This 1D Graphene Switches From Conductor To Insulator When It Stretches

This 1D Graphene Switches From Conductor To Insulator When It Stretches
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You’ve heard all about the wonder properties of graphene, so come meet its one dimensional cousin, carbyne. A chain of single carbon atoms to graphene’s two-dimensional layer of atoms, carbyne has some pretty amazing properties of its own. By one measure, it’s the strongest material in the world (over graphene!), and a new study finds it has the strange ability to go from conductor to insulator with a small stretch.

Carbyne’s special properties means it could be used in nanoscale electronics that are activated by a tiny tugs or pushes. After all, one function of transistors — the building blocks of modern electrons — is essentially to switch between conducting and insulating.

But before we get too ahead of ourselves, it is important to note that carbyne is very difficult to make. (Graphene, on the other hand, is something you can make with Scotch tape.) Carbyne is sometimes found in compressed graphite, but scientists have only been able to synthesize it in chains 44 atoms long so far. The new study of carbyne’s properties is based on computer models rather than physical chains — nevertheless, the results are cool enough to be worth pondering.

The team at Rice University found that stretching carbyne by just 3 per cent switched it from conductor to insulator. The reason lies in quantum effects, so this is going to get a little weird. If you were to draw out carbyne’s molecular structure like in chemistry class, you’d alternate single and triple bonds (1-3). But in (quantum) reality, it kind of exists as both 1-3 and double bonds (2-2). When carbyne is stretched, however, it tips the balance toward 1-3, altering the behaviour of electrons so the material becomes an insulator.

This is all pretty theoretical at the moment, but it points toward why making and experimenting with carbyne could be pretty exciting. Graphene, you aren’t the only carbon wondermaterial on the block. [IEEE Spectrum, Nano Letters]

Picture: Vasilii Artyukhov/Rice University