Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

ORNL finding has materials scientists entering new territory

22.02.2012
Solar cells, light emitting diodes, displays and other electronic devices could get a bump in performance because of a discovery at the Department of Energy's Oak Ridge National Laboratory that establishes new boundaries for controlling band gaps.

While complex transition metal oxides have for years held great promise for a variety of information and energy applications, the challenge has been to devise a method to reduce band gaps of those insulators without compromising the material's useful physical properties.

The band gap is a major factor in determining electrical conductivity in a material and directly determines the upper wavelength limit of light absorption. Thus, achieving wide band gap tunability is highly desirable for developing opto-electronic devices and energy materials.

Using a layer-by-layer growth technique for which Ho Nyung Lee of ORNL earned the Presidential Early Career Award for Scientists and Engineers, Lee and colleagues have achieved a 30 percent reduction in the band gap of complex metal oxides. The findings are outlined in the journal Nature Communications.

"Our approach to tuning band gaps is based on atomic-scale growth control of complex oxide materials, yielding novel artificial materials that do not exist in nature," Lee said. "This 'epitaxy' technique can be used to design entirely new materials or to specifically modify the composition of thin-film crystals with sub-nanometer accuracy."

While band gap tuning has been widely successful for more conventional semiconductors, the 30 percent band gap reduction demonstrated with oxides easily surpasses previous accomplishments of 6 percent – or 0.2 electron volt – in this area and opens pathways to new approaches to controlling band gap in complex-oxide materials.

With this discovery, the potential exists for oxides with band gaps to be continuously controlled over 1 electron volt by site-specific alloying developed by the ORNL team. "Therefore," Lee said, "this work represents a major achievement using complex oxides that offer a number of advantages as they are very stable under extreme and severe environments."

ORNL's Michelle Buchanan, associate lab director for the Physical Sciences Directorate, expanded on Lee's sentiment. "This work exemplifies how basic research can provide technical breakthroughs that will result in vastly improved energy technologies," she said.

Other authors of the paper, titled "Wide band gap tunability in complex transition metal oxides by site-specific substitution," are Woo Seok Choi, Matthew Chisholm, David Singh, Taekjib Choi and Gerald Jellison of ORNL's Materials Science and Technology Division. A patent is pending for this technology.

The research was funded initially by the Laboratory Directed Research and Development program and later by the Department of Energy's Office of Science. Optical measurements were performed in part at the Center for Nanophase Materials Sciences, a DOE-BES user facility at ORNL.

UT-Battelle manages ORNL for the Office of Science. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov/

Ron Walli | EurekAlert!
Further information:
http://www.ornl.gov

More articles from Materials Sciences:

nachricht New biomaterial could replace plastic laminates, greatly reduce pollution
21.09.2017 | Penn State

nachricht Stopping problem ice -- by cracking it
21.09.2017 | Norwegian University of Science and Technology

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The fastest light-driven current source

Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.

Graphene is up to the job

Im Focus: LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.

Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Nerves control the body’s bacterial community

26.09.2017 | Life Sciences

Four elements make 2-D optical platform

26.09.2017 | Physics and Astronomy

Goodbye, login. Hello, heart scan

26.09.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>