Featured Research

from universities, journals, and other organizations

Researchers Spy Galfenol's Inner Beauty Mark

Date:
April 3, 2009
Source:
National Institute of Standards and Technology (NIST)
Summary:
Scientists have figured out why an alloy developed by the military over a decade ago behaves the way it does -- it's because of sprinkling of useful imperfections within an otherwise regular crystal. The new information on Galfenol could lead to more sensitive sonar equipment for submarines and other improved sensors.

Magnetostrictors are a critical element in sound detection equipment including the sonar used in submarines. Scientists working at NIST solved the structure of the magnetostrictor Galfenol, which could improve sonar's capabilities in the future.
Credit: U.S. Navy photo

The sonar on submarines may get far more sensitive ears in the near future thanks to a mysterious compound developed by the military. Developed over a decade ago, it took a collaboration of scientists from the Virginia Polytechnic Institute and State University and the National Institute of Standards and Technology (NIST) to determine why the material works. Surprisingly, the critical factor is a sprinkling of useful imperfections within an otherwise regular crystal.

The scientific team solved the internal structure of Galfenol, a compound of iron and gallium that changes shape when exposed to a magnetic field. Because the effect also works in reverse—a tiny bit of pressure that distorts its shape slightly and induces detectable magnetism—such “magnetostrictors” are the key ingredients in sound detection equipment.

Iron alone has some talent as a magnetostrictor, but U.S. Navy researchers discovered in 1998 that doping iron with gallium amplifies iron’s magnetostrictive capability tenfold. They dubbed their creation Galfenol, but the basis for the material’s behavior went unexplained.

“It’s important to know why a material works the way it does,” says Peter Gehring of the NIST Center for Neutron Research (NCNR). “If you can relate its atomic structure to its behavior, you might be able to improve the recipe.”

The scientists used neutron beams to determine Galfenol’s structure, settling a running debate over which model of its innards was correct. The investigation showed that the added gallium changes the structure of the iron, which on the atomic level forms a lattice of regular cubic cells. When the gallium combines with the iron, the faces of some cells become rectangular rather than square. These elongated gallium-iron cells then congregate into tiny clumps within the lattice, resembling “something like raisins within a cake,” as Gehring describes it.

The study also showed that these clusters of distorted cells respond to a magnetic field by rotating their magnetic moments, like tiny compass needles, to align with the field; it is this rotation that changes the exterior dimensions of the crystal. The clusters are thus responsible for Galfenol’s performance—it changes in size by 400 parts per million compared to iron’s 30—even though it seems surprising that imperfections in iron’s otherwise orderly lattice should improve its magnetostrictive talents.

“These irregularities give the iron more complex and richer properties,” Gehring says. “We see this theme repeated frequently in nature, where similar kinds of disorder lead to improved performance in high-temperature superconductors, giant magnetoresistive oxides, and other exotic new materials. It’s like the supermodel with a beauty mark on her cheek—we don’t know why it’s so appealing, but it is."

The study was funded in part by the Office of Naval Research.


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology (NIST). Note: Materials may be edited for content and length.


Journal Reference:

  1. H. Cao, P.M. Gehring, C.P. Devreugd, J.A. Rodriguez-Rivera, J. Li and D. Viehland. The role of nano-scale precipitates on the enhanced magnetostriction of heat-treated Galfenol (Fe1-xGax). Physical Review Letters, 2009; (forthcoming)

Cite This Page:

National Institute of Standards and Technology (NIST). "Researchers Spy Galfenol's Inner Beauty Mark." ScienceDaily. ScienceDaily, 3 April 2009. <www.sciencedaily.com/releases/2009/03/090325132338.htm>.
National Institute of Standards and Technology (NIST). (2009, April 3). Researchers Spy Galfenol's Inner Beauty Mark. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2009/03/090325132338.htm
National Institute of Standards and Technology (NIST). "Researchers Spy Galfenol's Inner Beauty Mark." ScienceDaily. www.sciencedaily.com/releases/2009/03/090325132338.htm (accessed October 21, 2014).

Share This



More Matter & Energy News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Thanks, Marty McFly! Hoverboards Could Be Coming In 2015

Thanks, Marty McFly! Hoverboards Could Be Coming In 2015

Newsy (Oct. 21, 2014) If you've ever watched "Back to the Future Part II" and wanted to get your hands on a hoverboard, well, you might soon be in luck. Video provided by Newsy
Powered by NewsLook.com
Robots to Fly Planes Where Humans Can't

Robots to Fly Planes Where Humans Can't

Reuters - Innovations Video Online (Oct. 21, 2014) Researchers in South Korea are developing a robotic pilot that could potentially replace humans in the cockpit. Unlike drones and autopilot programs which are configured for specific aircraft, the robots' humanoid design will allow it to fly any type of plane with no additional sensors. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Graphene Paint Offers Rust-Free Future

Graphene Paint Offers Rust-Free Future

Reuters - Innovations Video Online (Oct. 21, 2014) British scientists have developed a prototype graphene paint that can make coatings which are resistant to liquids, gases, and chemicals. The team says the paint could have a variety of uses, from stopping ships rusting to keeping food fresher for longer. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
China Airlines Swanky New Plane

China Airlines Swanky New Plane

Buzz60 (Oct. 21, 2014) China Airlines debuted their new Boeing 777, and it's more like a swanky hotel bar than an airplane. Enjoy high-tea, a coffee bar, and a full service bar with cocktails and spirits, and lie-flat in your reclining seats. Sean Dowling (@SeanDowlingTV) has the details. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins