The new graphene?

1 May 2012

New properties of graphene have been discovered at a remarkable rate since the world’s thinnest material was first characterised by Professors Andre Geim and Konstantin Novoselov in 2004. However, the one-atom-thick sheet of carbon could lose its status as the world’s go-to wonder-material as early studies into bismuth-antimony films have revealed similar and even additional properties.

The research by Massachusetts Institute of Technology (MIT), published in the journal Nano Letters, suggests that bismuth-antimony films possess similar electronic properties , including high-speed conduction, with added potential in controlling these characteristics by altering temperature and pressure, or the materials thickness or layer orientation.

Materials science and engineering PhD candidate Shuang Tang and MIT Professor Mildred Dresselhaus were initially unsure if bismuth could have the Dirac cone properties possessed by graphene that allow electrons to travel though a material, as Tang describes, ‘like a beam of light.’

Two-dimensional Dirac cones are named after the shape produced on a graph when the energy of electrons passing through a material is plotted against momentum. It was the work of a Ukrainian collaborator of MIT that suggested these properties might be possible in bismuth-antimony films and the discovery means they might have an application in computer-chips or thermoelectric generators and coolers.

It has been suggested that electron flow in the films could be hundreds of times faster than in conventional silicon chips, while their strong thermal-insulation properties could lead to incredibly efficient power production. Although these are all uses that have been identified for graphene, bismuth could provide something new by allowing its properties to be controlled according to varying conditions or even offering different functions in different layers of the same material.

While the initial research into the material is positive, Prof Dresselhaus has stressed that its applications remain speculative at present with further research needed to test and analyse samples to build on the knowledge obtained from theoretical modelling. Despite this bismuth-antimony films are certainly a promising new area of nanotechnology.

Further information

Nano Letters: Constructing Anisotropic Single-Dirac-Cones in Bismuth-Antimony Thin Films, Tang and Dresselhaus, 2012

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