Amorphous diamond: A high-pressure superhard carbon allotrope

Journal Article · Fri Dec 31 23:00:00 EST 2010 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.107.175504· OSTI ID:1065690

Lin, Yu ^[1]; Zhang, Li ^[2]; Mao, Ho Kwang ^[2]; Chow, Paul ^[3]; Xiao, Yuming ^[3]; Baldini, Maria ^[4]; Shu, Jinfu ^[2]; Mao, Wendy L. ^[5]

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1. Stanford Univ., Stanford, CA (United States)
2. Geophysical Lab., Carnegie Inst. of Washington, Washington, DC (United States)
3. High Pressure Collaborative Access Team (HPCAT), Geophysical Lab., Carnegie Inst. of Washington, Washington, DC (United States)
4. High Pressure Synergetic Consortium, Geophysical Lab., Carnegie Inst. of Washington, Washington, DC (United States)
5. SLAC National Accelerator Laboratory, Menlo Park, CA (United States)

Compressing glassy carbon above 40 GPa, we have observed a new carbon allotrope with a fully sp³-bonded amorphous structure and diamondlike strength. Synchrotron x-ray Raman spectroscopy revealed a continuous pressure-induced sp²-to-sp³ bonding change, while x-ray diffraction confirmed the perseverance of noncrystallinity. The transition was reversible upon releasing pressure. Used as an indenter, the glassy carbon ball demonstrated exceptional strength by reaching 130 GPa with a confining pressure of 60 GPa. Such an extremely large stress difference of >70 GPa has never been observed in any material besides diamond, indicating the high hardness of this high-pressure carbon allotrope.

• Research Organization: Energy Frontier Research Centers (EFRC); Energy Frontier Research in Extreme Environments (EFree)
• Sponsoring Organization: USDOE SC Office of Basic Energy Sciences (SC-22)
• DOE Contract Number: SC0001057
• OSTI ID: 1065690
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 17 Vol. 107; ISSN 0031-9007
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

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