Discover a new path! Chinese scientists synthesize hexagonal diamond for the first time
2025-02-19 10:09:27
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“The team of Liu Bingbing and Yao Mingguang from the High Pressure Laboratory of Jilin University, in collaboration with Professor Zhu Shengcai of CUHK, published a study in Nature Materials, discovering a new path for graphite to be converted into hexagonal diamond under high temperature and high pressure, and synthesizing high-quality samples for the first time, with a hardness exceeding that of cubic diamond and good thermal stability. This achievement provides a new way to synthesize hexagona”
The team of Liu Bingbing and Yao Mingguang from the High Pressure Laboratory of Jilin University, in collaboration with Professor Zhu Shengcai of CUHK, published a study in Nature Materials, discovering a new path for graphite to be converted into hexagonal diamond under high temperature and high pressure, and synthesizing high-quality samples for the first time, with a hardness exceeding that of cubic diamond and good thermal stability. This achievement provides a new way to synthesize hexagonal diamond, confirms its independent existence, enriches the field of superhard carbon materials, or expands the application of cubic diamond, and is also of great significance to meteorite diamond and geological research.
In 1967, American scientists discovered rare 'super diamonds' in a meteorite crater. They have a hexagonal crystal structure and are harder, but the artificial synthesis of pure hexagonal diamonds has long been unsolved. Previous studies have suggested that the sp3 carbon high-pressure phase structure is the key to the transformation of graphite to cubic diamond. Inspired by this, the team designed a high-temperature and high-pressure experiment, using laser-heated diamond anvil cell technology to find that graphite forms a post-graphite phase under high pressure, and then successfully synthesized hexagonal diamond through local heating. The research team has been studying carbon materials under ultra-high pressure for a long time and discovered a variety of new structures and properties (published in Nature, Science). Previous studies proposed a new mechanism for the transformation of graphite to cubic diamond, pointing out that the sp3 carbon high-pressure phase structure is the key (published in Phys. Rev. Lett.). Inspired by this, the team designed a high-temperature and high-pressure experiment, using laser-heated diamond anvil cell technology to find that graphite forms a 'post-graphite phase' at 50GPa, and then successfully synthesized hexagonal diamond by heating. Combined with molecular dynamics simulation, it revealed the key role of graphite layer stacking in the formation of hexagonal diamond, confirming the new path. The research team has been independently developing large-cavity ultra-high pressure technology for a long time, solving the problem of the size and pressure limit of the press cavity, innovating tungsten carbide anvils and assemblies, achieving 40GPa ultra-high pressure, an increase of 60%, and supporting the preparation of high-temperature and high-pressure materials (Engineering, Chin. Phys. Lett. published). For the synthesis of hexagonal diamond, the thermal conductivity difference material is introduced to produce a temperature gradient, simulating high temperature and high pressure conditions, and millimeter-level high-oriented hexagonal diamond is obtained at 30GPa and 1400℃. The hardness of this diamond is 155±9GPa, which is 40% higher than that of natural diamond, and the vacuum thermal stability reaches 1100℃, which is better than nano diamond. This achievement provides an effective way to artificially synthesize pure-phase hexagonal diamond, adding new members with better performance to superhard materials and new carbon materials. It is also of great significance for in-depth understanding of the specific sources of diamonds in meteorites and major geological events.
Discover a new path! Chinese scientists synthesize hexagonal diamond for the first time
The team of Liu Bingbing and Yao Mingguang from the High Pressure Laboratory of Jilin University, in collaboration with Professor Zhu Shengcai of CUHK, published a study in Nature Materials, discovering a new path for graphite to be converted into hexagonal diamond under high temperature and high pressure, and synthesizing high-quality samples for the first time, with a hardness exceeding that of cubic diamond and good thermal stability. This achievement provides a new way to synthesize hexagona