Edinburgh Uni led team unveil “ultimate” engineering material

The group - which includes scientist from the University of Bayreuth, Germany and Sweden’s University of Linköping - found that when carbon and nitrogen precursors were subjected to extreme heat and pressure, the resulting materials – known as carbon nitrides – were tougher than cubic boron nitride, the second hardest material after diamond.

It's claimed that the breakthrough opens doors for multifunctional materials to be used for industrial purposes including protective coatings for cars and spaceships, high-endurance cutting tools, solar panels and photodetectors.

Dr Dominique Laniel, University of Edinburgh

Materials researchers have attempted to unlock the potential of carbon nitrides since the 1980s, when scientists first noticed their exceptional properties, including high resistance to heat. Yet after more than three decades of research and multiple attempts to synthesize them, no credible results were reported.

To achieve this fresh breakthrough, the team subjected various forms of carbon nitrogen precursors to pressures of between 70 and 135 gigapascals – around one million times our atmospheric pressure – while heating it to temperatures of more than one and a half thousand degrees celsius. 

To identify the atomic arrangement of the compounds under these conditions, the samples were illuminated by an intense X-ray beam at three particle accelerators – the European Synchrotron Research Facility in France, the Deutsches Elektronen-Synchrotron in Germany and the Advanced Photon Source based in the United States. Researchers discovered that three carbon nitride compounds were found to have the necessary building blocks for super-hardness.

Remarkably, all three compounds retained their diamond-like qualities when they returned to ambient pressure and temperature conditions.

Further calculations and experiments suggest the new materials contain additional properties including photoluminescence and high energy density, where a large amount of energy can be stored in a small amount of mass.

Dr Dominique Laniel, Future Leaders Fellow, at the University of Edinburgh’s Institute for Condensed Matter Physics and Complex Systems said: “Upon the discovery of the first of these new carbon nitride materials, we were incredulous to have produced materials researchers have been dreaming of for the last three decades.”

 The research, published in Advanced Materials, was funded by the UKRI FLF scheme and European research grants.