Under Pressure, Vanadium Won't Turn Down The Volume

Though it is expensive to mine and refine, vanadium is extremely important in the industrial world, where its main use is as a steel additive. Steel that contains vanadium is exceptionally strong and resistant to metal fatigue, making it ideal for kitchen knives that stay sharp almost indefinitely, and jet turbine blades that can withstand high speed and abrasion.

by Staff Writers
Washington DC (SPX) Feb 23, 2007
Scientists at Carnegie's Geophysical Laboratory have discovered a new type of phase transition-a change from one form to another-in vanadium, a metal that is commonly added to steel to make it harder and more durable. Under extremely high pressures, pure vanadium crystals change their shape but do not take up less space as a result, unlike most other elements that undergo phase transitions. The work appears in the February 23 issue of Physical Review Letters.

Led by High Pressure Collaborative Access Team (HPCAT) research scientist Yang Ding, the team* used a diamond anvil cell to subject vanadium crystals to pressures more than 600 thousand times higher than the atmospheric pressure at sea level (which is about one bar). Using the high-resolution HPCAT x-ray facility, the scientists were able to detect that the basic atomic packing units of vanadium crystals had changed from a cube to a rhombohedron, which resembles a cube whose sides have been squashed from squares into diamond shapes.

"Trying to understand why high-pressure vanadium uniquely has the record-high superconducting temperature of all known elements inspired us to study high-pressure structure of vanadium," Ding said. "We had no idea that we would discover a completely new type of phase transition."

The most familiar phase transitions are those between gas, liquid, and solid forms. In general, increasing pressure and decreasing temperature will cause a substance to take up less space and eventually form a solid. But as a result of their atoms packing in closer together at extremely high pressures, some solids undergo further changes in their physical properties and can even change shape, which usually results in a change in volume. But in this respect, vanadium is unique.

Pure vanadium crystals in cubic form were thought to be able to resist pressures over several million bars. Recent theoretical calculations, however, suggested that pressure could cause unusual electronic interactions in vanadium that would destroy the cubic crystals. Instead, vanadium avoids this collapse by changing to a rhombohedron.

"Although this type of transition was first observed in vanadium, it suggests that we should reexamine many other elements we thought were very stable," Ding explained. "Moreover, the transition provides a new explanation for the continuous rising of superconducting temperature in high-pressure vanadium, and could lead us to the next breakthrough in superconducting materials."

*In addition to Ding, the team includes Ho-kwang Mao (GL and HPCAT), Jinfu Shu (GL), Paul Chow (HPCAT), and Rajeev Ahuja and Wei Luo (Uppsala University, Uppsala, Sweden).

TECH SPACE

Light Carbon-Fiber Structure Protects Heavy Space Cargo

Kirtland AFB NM (SPX) Feb 22, 2007
With a successful, inaugural performance during the launch of the TacSat2 micro satellite in December, an innovative, lightweight space cargo accommodation technology, comprised of carbon fibers and epoxy forming beams and an outer skin, delivered on the expectations of scientists serving with the Air Force Research Laboratory's Space Vehicles Directorate, Kirtland Air Force Base, N.M., who established the foundation for this project almost 13 years ago.

INTERNET SPACE World Getting Ready To Change The Light Bulb Hong Kong Internet Access Fully Restored New Damage And Bad Weather Delay Asian Internet Repairs Asia Turns To Time-Tested Solution For Damaged Internet Cables	LAUNCH PAD SERVIS-2 To Be Launched On Rockot Russia Space Agency Hopes Sea Launch Will Resume Operation In 2007 United Launch Alliance First East Coast Launch A Total Success ILS Proton To Launch Ciel-2 Satellite To Serve North America
AEROSPACE Can UABC Take Russian Aircraft-Makers Out Of Spin Superjet To Be Tested For Strength Anger As Britons Face Air Tax Hike Bats In Flight Reveal Unexpected Aerodynamics	MILITARY COMMUNICATIONS Harris And BAE Systems Demonstrate Highband Networking Radio Using Directive Beam Technology Australia To Host US MUOS Listening Post DRS Tech To Provide Satellite Bandwidth For Defense Information Network Raytheon To Deliver Navy Multiband Terminal Satellite Communication System For Testing
TECH SPACE Light Carbon-Fiber Structure Protects Heavy Space Cargo High-Quality Helium Crystals Show Supersolid Behavior Under Pressure, Vanadium Won't Turn Down The Volume Introducing The Coolest Spacecraft In The Universe	APPOINTMENTS Alan Stern Appointed To Lead Science Mission Directorate Former Space Agency Chief May Head RSC Energia Northrop Grumman Names Teri Marconi VP Of Combat Avionics For Electronic Systems Northrop Grumman Appoints Joseph Ensor Vice President Of Surveillance And Remote Sensing
EARTH OBSERVATION Scientists Gear Up For Envisat 2007 Symposium ITT Passes Critical Design Review for GOES-R Advanced Baseline Imager Sandstorm Over The Mediterranean 3D Upstart Eyes Google Earth With Helicopter	GPS NEWS GPS Upgrade Will Require Complicated Choreography China Puts New Navigation Satellite Into Orbit GMV Signs Galileo Contracts Worth Over 40 Million Euros Port Of Rotterdam To Use SAVI Networks Savitrak For Cargo Security And Management Service

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