Carbon as hard as rock but also elastic

A team of scientists from Yanshan University and Carnegie Institution for Science has developed a form of ultrastrong, lightweight carbon that is also elastic and electrically conductive. This unique combination of properties could serve a variety of applications from aerospace engineering to military armour.

The configuration of its electrons allows for numerous self-bonding combinations that give rise to a range of materials with varying properties. For example, transparent, superhard diamonds, and opaque graphite, which is used for both pencils and industrial lubricant, are comprised solely of carbon.

The scientists pressurised and heated a structurally disordered form of carbon, called glassy carbon, to about 250,000 times normal atmospheric pressure and heated to approximately 980°C to create the new strong and elastic carbon.

The team had previously tried subjecting glassy carbon to high pressures at both room temperature and extremely high temperatures. But the so-called cold-synthesised material could not maintain its structure when brought back to ambient pressure, and under the extremely hot conditions, nanocrystalline diamonds were formed.

The newly created carbon is comprised of both graphite-like and diamond-like bonding motifs, which allows the unique combination of properties. Under the high-pressure synthesis conditions, disordered layers within the glassy carbon buckle, merge, and connect in various ways. This process creates an overall structure that lacks a long-range spatial order, but has a short-range spatial organisation on the nanometer scale.

“Light materials with high strength and robust elasticity like this are desirable for applications where weight savings are of the utmost importance, even more than material cost,” explained Yanshan University professor Zhisheng Zhao. “What's more, we believe that this synthesis method could be honed to create other extraordinary forms of carbon and entirely different classes of materials.”