Hexagonal diamond synthesized!
March12, 2025
Natural and synthetic diamonds typically possess a cubic lattice, while a rare hexagonal form, known as hexagonal diamond (HD), remains largely unexplored due to the limited purity and small size of most available samples. The synthesis of HD remains challenging, and its very existence continues to be debated.
Recently, researchers achieved the synthesis of well-crystallized, nearly pure HD by heating highly compressed graphite, a method applicable to both bulk and nanoscale graphitic precursors. Experimental and theoretical analyses reveal that the formation of a post-graphite phase within compressed graphite, along with temperature gradients, facilitates HD growth. This approach has enabled the production of a millimeter-sized, highly oriented HD block composed of stacked single-crystal-like HD nanolayers. The resulting HD demonstrates exceptional thermal stability up to 1,100 °C and an impressive hardness of 155 GPa. These findings provide valuable insights into the graphite-to-diamond transformation under high pressure and temperature, paving the way for the fabrication and potential applications of this remarkable material.
Diasemi---Diamond Semiconductor Researching Center
Silicon Valley, CA
