Published on January 18th, 2014 | by Tina Casey1
Jumbo Shrimp, Meet 3-D Graphene
And the oxymoron of the day award goes to…sodium bismuthate, an innocuous little yellow inorganic compound that, according to researchers at Lawrence Berkeley National Laboratory, could possess all the superior conductive properties of its two-dimensional rival, graphene — and may even surpass it.
For those of you new to the topic, we’ve been calling graphene the nanomaterial of the new millennium and writing about it endlessly (here, here, here, and here at our sister site PlanetSave just for starters).
Graphene is of a sheet of carbon atoms only one atom thick, but combine its unique properties as a conductor with a strength estimated at 200 times that of steel, and you have the formula for a new generation of ultra efficient electronic, photovoltaic and energy storage devices, to name a few.
3-D “Graphene” from Lawrence Berkeley National Laboratory
The problem with graphene is that it is notoriously finicky and difficult to produce at commercial scale, so the search has been on for more cooperative substances.
The question is where to start looking, and the answer is to start with one of the key characteristics of graphene that make its conductive properties so powerful.
One of those characteristics is the presence of 2-D Dirac fermions (named after the physicist Paul Dirac), which are particles that don’t have an anti-particle.
In a first-of-its-kind discovery, the Berkeley team verified that 3-D Dirac fermions can exist within sodium bismuthate.
More specifically, as described by Berkeley Lab, “sodium bismuthate can exist as a form of quantum matter called a three-dimensional topological Dirac semi-metal (3DTDS).”
That can lead to all sorts of good things, according to research team leader Yulin Chen of Oxford University:
A 3DTDS is a natural three-dimensional counterpart to graphene with similar or even better electron mobility and velocity. Because of its 3D Dirac fermions in the bulk, a 3DTDS also features intriguing non-saturating linear magnetoresistance that can be orders of magnitude higher than the materials now used in hard drives, and it opens the door to more efficient optical sensors.
As for the next step, that actually might not directly involve sodium bismuthate. It is an unstable material that would require special packaging when used in devices, but the discovery of 3-D Dirac fermions in sodium bismuthate could help stimulate the discovery of similar properties in more stable materials.
Whatever material is involved, according to Chen a 3-D system would be even more efficient over a broader range of applications than graphene, while skipping around some of the fabrication issues besetting graphene.
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