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Updated: Mar 6, 2026

High Pressure Single Crystal Diffraction at PX^2
Published on: January 16, 2017
Bulk hexagonal diamond
Shoulong Lai1, Xigui Yang2, Jiuyang Shi3
1Henan Key Laboratory of Diamond Materials and Devices, Key Laboratory of Integrated Circuit, Ministry of Education, School of Physics, Zhengzhou University, Zhengzhou, China.
Researchers synthesized hexagonal diamond (HD), a rare carbon polymorph, from graphite. This breakthrough confirms HD
Area of Science:
- Materials Science
- Solid State Physics
- Crystallography
Background:
- Cubic diamond (CD) is a well-established material with significant industrial applications.
- Hexagonal diamond (HD), a polymorph of CD, has been theorized but lacked experimental evidence.
- The properties and existence of HD have been subjects of scientific debate.
Purpose of the Study:
- To synthesize phase-pure hexagonal diamond (HD).
- To experimentally confirm the existence and characterize the properties of HD.
- To elucidate the transformation pathway from graphite to HD.
Main Methods:
- Synthesis of HD from highly oriented pyrolytic graphite (HOPG) under specific temperature and pressure conditions.
- Advanced structural characterizations (e.g., X-ray diffraction, electron microscopy).
- Theoretical simulations to understand the graphite-to-diamond phase transition.
Main Results:
- Successful synthesis of millimetre-sized, phase-pure HD.
- Confirmation of HD's unique crystal structure and identity.
- HD exhibits superior hardness compared to CD and high thermal stability.
- Clarification of the transformation mechanism from HOPG to HD.
Conclusions:
- The existence of hexagonal diamond (HD) as a discrete carbon phase is experimentally confirmed.
- HD possesses unique properties, including enhanced hardness and thermal stability.
- This research opens avenues for HD's application in advanced technologies and resolves a long-standing scientific controversy.
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