Indentations in diamond caused by the new superhard carbon.
Credit: Lin Wang, Carnegie Institution of Washington Indentations in diamond caused by the new superhard carbon.

Scientists' drive to experiment with the entire range of elements in the periodic table often leads to the difficult and expensive harvesting of rare substances. But one element that has received significant attention lately is one of the most common—carbon. The fourth most plentiful element in the universe assumes many manifestations, from nanotubes to fullerenes. Moreover, its versatile nature means that it can be both soft and powdery (graphite) or rock-hard (diamond).

A collaborative venture led by Washington, D.C.'s Carnegie Institution for Science has recently resulted in a novel form of carbon. Unlike the other typical allotropes, which are either crystalline or amorphous, the new carbon is a hybrid of the two states. The research team began with an organized structure known as carbon-60. By adding an organic solvent and applying pressure, the material's original pentagonal and hexagonal framework began to crumple. However, the original lattice framework remained intact.

The result is a material so hard it can make an indentation in diamond. “We created a new type of carbon material, one that is comparable to diamond in its inability to be compressed,” said Carnegie professor Lin Wang. “Once created under extreme pressures, this material can exist at normal conditions, meaning it could be used for a wide array of practical applications.”

“Hybridization of crystalline and amorphous structures at an atomic level hasn’t been experimentally observed, although scientists believed such structures could be created,” Wang added. “The finding in this paper should be the first of its kind.”

Researchers from Jilin University, the University of Nebraska, Argonne National Laboratory, Stanford University, and Carnegie collaborated on the effort.