Chinese scientists have synthesized the world's first "super diamond."

Researchers from the Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences (hereinafter referred to as Xi'an Institute of Optics and Precision Mechanics) and the Center for High Pressure Science Research in Beijing have, for the first time internationally, artificially synthesized bulk samples of hexagonal diamond with a size of hundreds of micrometers to millimeters, with ordered structure and high purity. Combined with various characterization techniques, they comprehensively proved the successful synthesis of pure-phase hexagonal diamond samples from different angles. Recently, this research result was published in "Nature." This achievement has finally ended the long-standing controversy about the macroscopic existence of hexagonal diamond, making this strange material, which could only be occasionally found in cosmic meteorites, now reproducible in the laboratory.

Hexagonal diamond has attracted widespread attention due to its potential superior strength, thermal and optical properties compared to cubic diamond. However, all previous "discoveries" of hexagonal diamond were limited to extremely small sizes, mixed phases, or structurally unclear samples, and it has always been impossible to confirm its existence as a truly independent material.

After nearly 10 years of continuous breakthroughs, the research team used single-crystal graphite as a precursor, and successfully synthesized hexagonal diamond triple twinning samples of hundreds of micrometers in size with highly ordered structures under quasi-hydrostatic high pressure (2 GPa) and high temperature (1400 degrees Celsius) conditions within a diamond anvil cell.

After the synthesis of the samples, Professor Luo Duan's team at the Xi'an Institute of Optics and Precision Mechanics relied on ultra-high spatiotemporal resolution characterization techniques, and conducted in-depth analysis of the samples using atomic-resolution transmission electron microscopy and electron energy loss spectroscopy measurements. They found that the Vickers hardness of the samples reached as high as 110 GPa, with performance comparable to natural cubic diamond, confirming it as an independent and uniform "super diamond."

"Currently, the samples we have prepared meet the requirements of the industrial manufacturing field, and belong to super cutting and wear-resistant materials. They can be used to make 'diamond drills' and handle more 'delicate porcelain works,' " said Luo Duan. (Intern reporter Li Yuan)