A study claims that scientists have solved a decades-long puzzle and discovered a nearly unbreakable substance that could rival diamond as the hardest material on the planet. When carbon and nitrogen precursors were subjected to extreme heat and pressure, the resulting materials, known as carbon nitrides, were found to be tougher than cubic boron nitride, the second hardest material after diamond.
According to experts, the breakthrough opens the door for multifunctional materials to be used in industrial applications such as protective coatings for cars and spaceships, high-endurance cutting tools, solar panels, and photodetectors.
Since the 1980s, when scientists first discovered their exceptional properties, such as high heat resistance, materials researchers have attempted to unlock the potential of carbon nitrides. Despite this, no credible results were reported after more than three decades of research and multiple attempts to synthesize it.
These materials are not only outstanding in their multi-functionality, but show that technologically relevant phases can be recovered from a synthesis pressure equivalent to the conditions found thousands of kilometers in the Earth’s interior.
Dr Florian Trybel
Now, an international team of scientists led by researchers from the University of Edinburgh’s Centre for Science in Extreme Conditions and experts from the Universities of Bayreuth, Germany, and Linköping, Sweden, has achieved a breakthrough.
The researchers subjected various forms of carbon nitrogen precursors to pressures ranging from 70 to 135 gigapascals (roughly one million times our atmospheric pressure) while heating them to temperatures of over 1500 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.
Three carbon nitride compounds were discovered to have the necessary building blocks for super-hardness by researchers. Surprisingly, when exposed to ambient pressure and temperature, all three compounds retained their diamond-like properties.
Additional calculations and experiments indicate that the new materials have additional properties such as photoluminescence and high energy density, which means that a large amount of energy can be stored in a small amount of mass.
The potential applications of these ultra-incompressible carbon nitrides, according to researchers, are vast, potentially positioning them as the ultimate engineering materials to rival diamonds. The study, which was published in Advanced Materials, was supported by the UKRI FLF scheme as well as European research grants.
Dr Dominique Laniel, Future Leaders Fellow, Institute for Condensed Matter Physics and Complex Systems, School of Physics and Astronomy, University of Edinburgh, 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. These materials provide strong incentive to bridge the gap between high pressure materials synthesis and industrial applications.”
“These materials are not only outstanding in their multi-functionality, but show that technologically relevant phases can be recovered from a synthesis pressure equivalent to the conditions found thousands of kilometers in the Earth’s interior,” said Dr Florian Trybel, Assistant Professor, Department of Physics, Chemistry, and Biology, University of Linköping. We are confident that this collaborative research will open up new avenues for the field.”
