Chinese scientists synthesized an artificial "super diamond" that is 40% harder and far more durable than natural diamonds. The findings of the research team were published in early February in the journal Nature Materials.
Led by Liu Bingbing and Yao Mingguang from Jilin University, the researchers discovered that by heating highly compressed graphite, it can transform into a hexagonal diamond. This synthetic creation possesses a hexagonal crystal form, which provides much greater strength compared to the cubic structure of most natural diamonds. The "super diamond" structure exhibits high thermal stability up to 1,100°C and a very high hardness of 155 Giga Pascals (GPa), according to the scientists.
"Our findings offer valuable insights regarding the graphite-to-diamond conversion under elevated pressure and temperature, providing opportunities for the fabrication and applications of this unique material," the scientists wrote in the study.
Until now, hexagonal diamonds could only be found in small, impure samples in meteorite impact areas, making them rare and often very small. Lonsdaleite, the first ultra-hard diamond, was discovered in 1967 in the Canyon Diablo meteorite in Arizona, and its applications are largely unexplored due to the low purity and small size of most obtained samples.
The synthesis of lonsdaleite in laboratories has remained unverified beyond a few studies, and since its discovery, replicating its structure has been challenging. However, the new method developed by Chinese scientists shows that these diamonds can be produced in larger and purer forms. Researchers noted that hexagonal diamonds could be a superior alternative to conventional diamonds in applications such as processing and drilling, with uses in machining drilling.
These properties could create wide applications in industry, particularly in aerospace engineering, military defense construction, and automotive sectors. Experts say the creation of the "super diamond" could lead to advances across several key industries that rely on materials with such properties. "There are significant challenges to overcome before this material can be used at scale, but if a method could be found to produce bulk quantities or coat other materials in it, then depending on price it might find industrial use," said Ben Green, Associate Professor at the University of Warwick’s Department of Physics, according to Metro.
"Despite the diamond's rare qualities, it would be no more expensive than natural diamonds sold at jewelry stores," said Professor Oliver Williams, Chair of the Condensed Matter and Photonics Group at Cardiff University. "A synthetic diamond could be as low as $300 from China," Williams stated, according to Metro. "If you make a 40% harder one, there has to be a premium, but I can’t imagine that it’ll be much higher."
While laboratory-grown diamonds are not new, the development of this super diamond provides a framework for understanding the transformation of graphite into diamond under high pressure and temperature. The researchers state that this study further opens opportunities for fabricating the material to suit applications.
In 2021, a study led by scientists at the Lawrence Livermore National Laboratory in the United States claimed to have created hexagonal diamonds, contributing to the understanding of ultra-hard or super diamonds. However, the new method developed by Chinese scientists shows that these diamonds can be produced in larger and purer forms.
Natural diamonds mostly have a cubic cage or lattice arrangement of their carbon atoms, while graphite is composed of flat layers. The super diamond synthesized by the Chinese researchers has a hexagonal crystal structure, which provides much greater strength. The structure of this hexagonal diamond is close to that of lonsdaleite.
The collisions that create impact craters generate extremely high heat and pressure, which can transform certain rocks into diamonds. Lonsdaleite, first discovered in the Canyon Diablo meteorite in Arizona, is composed of atoms bonded in a rigid three-dimensional structure, giving it extreme resistance.
This artificial super diamond not only exhibits hardness and thermal stability but also could be turned into engagement rings. Experts say that lonsdaleite diamonds could start a new era in the engagement ring and gemstone market because they are much more durable than traditional diamonds.
The article was written with the assistance of a news analysis system.