Sunday, March 18, 2012

Scientists build graphene from scratch, heralds new age of designer materials


http://www.extremetech.com/extreme/122693-scientists-create-graphene-from-scratch-heralds-new-age-of-designer-materials
You’ve heard of “designer babies,” the idea that you can customize a baby by altering its DNA, but now a team of researchers from Stanford University and the Department of Energy have meddled around with the very fabric of reality and created the very first “designer electrons.”
As you probably know, the bulk of the universe is made up from just a few dozen elements, and each of these elements is made up of just a few subatomic particles: electrons, protons, neutrons, quarks, and so on. For the most part, the properties of every material — its flexibility, strength, conductivity — is governed by the bonds between its constituent atoms, which in turn dictate a molecule’s arrangement of electrons. This is most obvious in elements like carbon, where a single element can form materials as different as charcoal, graphene, and diamond, all by virtue of different electron arrangements.
In short, if you can manually move electrons around, you can create different or entirely new materials. That’s exactly what Stanford University has done: Using a scanning tunneling microscope (the blue point in the image above), the team of researchers placed individual carbon monoxide molecules on a clean sheet of copper to create “molecular graphene” — an entirely new substance (pictured right) that definitely isn’t graphene, but with electrons that act a lot like graphene. The team, which was led by Hari Manoharan, then proceeded to move these individual atoms around, changing the structure and electron arrangement of the material.
Molecular graphene“One of the wildest things we did was to make the electrons think they are in a huge magnetic field when, in fact, no real field had been applied,” Manoharan said. The team simulated where the atoms would be if there was a magnetic field, and then proceeded to move the individual atoms into these positions. Weirdly enough, the molecular graphene then behaved as if it was in a magnetic field. In other words, the presence of a magnetic field is neither here nor there: What really matters is the position of atoms and their effect on the arrangement of electrons.
What Stanford’s discovery means is that we could soon be looking at all sorts of new, designer materials. To reiterate, the physical properties of almost every substance is dictated by the position of atoms and the arrangement of electrons. The only reason that semiconductors exist — the only reason that the world is littered with computers, that I can write this story, and that you can read it — is because of the electron structure of atoms like silicon and germanium. The reason the table in front of you is a table is because of the way carbon atoms bond together.
Stanford University now has the power to create new materials and to tweak the properties of existing ones. It might turn out that silicon, by moving an atom slightly, can suddenly operate at higher speeds and leak less power — or maybe that copper wire can be made more conductive by slightly altering its electronic makeup. Really, though, it’s impossible to imagine the materials that scientists will end up making. For all I know, someone might create a version of oxygen that’s polka dotted, or iron that explodes under pressure. Exciting times!

Read more at Stanford

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