The well-known diamond is one of the hardest substances in nature. Research has found that hexagonal diamonds found in meteorites have higher hardness than ordinary diamonds and higher value. However, the artificial synthesis of high-purity hexagonal diamonds has always been a global challenge. Chinese scientists have recently successfully synthesized hexagonal diamond at the micrometer level, which was published in the international journal Nature on the 30th. The carbon atoms of diamond are arranged in a tetrahedral grid, which is hard and wear-resistant, and is known as the "king of hardness". However, this structure also has a weakness: certain planes are prone to displacement and sliding when subjected to force, limiting their strength. So scientists turned their attention to another type of super diamond with more exquisite structure and superior properties - hexagonal diamond. The formation conditions of hexagonal diamond are extremely demanding, and the biggest difficulty in artificial synthesis is that the formation energy of hexagonal diamond is higher than that of ordinary diamond under high temperature and high pressure. Therefore, ordinary diamond is often the main product of high temperature and high pressure, and it is difficult to obtain hexagonal diamond. Chinese scientists have innovatively proposed a method for transforming graphite into hexagonal diamond. Under controllable conditions of high temperature, high pressure, and quasi-static water pressure, graphite single crystals are compressed and heated to obtain high-purity hexagonal diamond. The carbon atoms of ordinary diamond are connected by the same bond length. The hexagonal diamond we synthesized has two different bond lengths between carbon atoms, with a quarter of the 'carbon carbon' bonds being shorter and stronger, overcoming the weakness of easy slip on diamond dense packing surfaces and possessing superior hardness and toughness. ”The corresponding author of the paper, Yang Wenge, said. Yang Liuxiang, the first author of the paper and a researcher at Beijing High Voltage Science Research Center, introduced that the synthesis of high-purity hexagonal diamond is attributed to two key technologies: firstly, selecting high-purity and impurity free natural graphite single crystals, which helps to obtain higher purity, micrometer sized, and structurally ordered hexagonal diamond samples; The second is to use appropriate detection methods - the R&D personnel continuously apply pressure to the graphite crystal and observe the changes in the sample using high-pressure in-situ X-ray, avoiding the slip of the dense packing surface, and ultimately producing pure and undeformed hexagonal diamond blocks. This work lays the methodological foundation for the next step of research on diamond-like materials. The superior hardness, thermal conductivity, optical properties, and quantum properties of hexagonal diamond will also open up new paths for the research and development of superhard materials and high-end electronic devices. ”High voltage physicist and foreign academician of the Chinese Academy of Sciences, Mao Heguang, said. (New Society)