Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Graphene rips follow rules: Rice University simulations show carbon sheets tear along energetically favorable lines

A series of computer simulations show that under stress, graphene will rip along paths that leave armchair or zigzag edges. Both types of edge favorable for particular electronic applications, said researchers at Rice University, where the simulations were carried out. (Credit: Vasilii Artyukhov/Rice University)
A series of computer simulations show that under stress, graphene will rip along paths that leave armchair or zigzag edges. Both types of edge favorable for particular electronic applications, said researchers at Rice University, where the simulations were carried out. (Credit: Vasilii Artyukhov/Rice University)

Abstract:
Research from Rice University and the University of California at Berkeley may give science and industry a new way to manipulate graphene, the wonder material expected to play a role in advanced electronic, mechanical and thermal applications.

Graphene rips follow rules: Rice University simulations show carbon sheets tear along energetically favorable lines

Houston, TX | Posted on January 5th, 2012

When graphene - a one-atom thick sheet of carbon - rips under stress, it does so in a unique way that puzzled scientists who first observed the phenomenon. Instead of tearing randomly like a piece of paper would, it seeks the path of least resistance and creates new edges that give the material desirable qualities.

Because graphene's edges determine its electrical properties, finding a way to control them will be significant, said Boris Yakobson, Rice's Karl F. Hasselmann Professor of Mechanical Engineering and Materials Science and professor of chemistry.

It's rare that Yakobson's work as a theoretical physicist appears in the same paper with experimental evidence, but the recent submission in Nano Letters titled "Ripping Graphene: Preferred Directions" is a notable exception, he said.

Yakobson and Vasilii Artyukhov, a postdoctoral researcher at Rice, recreated in computer simulations the kind of ripping observed through an electron microscope by researchers at Berkeley.

The California team noticed that cracks in flakes of graphene followed armchair or zigzag configurations, terms that refer to the shape of the edges created. It seemed that molecular forces were dictating how graphene handles stress.

Those forces are robust. Carbon-carbon bonds are the strongest known to man. But the importance of this research, Yakobson said, lies in the nature of the edge that results from the rip. The edge of a sheet of graphene gives it particular qualities, especially in the way it handles electric current. Graphene is so conductive that current flows straight through without impediment - until it reaches the edge. What the current finds there makes a big difference, he said, in whether it stops in its tracks or flows to an electrode or another sheet of graphene.

"Edge energy" in graphene and carbon nanotubes has long been of interest to Yakobson, who issued a paper last year with a formula to define the energy of a piece of graphene cut at any angle. In molecular carbon, armchair and zigzag edges are the most desirable because atoms along the edge are spaced at regular intervals and their electrical properties are well-known: Zigzag graphene is metallic, and armchair graphene is semiconducting. Figuring out how to rip graphene for nanoribbons with edges that are all one type or the other would be a breakthrough for manufacturers.

Yakobson and his team determined that graphene seeks the most energy-efficient path. The Berkeley team noticed that multiple cracks in a flake of graphene flowed strictly along lines that were at (or at multiples of) 30 degrees apart from each other.

"Graphene prefers to tear by expending the least amount of energy," Yakobson said. He noted the 30-degree separation between the angles that differentiate zigzag and armchair in a hexagonal graphene lattice.

To prove it, Artyukhov spent two months building molecular simulations that pulled virtual scraps of graphene apart in various ways. Depending on the force applied, a flake would rip along a straight line or fork in two directions. But the edges produced would always be along 30-degree lines and would be either zigzag or armchair.

"Basically, the direction of the crack in classical fracture theory is determined by the path it could take with the minimal cost in energy," Artyukhov said. "My simulations showed that under some conditions, this could be the case with graphene. It provided a pretty reasonable and clear and solid explanation for this unusual experimental thing."

Artyukhov found that pulling too hard on virtual graphene would shatter it. "Our main effort was to pull on it delicately enough that it has time to pick the direction it would prefer, rather than have a complete failure." He noted the simulations were much faster than rips that would happen in real-world circumstances.

Also surprising was the discovery that rips in graphene across grain boundaries follow the same rules. Tears do not follow the boundary, which would create energetically unfavorable edges, but pass through and switch to the most favorable direction in the new grain.

"The Berkeley folks didn't do controllable tears, but their work opens technological possibilities for the future," Yakobson said. "For electronics, you want ribbons that go in a particular direction, and this research suggests that this is possible. It would be a big deal.

"Think of graphene like a sheet of postage stamps: You apply a load, and you can tear the sheet in a well-defined direction. That's basically what this experiment reveals for graphene," he said. "There are invisible directions prepared for you."

Co-authors are Rice graduate student Yuanyue Liu as well as graduate students Kwanpyo Kim and William Regan and Professors Michael Crommie and Alex Zettl, all of the University of California at Berkeley.

The research was supported by the Department of Energy, the National Science Foundation and the Office of Naval Research (MURI) and by the Lockheed Martin Corp. through LANCER.

####

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:
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

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

Arrowhead Receives Regulatory Clearance to Begin Phase 1/2 Study of ARO-HBV for Treatment of Hepatitis B February 15th, 2018

Arrowhead Pharmaceuticals Receives Orphan Drug Designation for ARO-AAT February 15th, 2018

European & Korean Project To Demo World’s First 5G Platform During Winter Games February 15th, 2018

Graphene/ Graphite

Graphene on toast, anyone? Rice University scientists create patterned graphene onto food, paper, cloth, cardboard February 13th, 2018

A new radiation detector made from graphene: A new bolometer exploits the thermoelectric properties of graphene February 6th, 2018

Engineers develop flexible, water-repellent graphene circuits for washable electronics January 24th, 2018

New catalyst for hydrogen production is a step toward clean fuel: Carbon-based nanocomposite with embedded metal ions yields impressive performance as catalyst for electrolysis of water to generate hydrogen January 16th, 2018

Govt.-Legislation/Regulation/Funding/Policy

Arrowhead Receives Regulatory Clearance to Begin Phase 1/2 Study of ARO-HBV for Treatment of Hepatitis B February 15th, 2018

Arrowhead Pharmaceuticals Receives Orphan Drug Designation for ARO-AAT February 15th, 2018

Rutgers-Led Innovation Could Spur Faster, Cheaper, Nano-Based Manufacturing: Scalable and cost-effective manufacturing of thin film devices February 14th, 2018

Understanding brain functions using upconversion nanoparticles: Researchers can now send light deep into the brain to study neural activities February 14th, 2018

Chip Technology

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

Graphene on toast, anyone? Rice University scientists create patterned graphene onto food, paper, cloth, cardboard February 13th, 2018

Liquid crystal molecules form nano rings: Quantized self-assembly enables design of materials with novel properties February 7th, 2018

Nanometrics Selected for Fab-Wide Process Control Metrology by Domestic China 3D-NAND Manufacturer: Latest Fab Win Includes Comprehensive Suite for Substrate, Thin Film and Critical Dimension Metrology February 7th, 2018

Discoveries

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

'Living bandages': NUST MISIS scientists develop biocompatible anti-burn nanofibers February 15th, 2018

Rutgers-Led Innovation Could Spur Faster, Cheaper, Nano-Based Manufacturing: Scalable and cost-effective manufacturing of thin film devices February 14th, 2018

Understanding brain functions using upconversion nanoparticles: Researchers can now send light deep into the brain to study neural activities February 14th, 2018

Materials/Metamaterials

Rutgers-Led Innovation Could Spur Faster, Cheaper, Nano-Based Manufacturing: Scalable and cost-effective manufacturing of thin film devices February 14th, 2018

Graphene on toast, anyone? Rice University scientists create patterned graphene onto food, paper, cloth, cardboard February 13th, 2018

Atomic Flaws Create Surprising, High-Efficiency UV LED Materials: Subtle surface defects increase UV light emission in greener, more cost-effective LED and catalyst materials February 8th, 2018

A new radiation detector made from graphene: A new bolometer exploits the thermoelectric properties of graphene February 6th, 2018

Announcements

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

Arrowhead Receives Regulatory Clearance to Begin Phase 1/2 Study of ARO-HBV for Treatment of Hepatitis B February 15th, 2018

Arrowhead Pharmaceuticals Receives Orphan Drug Designation for ARO-AAT February 15th, 2018

European & Korean Project To Demo World’s First 5G Platform During Winter Games February 15th, 2018

Military

Graphene on toast, anyone? Rice University scientists create patterned graphene onto food, paper, cloth, cardboard February 13th, 2018

Silk fibers could be high-tech ‘natural metamaterials’ January 31st, 2018

Researchers use sound waves to advance optical communication January 22nd, 2018

New Method Uses DNA, Nanoparticles and Top-Down Lithography to Make Optically Active Structures: Technique could lead to new classes of materials that can bend light, such as for those used in cloaking devices January 18th, 2018

Research partnerships

Rutgers-Led Innovation Could Spur Faster, Cheaper, Nano-Based Manufacturing: Scalable and cost-effective manufacturing of thin film devices February 14th, 2018

Understanding brain functions using upconversion nanoparticles: Researchers can now send light deep into the brain to study neural activities February 14th, 2018

Vanadium dioxyde: A revolutionary material for tomorrow's electronics: Phase-chance switch can now be performed at higher temperatures February 5th, 2018

Nanowire LED Innovator Aledia Announces €30 ($36M) Million Series-C Financing: Intel Capital Joins Existing Investors to Commercialize Certain Nanowire-LED Technologies for Mobile Displays January 29th, 2018

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