Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Columbia engineering team discovers graphene's weakness

01.12.2010
Applied physics professor Chris Marianetti figures out how to shatter the world's strongest material

New York, NY November 29, 2010 In 2008, experiments at The Fu Foundation School of Engineering and Applied Science at Columbia University established pure graphene, a single layer of graphite only one atom thick, as the strongest material known to mankind. This raised a question for Chris Marianetti, Assistant Professor in Columbia Engineering's Department of Applied Physics and Applied Mathematics: how and why does graphene break?

Using quantum theory and supercomputers, Marianetti has revealed the mechanisms of mechanical failure of pure graphene under tensile stress. In a paper recently accepted for publication in the journal Physical Review Letters, he shows that, when graphene is subject to strain equal in all directions, it morphs into a new structure which is mechanically unstable.

Marianetti says this failure mechanism is a novel soft-mode phonon instability. A phonon is a collective vibrational mode of atoms within a crystal, similar to a wave in a liquid. The fact that a phonon becomes "soft" under tensile strain means that the system can lower its energy by distorting the atoms along the vibrational mode and transitioning to a new crystalline arrangement. Under sufficient strain, graphene develops a particular soft-mode that causes the honeycomb arrangement of carbon atoms to be driven towards isolated hexagonal rings. This new crystal is structurally weaker, resulting in the mechanical failure of the graphene sheet.

"This is exciting on many different levels," Marianetti notes. "Soft modes were first recognized in the 1960s in the context of ferroelectric phase transitions, but they have never been directly linked to fracture. Typically, defects in a material will always cause failure to happen prematurely, but the pristine nature of graphene allows one to test our prediction. We have already outlined some interesting new experiments to directly observe our theoretical prediction of the soft mode."

Marianetti added that this is the first time a soft optical phonon has ever been linked to mechanical failure and that therefore it is likely that this novel failure mechanism is not exclusive to graphene but may be prevalent in other very thin materials. "With nanotechnology becoming increasingly ubiquitous, understanding the nature of mechanical behavior in low dimensional systems such as graphene is of great importance. We think strain may be a means to engineer the properties of graphene, and therefore understanding its limits is critical." The research was funded by the National Science Foundation.

Marianetti's research interests lie in the use of classical and quantum mechanics to model the behavior of materials at the atomic scale. In particular, he is focused on applying these techniques to materials with potential for energy storage and conversion. Current applications in his research program range from nuclear materials such as plutonium to rechargeable battery materials such as cobalt oxides.

Marianetti received his BS and MS degrees from Ohio State University and his PhD in materials science and engineering from MIT. Before joining the faculty at Columbia Engineering, he did post-doctoral research in the Department of Physics at Rutgers University and in the Materials Chemistry Division of Lawrence Livermore National Laboratory.

Columbia Engineering

Columbia University's Fu Foundation School of Engineering and Applied Science offers programs to both undergraduate and graduate students who undertake a course of study leading to the bachelor's, master's, or doctoral degree in engineering and applied science. With facilities specifically designed and equipped to meet the laboratory and research needs of faculty and students, Columbia Engineering is home to a broad array of basic and advanced research installations, from the Columbia Center for Electron Transport in Molecular Nanostructures to the Columbia Genome Center. These interdisciplinary centers in science and engineering, materials research, nanoscale research, and genomic research are leading the way in their respective fields while individual groups of engineers and scientists collaborate to solve some of society's more vexing challenges. http://www.engineering.columbia.edu/

Holly Evarts | EurekAlert!
Further information:
http://www.columbia.edu
http://www.engineering.columbia.edu/

More articles from Physics and Astronomy:

nachricht Transportable laser
23.01.2018 | Physikalisch-Technische Bundesanstalt (PTB)

nachricht New for three types of extreme-energy space particles: Theory shows unified origin
23.01.2018 | Penn State

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Optical Nanoscope Allows Imaging of Quantum Dots

Physicists have developed a technique based on optical microscopy that can be used to create images of atoms on the nanoscale. In particular, the new method allows the imaging of quantum dots in a semiconductor chip. Together with colleagues from the University of Bochum, scientists from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute reported the findings in the journal Nature Photonics.

Microscopes allow us to see structures that are otherwise invisible to the human eye. However, conventional optical microscopes cannot be used to image...

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Rutgers scientists discover 'Legos of life'

23.01.2018 | Life Sciences

Seabed mining could destroy ecosystems

23.01.2018 | Earth Sciences

Transportable laser

23.01.2018 | Physics and Astronomy

VideoLinks Science & Research
Overview of more VideoLinks >>>