Featured Research

from universities, journals, and other organizations

A New Understanding Of Crystal Structure Of Actinide Metals

Date:
June 7, 2007
Source:
DOE/Lawrence Livermore National Laboratory
Summary:
Researchers have a better understanding of how the crystal structure of some metals becomes stable through magnetism. Magnetic stabilization of the crystal structures of metals is rare. In some metals, such as manganese, iron, and cobalt, the magnetic interaction energy is large enough to influence the crystal structure.

Researchers from of Lawrence Livermore and Oak Ridge national laboratories and Daresbury Laboratory in the United Kingdom, probed the electronic and magnetic structure of Cm by using electron energy-loss spectroscopy in a transmission electron microscope, electron atomic calculations and density functional theory.
Credit: Image courtesy of DOE/Lawrence Livermore National Laboratory

Researchers have a better understanding of how the crystal structure of some metals becomes stable through magnetism.

Magnetic stabilization of the crystal structures of metals is rare. In some metals, such as manganese, iron, and cobalt, the magnetic interaction energy is large enough to influence the crystal structure.

However, recent research shows that magnetically stabilized crystal structures also include the heavy actinide element, curium (Cm). In a diamond-anvil cell study, Cm was pressurized up to one million atmospheres of pressure, which caused the metal to undergo transformations between five different crystal phases.

But a new study by Livermore scientists goes one step further. The team, made up researchers from of Lawrence Livermore and Oak Ridge national laboratories and Daresbury Laboratory in the United Kingdom, probed the electronic and magnetic structure of Cm by using electron energy-loss spectroscopy (EELS) in a transmission electron microscope (TEM), electron atomic calculations and density functional theory (DFT).

To date absorption-type experiments have not been performed on americium (Am) or Cm.

“Our results for curium go a long way in teaching us a general understanding of how this mechanism occurs,” said Kevin Moore, the LLNL lead author of the research paper that appears in the June 8 issue of the journal Physical Review Letters.  Other Livermore researchers include Mark Wall, Adam Schwartz and Per Sφderlind as well as Gerrit van der Laan from Daresbury and Richard Haire from Oak Ridge.

The Hund’s rule coupling is the key to producing the large spin polarization that dictates the newly found crystal structure of Cm under pressure.

Hund’s rule of maximum spin multiplicity is a principle of atomic chemistry, which assumes that a greater total spin state usually makes the resulting atom more stable, most commonly exhibited in a lower energy state, because it forces the unpaired electrons to reside in different spatial orbitals. By staying out of each others way, the electrons lower their total energy.

“This gives us great insight into the valence state and electron coupling mechanisms of 5f electrons in plutonium and americium, two metals that are significant to nuclear reactors,” Moore said. “Our data will help us refine our theoretically predictive codes for these metals to give us a better understanding of the physical properties of the metals and how they will behave under extreme conditions.”

The Livermore research also helps fill a gap in a recent Nature paper (446, page 513, 2007) from Rutgers University that had a missing data point in a table. The LLNL americium and curium data fill the blank space in the table.

“The two papers (PRL and Nature) greatly further our understanding of the middle actinide metals – plutonium, americium and curium.”


Story Source:

The above story is based on materials provided by DOE/Lawrence Livermore National Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

DOE/Lawrence Livermore National Laboratory. "A New Understanding Of Crystal Structure Of Actinide Metals." ScienceDaily. ScienceDaily, 7 June 2007. <www.sciencedaily.com/releases/2007/06/070606113438.htm>.
DOE/Lawrence Livermore National Laboratory. (2007, June 7). A New Understanding Of Crystal Structure Of Actinide Metals. ScienceDaily. Retrieved April 20, 2014 from www.sciencedaily.com/releases/2007/06/070606113438.htm
DOE/Lawrence Livermore National Laboratory. "A New Understanding Of Crystal Structure Of Actinide Metals." ScienceDaily. www.sciencedaily.com/releases/2007/06/070606113438.htm (accessed April 20, 2014).

Share This



More Matter & Energy News

Sunday, April 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Small Reactors Could Be Future of Nuclear Energy

Small Reactors Could Be Future of Nuclear Energy

AP (Apr. 17, 2014) — After the Fukushima nuclear disaster, the industry fell under intense scrutiny. Now, small underground nuclear power plants are being considered as the possible future of the nuclear energy. (April 17) Video provided by AP
Powered by NewsLook.com
Horseless Carriage Introduced at NY Auto Show

Horseless Carriage Introduced at NY Auto Show

AP (Apr. 17, 2014) — An electric car that proponents hope will replace horse-drawn carriages in New York City has also been revealed at the auto show. (Apr. 17) Video provided by AP
Powered by NewsLook.com
Honda's New ASIMO Robot, More Human-Like Than Ever

Honda's New ASIMO Robot, More Human-Like Than Ever

AFP (Apr. 17, 2014) — It walks and runs, even up and down stairs. It can open a bottle and serve a drink, and politely tries to shake hands with a stranger. Meet the latest ASIMO, Honda's humanoid robot. Duration: 00:54 Video provided by AFP
Powered by NewsLook.com
German Researchers Crack Samsung's Fingerprint Scanner

German Researchers Crack Samsung's Fingerprint Scanner

Newsy (Apr. 16, 2014) — German researchers have used a fake fingerprint made from glue to bypass the fingerprint security system on Samsung's new Galaxy S5 smartphone. Video provided by Newsy
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:
from the past week

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