Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Scientists Customize a Magnetís Performance by Strategically Replacing Key Atoms

Abstract:
The work could lead to improved methodologies for creating materials by design

Scientists Customize a Magnetís Performance by Strategically Replacing Key Atoms

Ames, IO | Posted on February 3rd, 2011

Scientists have given us a plethora of new materials - all created by combining individual elements under varying temperatures and other conditions. But to tweak an intermetallic compound even more, in order to give it the attributes you desire, you have to go deeper and re-arrange individual atoms.

It's a process similar to what bioengineers employ when they add and delete genes to create synthetic organisms, and it was the focus of a group of researchers at the U.S. Department of Energy's Ames Laboratory, when they replaced key atoms in a gadolinium-germanium magnetic compound with lutetium and lanthanum atoms.

The group was led by Vitalij Pecharsky, Ames Lab senior scientist and Distinguished Professor of Materials Science and Engineering at Iowa State University, and included his Lab colleagues, Karl Gschneidner Jr., Ames Lab senior metallurgist and Distinguished Professor of MS&E at ISU, and Gordon Miller, Ames Lab senior scientist and ISU professor of chemistry, along with assistant scientists Yaroslav Mudryk and Durga Paudyal. Also participating was Sumohan Misra, research associate at the DOE's SLAC National Accelerator in Menlo Park, Calif., formerly a Ph.D. student of Miller's.

Creating materials by design is no easy task, especially in the case of the complex gadolinium-germanium - Gd5Ge4 - compound. Making things even more difficult, the compound's structure is highly symmetrical, which is common in intermetallics, so predicting which atoms are key to changing the material's characteristics would be difficult if not impossible unless some methodology was available to help in the selection process.

The Gd5Ge4 compound's uniformity results from the fact that like nearly all metallic solids' atoms are arranged in a highly symmetrical crystal structure called a lattice. The more complex the material, the more intricate its lattice. And while the individual elements making up the lattice influence its characteristics, in some cases the location of specific atoms within the lattice can also have a profound influence on such things as its melting point, mechanical strength or - in the case of magnets - ferromagnetic properties.

"Individuality doesn't happen often among the atoms of metallic crystals," Pecharsky explained, "But atoms still are able to Ďcooperate' with one another in areas such as magnetic ordering and superconductivity."

By discovering these cooperative relationships, scientists can determine what will happen if they replace one or more of the atoms with those of another element, which is precisely what the team accomplished.

"We revealed that a single site occupied by the Gd atoms is much more active than all of the other Gd sites when it comes to bringing the ferromagnetic order in a complex crystal structure of gadolinium germanide," Pecharsky said.

Pecharsky, Gschneidner and other researchers at the Ames Lab have spent years working with gadolinium alloys, because of the magnetic compound's use in the green, energy-saving field of magnetic refrigeration. However, that was not the main reason the Ames Lab researchers chose Gd5Ge4 for their work.

As it turns out, "the metal exhibits an impressive combination of intriguing and potentially important properties, the researchers explained in their paper, "Controlling Magnetism of a Complex Metallic System Using Atomic Individualism," published in the August 10, 2010 Physical Review Letters. "The extraordinary responsiveness to relatively weak external stimuli makes Gd5Ge4 and related compounds a phenomenal playground for condensed matter science."

Besides being unusually responsive, Gd5Ge4 was an ideal alloy for the work, because any changes in its magnetic properties resulting from the group's manipulations could be easily measured.

In 2008, Pecharsky and members of the same research team had already discovered that adding silicon to the alloy resulted in a magnetostructural transition that occurred without the application of a magnetic field. Chemical pressure alone was able to enhance the material's ferromagnetism.

That earlier finding led the team to experiment with other additions to the alloy. To ferret out precisely which atoms in the lattice were the best candidates for manipulation, the researchers called upon density functional theory, which is a means of studying the electronic structure of solids developed by Nobel Prize winning physicist Walter Kohn.

Kohn's methodology enabled the group to model the effects substituting small amounts of gadolinium atoms within the Gd5Ge4 solid with the elements lutetium and lanthanum. With the modeled results in hand, the group's next step was to create the actual alloys in the lab, in order to test the accuracy of their computer-based predictions.

In fact, the complex fabrication process confirmed the modeling results. The researchers found if they replaced just a few gadolinium atoms with lutetium, the result would be a severe loss in the alloy's ferromagnetism. By contrast, substituting an equal number of lanthanum atoms had no significant effect; though substituting greater amounts of lanthanum might have a more pronounced impact on the resulting alloy's ferromagnetism, the researchers speculated.

Going forward, the lessons learned in this experiment could have important far-reaching implications, as materials scientists search for new exotic substances to be used in this and future generations of high-tech products. "Knowing how to identify key atomic positions is similar to understanding the roles specific genes play in an organism's DNA sequence," Pecharsky said. "And that knowledge could ultimately lead to materials by design."

This research was funded by the DOE Office of Science.

####

About Ames Laboratory
The Ames Laboratory is a U.S. Department of Energy Office of Science research facility operated by Iowa State University. The Ames Laboratory creates innovative materials, technologies and energy solutions. We use our expertise, unique capabilities and interdisciplinary collaborations to solve global problems.

For more information, please click here

Contacts:
Vitalij Pecharsky
Materials Science and Engineering
515-294-8220

Steve Karsjen
Public Affairs
515-294-5643

Copyright © Ames Laboratory

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Nanoscale view of energy storage January 16th, 2017

Seeing the quantum future... literally: What if big data could help you see the future and prevent your mobile phone from breaking before it happened? January 16th, 2017

NUS researchers achieve major breakthrough in flexible electronics: New classes of printable electrically conducting polymer materials make better electrodes for plastic electronics and advanced semiconductor devices January 14th, 2017

Manchester scientists tie the tightest knot ever achieved January 13th, 2017

Govt.-Legislation/Regulation/Funding/Policy

Nanoscale view of energy storage January 16th, 2017

Chemistry on the edge: Experiments at Berkeley Lab confirm that structural defects at the periphery are key in catalyst function January 13th, 2017

Recreating conditions inside stars with compact lasers: Scientists offer a new path to creating the extreme conditions found in stars, using ultra-short laser pulses irradiating nanowires January 12th, 2017

New laser based on unusual physics phenomenon could improve telecommunications, computing January 12th, 2017

Possible Futures

Nanoscale view of energy storage January 16th, 2017

Seeing the quantum future... literally: What if big data could help you see the future and prevent your mobile phone from breaking before it happened? January 16th, 2017

NUS researchers achieve major breakthrough in flexible electronics: New classes of printable electrically conducting polymer materials make better electrodes for plastic electronics and advanced semiconductor devices January 14th, 2017

Nanoscale Modifications can be used to Engineer Electrical Contacts for Nanodevices January 13th, 2017

Academic/Education

Oxford Nanoimaging report on how the Nanoimager, a desktop microscope delivering single molecule, super-resolution performance, is being applied at the MRC Centre for Molecular Bacteriology & Infection November 22nd, 2016

The University of Applied Sciences in Upper Austria uses Deben tensile stages as an integral part of their computed tomography research and testing facility October 18th, 2016

Enterprise In Space Partners with Sketchfab and 3D Hubs for NewSpace Education October 13th, 2016

New Agricultural Research Center Debuts at UCF October 12th, 2016

Materials/Metamaterials

NUS researchers achieve major breakthrough in flexible electronics: New classes of printable electrically conducting polymer materials make better electrodes for plastic electronics and advanced semiconductor devices January 14th, 2017

Manchester scientists tie the tightest knot ever achieved January 13th, 2017

Nanoscale Modifications can be used to Engineer Electrical Contacts for Nanodevices January 13th, 2017

Deciphering the beetle exoskeleton with nanomechanics: Understanding exoskeletons could lead to new, improved artificial materials January 12th, 2017

Announcements

Nanoscale view of energy storage January 16th, 2017

Seeing the quantum future... literally: What if big data could help you see the future and prevent your mobile phone from breaking before it happened? January 16th, 2017

NUS researchers achieve major breakthrough in flexible electronics: New classes of printable electrically conducting polymer materials make better electrodes for plastic electronics and advanced semiconductor devices January 14th, 2017

Nanoscale Modifications can be used to Engineer Electrical Contacts for Nanodevices January 13th, 2017

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project