Scientists have achieved a groundbreaking feat by unraveling a longstanding puzzle, introducing a substance that could potentially rival diamond as the hardest material on Earth. Published in the journal Advanced Materials, the research centers around carbon nitrides, which emerge when carbon and nitrogen precursors undergo extreme heat and pressure. These materials were found to be tougher than cubic boron nitride, the second hardest substance after diamond. The implications of this breakthrough extend across various industries, opening doors for multifunctional materials with applications in protective coatings for cars and spaceships, high-endurance cutting tools, solar panels, and photodetectors.
The quest to unlock the potential of carbon nitrides dates back to the 1980s, marked by scientists recognizing their exceptional properties, particularly high resistance to heat. Despite over three decades of research and multiple attempts to synthesize them, credible results were elusive. However, an international team of scientists, led by researchers from the Center for Science at Extreme Conditions at the University of Edinburgh, along with experts from the University of Bayreuth, Germany, and the University of Linköping, Sweden, has finally achieved a breakthrough.
The researchers subjected various forms of carbon nitrogen precursors to extreme conditions, applying pressures ranging from 70 to 135 gigapascals—approximately 1 million times atmospheric pressure—while heating them to temperatures exceeding 1,500°C. To identify the atomic arrangement of the resulting compounds under these conditions, intense X-ray beams illuminated the samples 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 outcome revealed three carbon nitride compounds with the necessary building blocks for super-hardness, surpassing cubic boron nitride. Remarkably, these compounds retained their diamond-like qualities when returning to ambient pressure and temperature conditions. Further calculations and experiments indicated that these materials possess additional properties, including photoluminescence and high energy density—where a large amount of energy can be stored in a small mass.
The potential applications of these ultra-incompressible carbon nitrides are vast, positioning them as ultimate engineering materials that could rival diamonds. Dr. Dominique Laniel, expressing incredulity at the discovery, stated, “These materials provide strong incentive to bridge the gap between high-pressure materials synthesis and industrial applications.” Dr. Florian Trybel emphasized not only the outstanding multi-functionality of these materials but also their recovery from synthesis conditions resembling those found thousands of kilometers within the Earth’s interior. The collaborative research is anticipated to open up new possibilities in the field, showcasing the transformative potential of these super-hard materials.
Source: University of Edinburgh