanoparticle Arrays: Scientists alter attractive and repulsive forces between DNA-linked particles to make dynamic, phase-shifting forms of nanomaterials May 25th, 2015

Materials/Metamaterials

DNA Double Helix Does Double Duty in Assembling Arrays of Nanoparticles: Synthetic pieces of biological molecule form framework and glue for making nanoparticle clusters and arrays May 25th, 2015

Engineering Phase Changes in Nanoparticle Arrays: Scientists alter attractive and repulsive forces between DNA-linked particles to make dynamic, phase-shifting forms of nanomaterials May 25th, 2015

Nanostructures Increase Corrosion Resistance in Metallic Body Implants May 24th, 2015

This Slinky lookalike 'hyperlens' helps us see tiny objects: The photonics advancement could improve early cancer detection, nanoelectronics manufacturing and scientists' ability to observe single molecules May 23rd, 2015

Announcements

Researchers find the 'key' to quantum network solution May 25th, 2015

One step closer to a single-molecule device: Columbia Engineering researchers first to create a single-molecule diode -- the ultimate in miniaturization for electronic devices -- with potential for real-world applications May 25th, 2015

DNA Double Helix Does Double Duty in Assembling Arrays of Nanoparticles: Synthetic pieces of biological molecule form framework and glue for making nanoparticle clusters and arrays May 25th, 2015

Engineering Phase Changes in Nanoparticle Arrays: Scientists alter attractive and repulsive forces between DNA-linked particles to make dynamic, phase-shifting forms of nanomaterials May 25th, 2015

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Researchers find the 'key' to quantum network solution May 25th, 2015

One step closer to a single-molecule device: Columbia Engineering researchers first to create a single-molecule diode -- the ultimate in miniaturization for electronic devices -- with potential for real-world applications May 25th, 2015

DNA Double Helix Does Double Duty in Assembling Arrays of Nanoparticles: Synthetic pieces of biological molecule form framework and glue for making nanoparticle clusters and arrays May 25th, 2015

Engineering Phase Changes in Nanoparticle Arrays: Scientists alter attractive and repulsive forces between DNA-linked particles to make dynamic, phase-shifting forms of nanomaterials May 25th, 2015

Military

This Slinky lookalike 'hyperlens' helps us see tiny objects: The photonics advancement could improve early cancer detection, nanoelectronics manufacturing and scientists' ability to observe single molecules May 23rd, 2015

New Antibacterial Wound Dressing in Iran Can Display Replacement Time May 22nd, 2015

Nanotherapy effective in mice with multiple myeloma May 21st, 2015

Taking control of light emission: Researchers find a way of tuning light waves by pairing 2 exotic 2-D materials May 20th, 2015

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