Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



TECH SPACE
Controlling the properties of matter in two-dimensional crystals
by Staff Writers
University Park PA (SPX) Nov 08, 2016


This is an electron microscopy image of ordered atoms of tungsten (W) and molybdenum (Mo) against artistic representations of triangular single layer flakes of WxMo1-xS2 on a substrate. Image courtesy Amin Azizi and Andrea Kohler and Penn State. For a larger version of this image please go here.

By creating atomic chains in a two-dimensional crystal, researchers at Penn State believe they have found a way to control the direction of materials properties in two and three dimensional crystals with implications in sensing, optoelectronics and next-generation electronics applications. Whether an alloy has a random arrangement of atoms or an arrangement that is ordered can have large effects on a material's properties.

In a paper published online in Nano Letters, Nasim Alem, assistant professor of materials science and engineering, and colleagues at Penn State used a combination of simulations and scanning transmission electron microscopy (STEM) imaging to determine the atomic structure of an ordered alloy of molybdenum, tungsten and sulfur. They determined that fluctuations in the amount of available sulfur were responsible for the creation of atomic chains of either molybdenum or tungsten.

"We discovered how chains form in a two-dimensional alloy as a result of fluctuations in the amount of a particular precursor, in this case sulfur," said Alem.

"Normally, when we combine atoms of different elements, we don't know how to control where the atoms will go. But we have found a mechanism to give order to the atoms, which in turn introduces control of the properties, not only heat transport, as is the case in this work, but also electronic, chemical or magnetic properties in other alloy cases. If you know the mechanism, you can apply it to arrange the atoms in a wide range of alloys in 2D crystals across the Periodic Table."

In the case of the molybdenum, tungsten and sulfur alloy, they showed that the electronic properties were the same in every direction, but using simulations they predict that the thermal transport properties are smaller perpendicular to the chains or stripes.

"We didn't know why this crystal forms an ordered structure, so we worked with my colleague Dr. Vin Crespi to understand the underlying physics that causes order in this crystal," said Alem. "Our calculations show it was the fluctuations in the third element, sulfur, that was determining how the chains formed."

Vincent H. Crespi, Distinguished Professor of Physics, and professor of chemistry and materials science and engineering who developed the theoretical understanding of the phenomenon, said, "Although the interior of the flake is indifferent to whether molybdenum or tungsten occupies any site in the crystal lattice, the edge of the growing crystal does care.

Depending on how much sulfur is available at a given location, the edge will prefer to be either 100 percent molybdenum or 100 percent tungsten. So as the availability of sulfur randomly varies during growth, the system alternately lays down rows of molybdenum or tungsten. We think this may be a general mechanism to create stripe-like structures in 2D materials."

Amin Aziz, a Ph.D. candidate in Alem's group and lead author, produced the STEM imaging and spectroscopy that showed the fine atomic structure of the alloy samples and their electronic properties.

"When we are able to directly image constitutive atoms of a substance, see how they interact with each other at the atomic level and try to understand the origins of such behaviors, we could potentially create new materials with unusual properties that have never existed," said Azizi,

A team led by Mauricio Terrones, professor of physics, produced samples of this ordered alloy by vaporizing powders of all three elements, called precursors, under high heat.

Along with Azizi, Terrones, Alem and Crespi, other coauthors on the paper titled "Spontaneous formation of atomically thin stripes in transition metal dichalcogenide monolayers," include Yuanxi Wang, a Ph.D. candidate in Crespi's group, Ke Wang, a staff scientist in the Materials Research Institute who helped with the electron microscopy, Ph.D. candidate Zhong Lin in materials science and Ana Laura Elias, research associate in the Terrones group.


Comment on this article using your Disqus, Facebook, Google or Twitter login.


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only

.


Related Links
Penn State
Space Technology News - Applications and Research






Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
TECH SPACE
Lehigh scientists fabricate a new class of crystalline solid
Bethlehem PA (SPX) Nov 08, 2016
Scientists at Lehigh University, in collaboration with Lawrence Berkeley National Laboratory, have demonstrated the fabrication of what they call a new class of crystalline solid by using a laser heating technique that induces atoms to organize into a rotating lattice without affecting the macroscopic shape of the solid. By controlling the rotation of the crystalline lattice, the researche ... read more


TECH SPACE
Progress, but uphill slog for women in tech

NavCube could support an X-ray communication test in space

NASA, Navy practice Orion module recovery

Weightless tourism just 4 years away

TECH SPACE
JCSAT-15 arrives in Kourou for Dec Ariane 5 launch

Aerojet Rocketdyne completes CST launch abort engine hot fire tests

China launches first heavy-lift rocket

NASA Uses Tunnel Approach to Study How Heat Affects SLS Rocket

TECH SPACE
Mars' ionosphere shaped by crustal magnetic fields

Iron-Loving Bacteria A Model For Mars Life

Opportunity makes small U-turn to reach summit of Spirit Mound

'Millions' needed to continue Europe's Mars mission: ESA chief

TECH SPACE
Long March-5 reflects China's "greatest advancement" yet in rockets

New heavy-lift carrier rocket boosts China's space dream

Long March-7 being assembled, to transport Tianzhou-1

Kuaizhou-1 scheduled to launch in December

TECH SPACE
AsiaSat wins patent for effective satellite broadband connectivity to aircraft

Sun-observing MinXSS CubeSat to yield insights into solar flare energetics

Optus achieves full certification of 4 teleports

ISRO's World record bid: Launching 83 satellites on single rocket

TECH SPACE
We gather here today to join lasers and anti-lasers

Trace metal recombination centers kill LED efficiency

Studying structure to understand function within 'material families'

Study: Math scares everyone, even physicists

TECH SPACE
What happens to a pathogenic fungus grown in space?

How Planets Like Jupiter Form

Giant Rings Around Exoplanet Turn in the Wrong Direction

Preferentially Earth-sized Planets with Lots of Water

TECH SPACE
Mystery solved behind birth of Saturn's rings

Last Bits of 2015 Pluto Flyby Data Received on Earth

Uranus may have two undiscovered moons

Possible Clouds on Pluto, Next Target is Reddish




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News






The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement