Posted by Mike Williams-RiceonJuly 28, 2014
Applying just the right amount of tension to a chain of carbon atoms can turn it from a metallic conductor to an insulator, report researchers.
Stretching the material known as carbyne—a hard-to-make, one-dimensional chain of carbon atoms—by just 3 percent can begin to change its properties in ways that engineers might find useful for mechanically activated nanoscale electronics and optics.
Until recently, carbyne has existed mostly in theory, though experimentalists have made some headway in creating small samples of the finicky material. The carbon chain would theoretically be the strongest material ever, if only someone could make it reliably.
The first-principle calculations by Rice University theoretical physicist Boris Yakobson and his coauthors, postdoctoral researcher Vasilii Artyukhov and graduate student Mingjie Liu, show that stretching carbon chains activates the transition from conductor to insulator by widening the material’s band gap.
Band gaps, which free electrons must overcome to complete a circuit, give materials the semiconducting properties that make modern electronics possible.