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5d ago

Lab-Made Hexagonal Diamond Clears Key Tests, Slightly Out-Hardens Cubic Diamond

New diffraction peaks with matched spectroscopic signatures persuade more researchers that a long-disputed carbon phase exists.

A series of hexagonal clear pieces, reflecting rainbow prisms
Image
The Canyon Diablo crater, better known as Barringer Crater, was created in Arizona by a meteor containing what may be the first example of hexagonal diamond.

Overview

  • Researchers in China report millimeter-scale, phase-pure hexagonal diamond produced from highly oriented pyrolytic graphite at about 20 gigapascals and 1,300–1,900 °C using tungsten‑carbide anvils.
  • X‑ray diffraction shows the additional peaks required to distinguish the phase from defective cubic diamond, with spectroscopic analyses and simulations reinforcing the identification.
  • The samples measured roughly 114 gigapascals in hardness with greater stiffness and markedly better oxidation resistance than common cubic diamond.
  • The Nature paper follows 2025 reports of similar material, and Ho‑kwang Mao says the new results reproduce his team’s findings as questions about trace cubic‑diamond contamination persist.
  • Potential uses include cutting and drilling tools, thermal management and quantum sensing, while scaling, purity improvements and further independent replication remain priorities.