Subscribe free to our newsletters via your
. 24/7 Space News .

Subscribe free to our newsletters via your

Elusive atomic motion captured by electron microscopy
by Staff Writers
Linkoping, Sweden (SPX) May 16, 2017

The researchers at Linkoping University used scanning transmission electron microscopy to study diffusion in thin film. Credit Karin Soderlund Leifler

The movement of atoms through a material can cause problems under certain circumstances. Atomic-resolution electron microscopy has enabled researchers at Linkoping University in Sweden to observe for the first time a phenomenon that has eluded materials scientists for many decades. The study is published in Scientific Reports.

In some contexts, it is extremely important that boundaries are maintained. One example is within thin film technology, which uses extremely thin films of various materials stacked on top of each other. The thermally induced movement of atoms through a material, diffusion, is well-known.

A specific sort of diffusion along linear defects in a material was proposed as early as the 1950s, but has remained a theoretical concept since then and researchers have never been able to observe it directly. Instead, theoretical models and indirect methods are commonly applied to measure that phenomenon, known as dislocation-pipe diffusion.

Researchers at Linkoping University and the University of California in Berkeley have now finally been able to observe the migration of atoms between the layers of a thin film. They used scanning transmission electron microscopy (STEM) with such a high resolution that it was possible to image the positions of individual atoms in the material. The specimen they studied was a thin film in which layers of a metal, hafnium nitride (HfN), around 5 billionths of a metre thick, alternate with layers of a semiconductor, scandium nitride (ScN).

The properties of the HfN/ScN layers make this material a suitable candidate for use in, for example, coating technology and microelectronics. It is for stability reasons very important that the layers of metal and semiconductor do not mix. Problems arise if the atoms diffuse across an interlayer forming a closed bridge between the layers in the film, similar to an electric short circuit.

"The material we have studied acts as a perfect model system, but this type of diffusion occurs in nearly all materials. Metals and semiconductors are found in all the electronic components used in in mobile phones, computers, etc. This is why it is important that materials scientists understand this type of diffusion," says Magnus Garbrecht, associate senior lecturer in the Department of Physics, Chemistry and Biology at Linkoping University.

The discovery described in the article came about when Magnus Garbrecht heated HfN/ScN to 950 C. He noticed that the hafnium was diffusing down into the underlying layers. It turned out that a defect was present in the material where this phenomenon arose. The researchers heated the material several times and subsequently examined it using STEM and measured how far individual atoms moved.

"The values we measured agree well with those from previous experiments using indirect methods and with the theoretical models, and this makes us confident that what we are seeing really is dislocation-pipe diffusion," says Magnus Garbrecht.

The researchers provide an explanation why the atoms diffuse when the material is heated. The individual atoms are slightly displaced relative to each other in the regions around the linear defects. The atoms tend to arrange themselves in a perfect cubic symmetry, and strain builds up within the lattice when this arrangement is disturbed. The researchers show in the study that this strain relaxes as the atoms diffuse.

"The diffusion reduces the strain in the material and this is why it only occurs along the linear defects threading through the material," says Magnus Garbrecht.

The article: Dislocation-pipe diffusion in nitride superlattices observed in direct atomic resolution, Magnus Garbrecht, Bivas Saha, Jeremy L. Schroeder, Lars Hultman, Timothy D. Sands, Scientific Reports, published online on 6 April 2017, doi: 10.1038/srep46092

'Fire-streaks' are created in collisions of atomic nuclei
Warsaw, Poland (SPX) May 12, 2017
At very high energies, the collision of massive atomic nuclei in an accelerator generates hundreds or even thousands of particles that undergo numerous interactions. At the Institute of Nuclear Physics of the Polish Academy of Sciences in Cracow, Poland it has been shown that the course of this complex process can be represented by a surprisingly simple model: extremely hot matter moves away fro ... read more

Related Links
Linkoping University
Understanding Time and Space

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 DiggDigg RedditReddit GoogleGoogle

'Awesomesauce,' proclaims US astronaut on historic spacewalk

Six-legged livestock - sustainable food production

External commercial ISS platform starts second mission

NASA Receives Proposals for Future Solar System Mission

SpaceX launches Inmarsat communications satellite

Testing Prepares NASA's Space Launch System for Liftoff

N. Korea's 'new missile' has unprecedented range: experts

NASA Affirms Plan for First Mission of SLS, Orion

Opportunity Reaches 'Perseverance Valley'

Ancient Mars impacts created tornado-like winds that scoured surface

Mars Rover Opportunity Begins Study of Valley's Origin

Seasonal Flows in Valles Marineris

A cabin on the moon? China hones the lunar lifestyle

China tests 'Lunar Palace' as it eyes moon mission

China to conduct several manned space flights around 2020

Reach for the Stars: China Plans to Ramp Up Space Flight Activity

Allied Minds' portfolio company BridgeSat raises $6 million in Series A financing

AIA report outlines policies needed to boost the US Space Industry competitiveness

Blue Sky Network Targets Key Markets For Iridium SATCOM Solutions

How Outsourcing Your Satellite Related Services Saves You Time and Money

"Airbus Friedrichshafen: new satellite hub lays groundwork for the future"

Physics may bring faster solutions for tough computational problems

A bath for precision printing of 3-D silicone structures

Physical keyboards make virtual reality typing easier

'Warm Neptune' Has Unexpectedly Primitive Atmosphere

Astrophysicists find that planetary harmonies around TRAPPIST-1 save it from destruction

Two Webb instruments well suited for detecting exoplanet atmospheres

Variable Winds on Hot Giant Exoplanet Help Study of Magnetic Field

Waves of lava seen in Io's largest volcanic crater

Not So Great Anymore: Jupiter's Red Spot Shrinks to Smallest Size Ever

The PI's Perspective: No Sleeping Back on Earth!

ALMA investigates 'DeeDee,' a distant, dim member of our solar system

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