 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
Argonne Scientists Discover New Class Of Glassy Material
Argonne IL (SPX) Aug 05, 2008 Scientists at U.S. Department of Energy's Argonne National Laboratory are dealing with an entirely new type of frustration, but it's not stressing them out. Dynamic frustration has been found to be the cause of glassy behavior in materials that previously had none of the features of a normal glass. "This has been a puzzle for 10 years now," Argonne physicist Raymond Osborn said. Conventional wisdom states that glassy materials, such as common window glass, result when frustration prevents the atoms from forming a well-ordered crystal structure, and the material freezes into a disordered state like a frozen liquid. In spin glasses, it is the magnetic moments on each atom, rather than the atoms themselves, that freeze into a disordered state at low temperatures, so that they point in random directions. However, there has to be some disorder in the atomic structure and some frustration in the magnetic interactions which prevents the magnetic moments from ordering so that they can freeze into spin glasses. Scientists have struggled for more than a decade to understand why PrAu2Si2 is a spin glass. There is no sign of atomic disorder in the compound and, no reason for the magnetic interactions to be frustrated. Using the results of neutron scattering experiments, Osborn and his collaborators concluded the frustration results from temporal or dynamic frustration rather static frustration. Although PrAu2Si2 seems to have an ordered structure, by delving deeper, Osborn found that the magnetic moments are continually fluctuating in magnitude causing the equivalent of temporal potholes that appear and then disappear long enough to disrupt the magnetic alignment. These fluctuations occur because the magnetic moments in this material are unstable and can be destroyed temporarily by electrons scattering off the atoms. "The discovery of dynamic frustration reveals a whole new class of glassy materials whose behavior is governed by dynamic rather than static disorder," Osborn said. This discovery may allow scientists to tune the degree of frustration and therefore develop a better understanding of how glasses are formed in nature. Related Links DOE/Argonne National Laboratory Space Technology News - Applications and Research
Scientist says feathers are future of Asia construction
Manila (AFP) Aug 3, 2008A Filipino scientist says he has created a new composite building board made of chicken feathers that could be a major breakthrough for the construction industry in Asia. |
|
|
| The content herein, unless otherwise known to be public domain, are Copyright Space.TV Corporation. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space.TV Corp on any Web page published or hosted by Space.TV Corp. Privacy Statement |
