World's smallest diamonds used to make wires 3 atoms wide

BOSTON: Scientists have used the smallest possible bits of diamonds to assemble electrical wires just three atoms wide, an advance that could pave the way for fabrics that generate electricity.

By grabbing various types of atoms and putting them together LEGO-style, the new technique could potentially be used to build tiny wires for a wide range of applications, including optoelectronic devices that employ both electricity and light and superconducting materials that conduct electricity without any loss.

"What we have shown here is that we can make tiny, conductive wires of the smallest possible size that essentially assemble themselves," said Hao Yan, postdoctoral researcher at Stanford University in the US.

"The process is a simple, one-pot synthesis. You dump the ingredients together and you can get results in half an hour. It's almost as if the diamondoids know where they want to go," said Yan.

This animation shows molecular building blocks joining the tip of a growing nanowire.

Each block consists of a diamondoid - the smallest bit of diamond - attached to sulphur and copper atoms.

Like LEGO blocks, they only fit together in certain ways that are determined by their size and shape.

The copper and sulphur atoms form a conductive wire in the middle, and the diamondoids form an insulating outer shell.

Although there are other ways to get materials to self-assemble, this is the first one shown to make a nanowire with a solid, crystalline core that has good electronic properties, said Nicholas Melosh, from the US Department of Energy's SLAC National Accelerator Laboratory.

The needle-like wires have a semiconducting core - a combination of copper and sulphur known as a chalcogenide - surrounded by the attached diamondoids, which form an insulating shell.

Their size is important because a material that exists in just one or two dimensions - as atomic-scale dots, wires or sheets - can have very different, extraordinary properties compared to the same material made in bulk, Melosh said.

The new method allows researchers to assemble those materials with atom-by-atom precision and control.

The diamondoids they used as assembly tools are tiny, interlocking cages of carbon and hydrogen.

Found naturally in petroleum fluids, they are extracted and separated by size and geometry in a SLAC laboratory.