Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

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

'Find the Lady' in the quantum world: International team of researchers presents method for quantum-mechanical swapping of positions October 18th, 2017

News and information

'Find the Lady' in the quantum world: International team of researchers presents method for quantum-mechanical swapping of positions October 18th, 2017

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

Spinning strands hint at folding dynamics: Rice University lab uses magnetic beads to model microscopic proteins, polymers October 17th, 2017

Spin current detection in quantum materials unlocks potential for alternative electronics October 15th, 2017

Govt.-Legislation/Regulation/Funding/Policy

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

Spinning strands hint at folding dynamics: Rice University lab uses magnetic beads to model microscopic proteins, polymers October 17th, 2017

Rice U. study: Vibrating nanoparticles interact: Placing nanodisks in groups can change their vibrational frequencies October 16th, 2017

Spin current detection in quantum materials unlocks potential for alternative electronics October 15th, 2017

Nanotubes/Buckyballs/Fullerenes/Nanorods

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

How to draw electricity from the bloodstream: A one-dimensional fluidic nanogenerator with a high power-conversion efficiency September 11th, 2017

Silk could improve sensitivity, flexibility of wearable body sensors August 20th, 2017

Regulation of two-dimensional nanomaterials: New driving force for lithium-ion batteries July 26th, 2017

Discoveries

'Find the Lady' in the quantum world: International team of researchers presents method for quantum-mechanical swapping of positions October 18th, 2017

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

Spinning strands hint at folding dynamics: Rice University lab uses magnetic beads to model microscopic proteins, polymers October 17th, 2017

Rice U. study: Vibrating nanoparticles interact: Placing nanodisks in groups can change their vibrational frequencies October 16th, 2017

Materials/Metamaterials

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

Injecting electrons jolts 2-D structure into new atomic pattern: Berkeley Lab study is first to show potential of energy-efficient next-gen electronic memory October 13th, 2017

The secret to improving liquid crystal's mechanical performance: Better lubricating properties of lamellar liquid crystals could stem from changing the mobility of their structural dislocations by adding nanoparticles October 13th, 2017

Rice U. lab surprised by ultraflat magnets: Researchers create atom-thick alloys with unanticipated magnetic properties October 13th, 2017

Announcements

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

Spinning strands hint at folding dynamics: Rice University lab uses magnetic beads to model microscopic proteins, polymers October 17th, 2017

Rice U. study: Vibrating nanoparticles interact: Placing nanodisks in groups can change their vibrational frequencies October 16th, 2017

Spin current detection in quantum materials unlocks potential for alternative electronics October 15th, 2017

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

'Find the Lady' in the quantum world: International team of researchers presents method for quantum-mechanical swapping of positions October 18th, 2017

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

Spinning strands hint at folding dynamics: Rice University lab uses magnetic beads to model microscopic proteins, polymers October 17th, 2017

Rice U. study: Vibrating nanoparticles interact: Placing nanodisks in groups can change their vibrational frequencies October 16th, 2017

Military

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

Rice U. study: Vibrating nanoparticles interact: Placing nanodisks in groups can change their vibrational frequencies October 16th, 2017

On the road to fire-free, lithium-ion batteries made with asphalt October 12th, 2017

A dash of gold improves microlasers: The precious metal provides a 'nano' solution for improving disease detection, defense and cybersecurity applications October 9th, 2017

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