Subscribe free to our newsletters via your
  Space Industry and Business News  




Subscribe free to our newsletters via your




















Argonne Scientists Use Unique Diamond Anvils To View Oxide Glass Structures Under Pressure

-
by Staff Writers
Argonne IL (SPX) Nov 12, 2007
Researchers at the U.S. Department of Energy's Argonne National Laboratory have used a uniquely-constructed perforated diamond cell to investigate oxide glass structures at high pressures in unprecedented detail. Argonne physicist Chris Benmore and postdoctoral appointee Qiang Mei, along with colleagues at the University of Arizona, used microscopic laser-perforated diamond anvil cells to generate pressures of up to 32 gigapascals (GPa) - roughly one-tenth the pressure at the center of the Earth.

By "squashing" vitreous (glassy) arsenic oxide samples between the anvils, the researchers were able to determine the mechanism behind the structure's atypical behavior under high-pressure.

This research may have far-reaching affects in the geophysical sciences, Benmore said, because oxide glasses and liquids represent a significant percentage of the materials that make up the Earth. For example, knowing the atomic structure of oxide materials at high pressures may give scientists a window on the behaviors of magma during the formation of the early Earth and moon. "We now have a technique where we can look a lot of different silicate glasses that are relevant to the Earth's process and at the complex behaviors of the melts that formed the Earth's mantle," he said.

During their investigation, Benmore and Mei noticed that if arsenic oxide was subjected to high pressures the material underwent an unusual transformation at about 20 GPa, as the color of the compound changed from transparent to red. However, they did not know the atomic cause for this behavior.

By performing x-ray pair distribution function experiments at Argonne's Advanced Photon Source (APS), however, Benmore and Mei were able to see the atomic reconfiguration that produced the color change. Arsenic oxide, at normal pressures, typically exists in isolated molecular "cages" in which four arsenic atoms are surrounded by three oxygen atoms apiece - each of the six oxygen atoms is bounded to two arsenic atoms. When the pressure rose above 20 GPa, however, many of these molecular cages collapsed, creating new isomers in which each arsenic atom was bonded to six oxygen atoms.

Regular diamond anvils could not be used because they caused a great deal of background scattering that obscured the signal from the material. Previous experiments on vitreous materials had used mechanically drilled diamond anvil cells to create the high pressures, but these routinely failed at pressures above 15 GPa. This experiment involved one of the first-ever uses of laser-perforated diamond anvils combined with micro-focused high energy x-ray diffraction techniques, which have the ability to generate high pressures without also producing background noise.

Benmore hopes to extend his research to liquid oxides and silicates by heating them pass their melting points. By doing so, he expects to gain a better understanding of the structural transition, which is expected to occur more abruptly and be reversible in the liquid phases of these materials.

Related Links
DOE/Argonne National Laboratory
Advanced Photon Source
Space Technology News - Applications and Research



Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News


MIT Gel Changes Color On Demand
Cambridge MA (SPX) Oct 23, 2007
MIT researchers have created a new structured gel that can rapidly change color in response to a variety of stimuli, including temperature, pressure, salt concentration and humidity. Among other applications, the structured gel could be used as a fast and inexpensive chemical sensor, says Edwin Thomas, MIT's Morris Cohen Professor of Materials Science and Engineering. One place where such an environmental sensor could be useful is a food processing plant, where the sensor could indicate whether food that must remain dry has been overly exposed to humidity.







  • Electricity Grid Could Become A Type Of Internet
  • Google revs up profits as advertising revenues soar
  • Internet preparing to go into outer space
  • US cities' Wi-Fi dreams fading fast

  • United Launch Alliance Successfully Completes First Operational Delta IV Heavy Launch
  • Arianespace's 5th Ariane 5 Mission Is Cleared For November 9 Liftoff
  • ESA To Provide Essential Launch Control Services To EUMETSAT
  • Skynet 5B Satellite Ready For Launch On 9th November

  • Time Magazine Recognizes The X-48B
  • Virgin to offer carbon offsets alongside drinks and perfume
  • NASA sorry over air safety uproar
  • Airbus superjumbo makes first commercial flight

  • Northrop Grumman-Built Defense Support Program Flight 23 Satellite Successfully Launched
  • XTAR Awarded GSA Schedule Contract For Information Technology Services
  • DataPath Awarded 3 Million Dollars To Enhance US Marine's Satellite Transportable Terminals
  • Space Command Striving For Improved Field Communications

  • Argonne Scientists Use Unique Diamond Anvils To View Oxide Glass Structures Under Pressure
  • YES2 Team Claims A Space Tether World Record
  • NASA Unveils New Antenna Network
  • Northrop Grumman Awarded Patent For Innovative Payload Positioning System

  • Boeing Names Darryl Davis To Lead Advanced Systems For Integrated Defense Systems
  • Northrop Grumman Names John Landon VP Of Missiles, Technology And Space Programs
  • Dr Mary Cleave Appointed To Board Of Directors Of Sigma Space
  • Northrop Grumman Appoints GPS And Military Space VPs

  • SPOT - The World's First Satellite Messenger Now Shipping
  • Fujifilm Unveils GPS-Based Data Tape Tracker
  • Vacation Photos Create 3D Models Of World Landmarks
  • NASA Data May Help Improve Estimates Of A Hurricane's Punch

  • V7 Launches New Portable Navigation Devices
  • GPS Chipset Shipments To Grow From 110 Million To 725 Million Units In 2011
  • Providence Health And Services Chooses WWT and AeroScout For Wireless Asset Tracking Solution
  • Personal Navigation Devices Will Surpass 100 Million Units By 2011

  • 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