Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Physicists Light “Magnetic Fire” to Reveal Energy’s Path

15.05.2013
New York University physicists have uncovered how energy is released and dispersed in magnetic materials in a process akin to the spread of forest fires, a finding that has the potential to deepen our understanding of self-sustained chemical reactions.
The study, which appears in the journal Physical Review Letters, also included researchers from the University of Barcelona, City College of New York, and the University of Florida. It may be downloaded here: http://bit.ly/18FKwFO.

Forest fires spread because an initial flame or spark will heat a substance—a trunk or branch—causing it to burn, which releases heat that causes the fire to spread to other trunks or branches, turning a small spark into a self-sustained, propagating front of fire that can be deadly and is irreversible.

In the Physical Review Letters study, the researchers sought to understand how energy is sustained and spreads in magnetic materials—“magnetic fire.” Such knowledge is important in designing magnetic materials for energy storage applications. This is because magnetic fire can lead to a rapid and uncontrolled release of stored energy, producing significant energy loss in, for example, an electrical generator.

Research on bursts of energy within magnetic systems dates back two decades. But scientists haven’t been able to measure and understand what prompts this phenomenon, known as “magnetic deflagration.”

Part of this mystery lies in the nature of chemical reactions. In such reactions, which produce heat, the energy released is determined by the chemical constituents and cannot be easily varied. What is known as an “activation energy” is typically necessary to start a chemical reaction; energy is then released as the reaction proceeds. In other words, scientists have concluded that a spark is needed to begin this process—much the same way a forest fire begins with a single lit match.

But in magnetic materials the energies can be manipulated by magnetic fields and are therefore very easily varied in an experiment. Thus the activation energy and the energy released are controllable, enabling systematic studies of the physical mechanisms of energy flow.

To achieve this, the researchers surmised they could produce such a “spark” through a series of spins—the chemical equivalent of striking a match. In this case, they employed small single crystals of a molecular magnet— each magnetic molecule being just one billionth of a meter—that could be magnetized, much like the needle of a compass. The researchers provided a pulse of heat as the spark, causing molecular spins near the heaters to flip in a magnetic field, a process that released energy and transmitted it to nearby material.

“When the molecules’ spins are aligned opposite the applied field direction, they possess a high level of energy,” explained Andrew Kent, a professor in NYU’s Department of Physics and the study’s senior researcher. “And then when the spins ‘flip,’ energy is released and dispersed into surrounding magnetic material that can cause a runaway reaction.”

Moreover, the scientists were able to control the speed of this process by adjusting the make-up of the magnetic field in their experiments. Through this detailed examination, they could see under what conditions energy is released and how it propagates.

“These are exciting results and ones that have prompted us to further consider whether a spark is even necessary to start a magnetic fire,” added Kent. “We hope to observe and study situations in which the fire starts spontaneously, without a spark.”

The study was conducted at NYU by Pradeep Subedi and Saul Velez, both doctoral candidates, as well as Ferran Macia, a postdoctoral researcher, and included: Shiqi Li, a City College of New York (CCNY) doctoral candidate; Myriam Sarachik, a professor at CCNY; Javier Tejada, a professor at the University of Barcelona; Shreya Mukherjee, a University of Florida doctoral candidate; and George Christou, a professor at University of Florida.

The research was supported by a grant from the National Science Foundation’s Division of Materials Research (DMR-1006575, DMR-0451605) and Division of Chemistry (CHE-0910472).

James Devitt | EurekAlert!
Further information:
http://www.nyu.edu

More articles from Materials Sciences:

nachricht Strange but true: Turning a material upside down can sometimes make it softer
20.10.2017 | Universitat Autonoma de Barcelona

nachricht Metallic nanoparticles will help to determine the percentage of volatile compounds
20.10.2017 | Lomonosov Moscow State University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>