by Staff Writers
Stockholm, Sweden (SPX) Jan 16, 2012
Physicists at Linkoping University have shown that a dose of hydrogen or helium can render the "super material" graphene even more useful.
Graphene has engendered high expectations whereof its extreme properties depend on the fact that it consists of a single sheet of carbon atoms. However the attraction forces between the atoms cause the sheets to be drawn to each other. One solution is to add atomic hydrogen between the layers.
Presented in the eminent journal Physical Review A, the researchers' calculations show that the hydrogen at a given concentration affects the atomic van der Waals forces and becomes repulsive instead of attractive. The result is that graphene sheets repel each other and float freely just a few nanometres apart (an example of the so-called quantum levitation).
Professor Bo E. Sernelius, who conducted the study in conjunction with his former doctoral student Mathias Bostrom, identifies several possible applications of the discovery:
+ Storage of hydrogen as vehicle fuel
+ Creation of a single graphene sheet by peeling them from a pile that has grown on a substrate of silicon carbide; a method developed at Linkoping University
+ Repulsive forces are ideal for the manufacture of friction-free components on a Nano scale, for example, robots and sensors for medical purposes.
In the present study the researchers began with two undoped sheets of graphene on a substrate of silicon dioxide (silica). The starting position is the van der Waals attractive forces and the sheets are compelled closer together. However once atomic hydrogen is added, repulsive forces arise. A similar effect was observed using other gases such as molecular hydrogen (H2) and helium.
Graphene is a two-dimensional material, which means that it retains a very special character. It is flexible, transparent, stronger than a diamond and has a superior ability to conduct electric current. In 2010 Andre Geim and Konstantin Novoselov received a Nobel Prize in Physics because for the first time ever they succeeded in producing stable flakes of material.
Repulsive van der Waals forces due to hydrogen exposure on bilayer graphene by Mathias Bostrom and Bo E. Sernelius. Physical Review A 85:1, 11 January 2012.
Nano Technology News From SpaceMart.com
Computer Chip Architecture, Technology and Manufacture
Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.
Graphene quantum dots: The next big small thing
Houston TX (SPX) Jan 16, 2012
A Rice University laboratory has found a way to turn common carbon fiber into graphene quantum dots, tiny specks of matter with properties expected to prove useful in electronic, optical and biomedical applications. The Rice lab of materials scientist Pulickel Ajayan, in collaboration with colleagues in China, India, Japan and the Texas Medical Center, discovered a one-step chemical proces ... read more
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. 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 Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|