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




Subscribe to our free daily newsletters



TECH SPACE
Explaining how 2-D materials break at the atomic level
by Staff Writers
Seoul, South Korea (SPX) Jan 20, 2017


Schematic representation of the crack propagation in 2-D MoS2 at the atomic level. Dislocations shown with red and purple dots are visible at the crack tip zone. Internal tensile stresses are represented by red arrows. Image courtesy IBS.

Cracks sank the 'unsinkable' Titanic; decrease the performance of touchscreens and erode teeth. We are familiar with cracks in big or small three-dimensional (3D) objects, but how do thin two-dimensional (2D) materials crack? 2D materials, like molybdenum disulfide (MoS2), have emerged as an important asset for future electronic and photoelectric devices.

However, the mechanical properties of 2D materials are expected to differ greatly from 3D materials. Scientists at the Center for Integrated Nanostructure Physics (CINAP), within the Institute for Basic Science (IBS) published, on Nature Communications, the first observation of 2D MoS2 cracking at the atomic level. This study is expected to contribute to the applications of new 2D materials.

Obviously when a certain force is applied to a material a crack is created. Less obvious is how to explain and predict the shape and seriousness of a crack from a physics point of view. Scientists want to investigate which fractures are likely to expand and which are not .Materials are divided into ductile and brittle: Ductile materials, like gold, withstand large strains before rupturing; brittle materials, like glass, can absorb relatively little energy before breaking suddenly, without elongation and deformation.

At the nano-level atoms move freer in ductile materials than in brittle materials; so in the presence of a pulling force (tensile stress) they can go out of position from the ordered crystal structure, or in technical terms - they dislocate. So far, this explanation (Griffith model) has been applied to cracking phenomena in bulk, but it lacks experimental data at the atomic or nano-scale.

In this study, IBS scientists observed how cracks propagate on 2D MoS2 after a pore was formed either spontaneously or with an electron beam. "The most difficult point {of the experiments} was to use the electron beam to create the pore without generating other defects or breaking the sample," explains Thuc Hue Ly, first author of this study. "So we had to be fast and use a minimum amount of energy."

The atomic observations were done using real-time transmission electron microscopy. Surprisingly, even though MoS2 is a brittle material, the team saw atom dislocations 3-5 nanometers (nm) away from the front line of the crack, or crack tip. This observation cannot be explained with the Griffith model.

In order to create conditions that represent the natural environment, the sample was exposed to ultraviolet (UV) light. This caused the MoS2 to oxidize; atom dislocations occurred more rapidly and the stretched region expanded to 5-10 nm from the crack tip.

"The study shows that cracking in 2D materials is fundamentally different from cracking in 3D ductile and brittle materials. These results cannot be explained with the conventional material failure theory, and we suggest that a new theory is needed," explained Professor LEE Young Hee (CINAP).

Cracks sank the 'unsinkable' Titanic; decrease the performance of touchscreens and erode teeth. We are familiar with cracks in big or small three-dimensional (3D) objects, but how do thin two-dimensional (2D) materials crack? 2D materials, like molybdenum disulfide (MoS2), have emerged as an important asset for future electronic and photoelectric devices. However, the mechanical properties of 2D materials are expected to differ greatly from 3D materials.

Scientists at the Center for Integrated Nanostructure Physics (CINAP), within the Institute for Basic Science (IBS) published, on Nature Communications, the first observation of 2D MoS2 cracking at the atomic level. This study is expected to contribute to the applications of new 2D materials.

Obviously when a certain force is applied to a material a crack is created. Less obvious is how to explain and predict the shape and seriousness of a crack from a physics point of view. Scientists want to investigate which fractures are likely to expand and which are not .Materials are divided into ductile and brittle: Ductile materials, like gold, withstand large strains before rupturing; brittle materials, like glass, can absorb relatively little energy before breaking suddenly, without elongation and deformation.

At the nano-level atoms move freer in ductile materials than in brittle materials; so in the presence of a pulling force (tensile stress) they can go out of position from the ordered crystal structure, or in technical terms - they dislocate. So far, this explanation (Griffith model) has been applied to cracking phenomena in bulk, but it lacks experimental data at the atomic or nano-scale.

In this study, IBS scientists observed how cracks propagate on 2D MoS2 after a pore was formed either spontaneously or with an electron beam. "The most difficult point {of the experiments} was to use the electron beam to create the pore without generating other defects or breaking the sample," explains Thuc Hue Ly, first author of this study. "So we had to be fast and use a minimum amount of energy."

The atomic observations were done using real-time transmission electron microscopy. Surprisingly, even though MoS2 is a brittle material, the team saw atom dislocations 3-5 nanometers (nm) away from the front line of the crack, or crack tip. This observation cannot be explained with the Griffith model.

In order to create conditions that represent the natural environment, the sample was exposed to ultraviolet (UV) light. This caused the MoS2 to oxidize; atom dislocations occurred more rapidly and the stretched region expanded to 5-10 nm from the crack tip.

"The study shows that cracking in 2D materials is fundamentally different from cracking in 3D ductile and brittle materials. These results cannot be explained with the conventional material failure theory, and we suggest that a new theory is needed," explained Professor LEE Young Hee (CINAP).

Research paper


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
Institute for Basic Science
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
The power of attraction
Thuwal, Saudi Arabia (SPX) Jan 18, 2017
Engineered nanometer- and micrometer-scale structures have a vast array of uses in electronics, sensors and biomedical applications. Because these are difficult to fabricate, KAUST researchers are trying a bottom-up philosophy, which harnesses the natural forces between atoms and molecules such that microstructures form themselves. This approach, a departure from the usual top-down approac ... read more


TECH SPACE
NASA to rely on Soyuz for ISS missions until 2019

Mister Trump Goes to Washington

Lomonosov Moscow State University to Launch 'Space Department' in 2017

French, US astronauts install batteries outside space station

TECH SPACE
When One launch is not enough: SpaceX Return To Flight

Airbus Safran Launchers in 2016: we keep our promises

2017 Rocket Campaign Begins in Alaska

India Defers Much-Awaited Heaviest Rocket Launch

TECH SPACE
Long Eclipse Avoidance Manoeuvres Performed Successfully on MOM Spacecraft

Microbes could survive thin air of Mars

Mars rover Opportunity takes a drive up a steep slope

Mars Rover Curiosity Examines Possible Mud Cracks

TECH SPACE
China's first cargo spacecraft to leave factory

China launches commercial rocket mission Kuaizhou-1A

China Space Plan to Develop "Strength and Size"

Beijing's space program soars in 2016

TECH SPACE
Shaping the Future: Aerospace Works to Ensure an Informed Space Policy

Iridium-1 NEXT Launched on a Falcon 9

Russia-China Joint Space Studies Center May Be Created in Southeastern Russia

EchoStar 19 positioned in orbital slot

TECH SPACE
Explaining how 2-D materials break at the atomic level

China's quantum communication satellite delivered for use

First European-built all-electric satellite EUTELSAT 172B getting ready to fly

The power of attraction

TECH SPACE
SF State astronomer searches for signs of life on Wolf 1061 exoplanet

Looking for life in all the right places with the right tool

Could dark streaks in Venusian clouds be microbial life

VLT to Search for Planets in Alpha Centauri System

TECH SPACE
Public to Choose Jupiter Picture Sites for NASA Juno

Experiment resolves mystery about wind flows on Jupiter

Pluto Global Color Map

Lowell Observatory to renovate Pluto discovery telescope




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