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




Subscribe to our free daily newsletters



TECH SPACE
Two-dimensional materials gets a new theory for control of properties
by Staff Writers
University Park PA (SPX) Oct 20, 2017


A grain boundary forms when graphene growth advances past an apex on a conical bump, where the curvature resembles that on a sphere; it terminates at the foot of the bump, where curvature is saddle-like.

Desirable properties including increased electrical conductivity, improved mechanical properties, or magnetism for memory storage or information processing may be possible because of a theoretical method to control grain boundaries in two-dimensional materials, according to Penn State materials scientists.

Two-dimensional (2D) materials have been the focus of intense study in the last decade, but prior to the work of Yuanxi Wang, a recent Penn State doctoral graduate and Vincent H. Crespi, distinguished professor of physics, materials science and engineering and chemistry at Penn State, no one had devised a general way to control the location and type of grain boundaries in 2D materials.

"When you are growing a 2D material, a thin film, you are depositing materials on a substrate," Crespi explained. "As the atoms fall onto the substrate, they self-organize into crystalline areas called grains."

When the grains expand, they run into other growing crystalline regions, and where they meet is called the grain boundary. But like tiling a floor by tossing the tiles randomly, the orientation of the grains and grain boundaries are arbitrary, which affects the material properties.

Until this work, published in the journal Nano Letters, these random grain boundaries were largely considered to be unfortunate byproducts of the deposition process.

"Typically, when you are growing a material, those random grain boundaries are bad," said Crespi. "The atoms don't mate to each other the way they do in ordinary crystals. Current and heat don't pass through easily. They tend to scatter heat and electrons."

Crespi and Wang had the idea that by manipulating the underlying substrate, they could predetermine where the grain boundaries would begin and end, and make them line up in orderly positions. The key shapes were based on something called Gaussian curvature, a series of hemispherical bumps and dips on a substrate that resembles an egg carton.

Wang did calculations that showed that for two widely studied 2D materials, graphene and molybdenum disulfide, the growth would form grain boundaries in specific locations rather than detaching from the substrate or developing unwanted folds. If the 2D material does not adhere well to the substrate, it will generate a fold.

"We found that the energetics and kinetics of forming grain boundaries versus a fold or detachment, were favorable in graphene and molybdenum disulfide, and applicable to any 2D material," Wang said. "But not any bump would do. They have to have Gaussian curvature."

Applications include memory storage, where controlling the magnetic state of a 2D magnetic-grain boundary system by applying a voltage would be a very useful capability. The fine control of electronic properties via grain boundaries might also be used in spintronics, which is processing information using the spin of electrons. These grain boundaries also often control the mechanical properties of materials, such as how they respond under stretching.

"This gives people a new way of thinking about optimizing the properties of 2D materials where they have more control than previously," Crespi said. "We didn't know we could have such fine control of grain boundaries, and so we didn't think about carefully studying the magnetic, thermal and electronic properties of grain boundaries with an eye toward creating 'grain boundary materials' whose properties are determined by a controlled distribution of specified grain boundaries."

TECH SPACE
Study shows how rough microparticles can cause big problems
Raleigh NC (SPX) Oct 18, 2017
New research from North Carolina State University, MIT and the University of Michigan finds that the surface texture of microparticles in a liquid suspension can cause internal friction that significantly alters the suspension's viscosity - effectively making the liquid thicker or thinner. The finding can help address problems for companies in fields from biopharmaceuticals to chemical manufactu ... read more

Related Links
Penn State
Space Technology News - Applications and Research


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

Comment using your Disqus, Facebook, Google or Twitter login.

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

TECH SPACE
Plants and psychological well-being in space

Russia's space agency says glitch in manned Soyuz landing

Russia launches cargo ship to space station

Roscosmos: International Space Exploration to Continue Despite Geopolitical Situation

TECH SPACE
ESA role in Europe's first all-electric telecom satellite

Lockheed Martin Launches Second Cycle of 'Girls' Rocketry Challenge' in Japan

First Four Space Launch System Flight Engines Ready To Rumble

Rocket motor for Ariane 6 and Vega-C is cast for testing

TECH SPACE
Solar eruptions could electrify Martian moons

MAVEN finds Mars has a twisted tail

A mission to Mars could make its own oxygen thanks to plasma technology

Study shows how water could have flowed on 'cold and icy' ancient Mars

TECH SPACE
China launches three satellites

Mars probe to carry 13 types of payload on 2020 mission

UN official commends China's role in space cooperation

China's cargo spacecraft separates from Tiangong-2 space lab

TECH SPACE
Eutelsat's Airbus-built full electric EUTELSAT 172B satellite reaches geostationary orbit

Turkey, Russia to Enhance Cooperation in the Field of Space Technologies

SpaceX launches 10 satellites for Iridium mobile network

Lockheed Martin Completes First Flexible Solar Array for LM 2100 Satellite

TECH SPACE
The drop that's good to the very end

Study shows how rough microparticles can cause big problems

Chemical treatment improves quantum dot lasers

Missing link between new topological phases of matter discovered

TECH SPACE
New NASA study improves search for habitable worlds

A star that devoured its own planets

Astronomers find potential solution into how planets form

Giant Exoplanet Hunters: Look for Debris Disks

TECH SPACE
Haumea, the most peculiar of Pluto companions, has a ring around it

Ring around a dwarf planet detected

Helicopter test for Jupiter icy moons radar

Solving the Mystery of Pluto's Giant Blades of Ice




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