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




Subscribe to our free daily newsletters



TECH SPACE
New insights into atomic disordering of complex metal oxides
by Staff Writers
Oak Ridge TN (SPX) Mar 18, 2016


Defect fluorite materials such as Ho2Zr2O7 have been previously characterized as having a disordered cubic structure when sampled over many unit cell repeats. However, (a) pair distribution functions obtained from neutron total scattering reveals that description is inaccurate at the sub-nanometer level. Instead, (b) the local structure can be accurately modeled with an orthorhombic, weberite-type configuration revealing a complex disordering mechanism in these oxides, operating over different length scales. Image courtesy ORNL. For a larger version of this image please go here.

A study led by the University of Tennessee and the Department of Energy's Oak Ridge National Laboratory could soon pay dividends in the development of materials with energy-related applications.

Three UT researchers - Maik Lang, assistant professor of nuclear engineering; Haidong Zhou, assistant professor of physics; and Jacob Shamblin, a graduate research assistant in nuclear engineering and physics - studied an important class of complex metal oxides.

The materials, each consisting of two or more positively charged metal ions and oxygen, are used in a wide range of applications including fast ion conductors in solid oxide fuel cells, host materials for nuclear waste containment, and thermal barrier coatings for gas turbine jet engines.

For their study, the team used state-of-the-art neutron characterization techniques to gain a detailed understanding and new insights into the nature of the atomic motifs in these materials. The work was published in the journal Nature Materials on February 29.

"The complex oxides we analyzed in this study - pyrochlore and spinel - have been investigated for decades by different researchers," said Lang. "When subjected to extreme environments such as high temperatures or high-energy radiation, many of these compounds partially lose their long-range crystal structure, and the multiple cations were thought to randomly exchange crystal sites."

Lang said the multidisciplinary research team and the unique capabilities of ORNL's Spallation Neutron Source, a DOE Office of Science User Facility, helped the team discover a novel atomic disordering mechanism in these materials.

With the help of SNS instrument scientists Mikhail Feygenson and Joerg Neuefeind, Lang and his team used the Nanoscale-Ordered Materials Diffractometer (NOMAD) for an in-depth look at the local crystal structure of their samples - a NOMAD first for neutron scattering experiments on ion-irradiated materials.

Neutrons are indispensable for this type of study because they can accurately detect the position of oxygen atoms present in materials.

"Using neutrons to measure samples of such small sizes would have been difficult, if not impossible, just a few years ago," said Feygenson. "However, with the combination of the high neutron flux of SNS and the wide detector coverage of the NOMAD instrument, scientists can look at very small samples, which are typically the domain of X-ray scattering experiments."

Data analysis from NOMAD revealed the cations and oxygens in the materials are not randomly arranged at the atomic level but only appear so when sampling over longer scales, a key discovery.

Lang said the heterogeneous disorder was unexpected but seems to be a general phenomenon for many other materials functioning in harsh conditions. He said the new insight into disorder is fundamental to controlling oxygen mobility and phonon transport in complex oxides, a critical aspect for technological applications.

By gaining a better understanding of such materials, the team could help improve and control performance across a range of technologies - containment and immobilization of nuclear waste being a prime example.

"This ability to accommodate atomic disorder in their structure accounts for the tendency of some compositions to resist becoming fully amorphous under irradiation or at high temperatures," Lang said. "Such materials find application as host materials for immobilizing actinides, such as plutonium.

"Predicting transport of radionuclides is important for their safe use as nuclear waste forms and requires a detailed knowledge of how the atomic structure responds to self-irradiation."

Lang said the team's data will provide much needed atomic-scale information from the initial local defect structure to the long-range observable material modifications so that waste form properties and degradation can be accurately simulated.

Other researchers on the team included Cameron Tracy and Rodney Ewing of Stanford University, Fuxiang Zhang of the University of Michigan, and Sarah Finkeldei and Dirk Bosbach of the Forschungszentrum Julich Institute of Energy and Climate Research in Germany. The paper can be found here


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
Oak Ridge National Laboratory
Space Technology News - Applications and Research






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

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

Previous Report
TECH SPACE
ORNL researchers stack the odds for novel optoelectronic 2-D materials
Oak Ridge TN (SPX) Mar 14, 2016
Stacking layers of nanometer-thin semiconducting materials at different angles is a new approach to designing the next generation of energy-efficient transistors and solar cells. The atoms in each layer are arranged in hexagonal arrays. When two layers are stacked and rotated, atoms from one layer overlap with those in the other layer and can form an infinite number of overlapping patterns, like ... read more


TECH SPACE
Permanent Lunar Colony Possible in 10 Years

China to use data relay satellite to explore dark side of moon

NASA May Return to Moon, But Only After Cutting Off ISS

Lunar love: When science meets artistry

TECH SPACE
ExoMars probe imaged en route to Mars

How the ExoMars mission could sniff out life on Mars

ExoMars on its way to solve the Red Planet's mysteries

Europe's New Mars Mission Bringing NASA Radios Along

TECH SPACE
Space travel rules needed within 5 years: UN

Jacobs Joins Coalition for Deep Space Exploration

Space Race Competition helps turn NASA Tech into new products

Broomstick flying or red-light ping-pong? Gadgets at German fair

TECH SPACE
China to establish first commercial rocket launch company

China's ambition after space station

Sky is the limit for China's national strategy

Aim Higher: China Plans to Send Rover to Mars in 2020

TECH SPACE
Grandpa astronaut to break Scott Kelly's space record

Three new members join crew of International Space Station

Three new crew, including US grandpa, join space station

Space station astronauts ham it up to inspire student scientists

TECH SPACE
ILS and INMARSAT Agree To Future Proton Launch

Soyuz 2-1B Carrier Rocket Launched From Baikonur

Launch of Dragon Spacecraft to ISS Postponed Until April

ISRO launches PSLV C32, India's sixth navigation satellite

TECH SPACE
VLA observes earliest stages of planet formation

NASA's K2 mission: Kepler second chance to shine

Star eruptions create and scatter elements with Earth-like composition

Astronomers discover two new 'hot Jupiter' exoplanets

TECH SPACE
Outsourcing crystal growth...to space

International research team achieves controlled movement of skyrmions

Light helps the transistor laser switch faster

UA's Space Expertise Seen as Key for US Security




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