An international team of scientists – led by researchers from the Centre for Science at Extreme Conditions at the University of Edinburgh and experts from the University of Bayreuth, Germany, and the University of Linköping, Sweden have solved a decades-long puzzle and unveiled a nearly unbreakable substance that could rival diamond, as the hardest material on Earth.
The compounds known as carbon nitrides, created by subjecting carbon and nitrogen precursors to extremely high heat and pressure, were more resilient than cubic boron nitride, the second hardest material after diamond.
Scientists have been trying to harness the potential of carbon nitrides since the 1980s due to their exceptional properties, particularly their high heat resistance. Despite over three decades of research and numerous attempts to create them, only credible results were reported now.
Now, scientists have finally achieved a breakthrough. The research team exposed different carbon nitrogen precursors to extreme conditions, applying pressures ranging from 70 to 135 gigapascals (about one million times atmospheric pressure) and heating them to temperatures exceeding 1,500 degrees Celsius.
To determine the atomic structure of the compounds formed under these extreme conditions, the samples were illuminated by intense X-ray beams at three particle accelerators: the European Synchrotron Research Facility in France, the Deutsches Elektronen-Synchrotron in Germany, and the Advanced Photon Source in the United States.
The scientists identified three carbon nitride compounds with the essential components for super-hardness. Remarkably, all three compounds maintained their diamond-like characteristics when returning to regular pressure and temperature conditions.
Additional calculations and experiments indicated that these new materials possess extra properties, including photoluminescence and high energy density, meaning they can store significant energy in a small mass. The potential applications for these ultra-incompressible carbon nitrides are extensive, positioning them as possible ultimate engineering materials to rival diamonds.
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 strongly incentivize bridging the gap between high-pressure materials synthesis and industrial applications.”
Dr. Florian Trybel, Assistant Professor, Department of Physics, Chemistry and Biology, University of Linköping, said, “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. We strongly believe this collaborative research will open up new possibilities for the field.”
Journal Reference:
- Dominique Laniel, Florian Trybel et al. Synthesis of Ultra-Incompressible and Recoverable Carbon Nitrides Featuring CN4 Tetrahedra. Advanced Materials. DOI: 10.1002/adma.202308030