Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Landscapes give latitude to 2-D material designers

10.08.2017

Rice University, Oak Ridge scientists show growing atom-thin sheets on cones allows control of defects

Rice University researchers have learned to manipulate two-dimensional materials to design in defects that enhance the materials' properties.


Researchers at Rice University and Oak Ridge National Laboratory determined that two-dimensional materials grown onto a cone allow control over where defects called grain boundaries appear. These defects can be used to enhance the materials' electronic, mechanical, catalytic and optical properties.

Credit: Yakobson Research Group/Rice University

The Rice lab of theoretical physicist Boris Yakobson and colleagues at Oak Ridge National Laboratory are combining theory and experimentation to prove it's possible to give 2-D materials specific defects, especially atomic-scale seams called grain boundaries. These boundaries may be used to enhance the materials' electronic, magnetic, mechanical, catalytic and optical properties.

The key is introducing curvature to the landscape that constrains the way defects propagate. The researchers call this "tilt grain boundary topology," and they achieve it by growing their materials onto a topographically curved substrate -- in this case, a cone. The angle of the cone dictates if, what kind and where the boundaries appear.

The research is the subject of a paper in the American Chemical Society journal ACS Nano.

Grain boundaries are the borders that appear in a material where edges meet in a mismatch. These boundaries are a series of defects; for example, when two sheets of hexagonal graphene meet at an angle, the carbon atoms compensate for it by forming nonhexagonal (five- or seven-member) rings.

Yakobson and his team have already demonstrated that these boundaries can be electronically significant. They can, for instance, turn perfectly conducting graphene into a semiconductor. In some cases, the boundary itself may be a conductive subnanoscale wire or take on magnetic properties.

But until now researchers had little control over where those boundaries would appear when growing graphene, molybdenum disulfide or other 2-D materials by chemical vapor deposition.

The theory developed at Rice showed growing 2-D material on a cone would force the boundaries to appear in certain places. The width of the cone controlled the placement and, more importantly, the tilt angle, a crucial parameter in tuning the materials' electronic and magnetic properties, Yakobson said.

Experimental collaborators from Oak Ridge led by co-author David Geohegan provided evidence backing key aspects of the theory. They achieved this by growing tungsten disulfide onto small cones similar to those in Rice's computer models. The boundaries that appeared in the real materials matched those predicted by theory.

"The nonplanar shape of the substrate forces the 2-D crystal to grow in a curved 'non-Euclidian' space," Yakobson said. "This strains the crystal, which occasionally yields by giving a way to the seams, or grain boundaries. It's no different from the way a tailor would add a seam to a suit or a dress to fit a curvy customer."

Modeling cones of different widths also revealed a "magic cone" of 38.9 degrees upon which growing a 2-D material would leave no grain boundary at all.

The Rice team extended its theory to see what would happen if the cones sat on a plane. They predicted how grain boundaries would form over the entire surface, and again, Oak Ridge experiments confirmed their results.

Yakobson said both the Rice and Oak Ridge teams were working on aspects of the research independently. "It was slow going until we met at a conference in Florida a couple of years back and realized that we should continue together," he said. "It was certainly gratifying to see how experiments confirmed the models, while sometimes offering important surprises. Now we need to do the additional work to comprehend them as well."

###

Rice graduate students Henry Yu and Nitant Gupta are co-lead authors of the paper. Co-authors are former Rice postdoctoral researcher Zhili Hu, now at Nanjing University of Aeronautics and Astronautics, and researchers Kai Wang, Bernadeta Srijanto and Kai Xiao of Oak Ridge National Laboratory. Geohegan is the functional hybrid nanomaterials group leader at Oak Ridge's Center for Nanophase Materials Sciences. Yakobson is the Karl F. Hasselmann Professor of Materials Science and NanoEngineering and a professor of chemistry.

The U.S. Department of Energy Basic Energy Sciences and its Center for Nanophase Materials Sciences and the Office of Naval Research supported the research.

Computer resources were provided by the Night Owls Time-Sharing Service and its National Science Foundation-supported DAVinCI supercomputer, both administered by Rice's Center for Research Computing; the resources were procured in partnership with Rice's Ken Kennedy Institute for Information Technology.

Read the abstract at http://pubs.acs.org/doi/abs/10.1021/acsnano.7b03681

This news release can be found online at http://news.rice.edu/2017/08/09/landscapes-give-latitude-to-2-d-material-designers/

Follow Rice News and Media Relations via Twitter @RiceUNews

Related materials:

Yakobson Research Group: http://biygroup.blogs.rice.edu

David Geohegan bio: https://www.ornl.gov/staff-profile/david-b-geohegan

Rice University Materials Science and NanoEngineering: https://msne.rice.edu

Images for download:

http://news.rice.edu/files/2017/08/0814_TILT-1-web-2cn81mr.jpg

Researchers at Rice University and Oak Ridge National Laboratory determined that two-dimensional materials grown onto a cone allow control over where defects called grain boundaries appear. These defects can be used to enhance the materials' electronic, mechanical, catalytic and optical properties. (Credit: Yakobson Research Group/Rice University)

http://news.rice.edu/files/2017/08/0814_TILT-2-web-2iw5qbv.jpg

Two-dimensional materials grown onto a cone allow control over where defects called grain boundaries appear. These defects can be used to enhance the materials' useful properties. (Credit: Yakobson Research Group/Rice University)

http://news.rice.edu/files/2017/08/0814_TILT-3-web-2m20nsf.jpg

A theoretical model at left, created at Rice University, shows a triangular flake of tungsten disulfide grown around a cone that forces the creation of a grain boundary at a specific angle. The Rice researchers showed the width of the cone could be used to determine the placement of the boundary, and scientists at Oak Ridge National Laboratory proved it when they made the matching material seen in the electron microscope image at right. (Credit: Rice University/Oak Ridge National Laboratory)

http://news.rice.edu/files/2017/08/0814_TILT-4-web-1wfcdd7.jpg

Researchers at Rice University and Oak Ridge National Laboratory predict and confirmed that two-dimensional materials grown onto a cone allows control over where defects called grain boundaries appear. At left, a Rice model predicts how a grain boundary would form on a steep cone and extend onto a shallow cone. Scientists at Oak Ridge confirmed the prediction when they created the material seen in an electron microscope image at right. (Credit: Rice University/Oak Ridge National Laboratory)

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 3,879 undergraduates and 2,861 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl.com/RiceUniversityoverview.

Media Contact

Jeff Falk
jfalk@rice.edu
713-348-6775

 @RiceUNews

http://news.rice.edu 

Jeff Falk | EurekAlert!

More articles from Materials Sciences:

nachricht Transporting spin: A graphene and boron nitride heterostructure creates large spin signals
16.08.2017 | Graphene Flagship

nachricht From hot to cold: How to move objects at the nanoscale
10.08.2017 | Scuola Internazionale Superiore di Studi Avanzati

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

Im Focus: Scientists improve forecast of increasing hazard on Ecuadorian volcano

Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).

The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

New thruster design increases efficiency for future spaceflight

16.08.2017 | Physics and Astronomy

Transporting spin: A graphene and boron nitride heterostructure creates large spin signals

16.08.2017 | Materials Sciences

A new method for the 3-D printing of living tissues

16.08.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>