Amorphous diamond: a high-pressure superhard carbon allotrope

Compressing glassy carbon above 40 GPa, we have observed a new carbon allotrope with a fully sp(3)-bonded amorphous structure and diamondlike strength. Synchrotron x-ray Raman spectroscopy revealed a continuous pressure-induced sp(2)-to-sp(3) bonding change, while x-ray diffraction confirmed the per...

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Published inPhysical review letters Vol. 107; no. 17; p. 175504
Main Authors Lin, Yu, Zhang, Li, Mao, Ho-kwang, Chow, Paul, Xiao, Yuming, Baldini, Maria, Shu, Jinfu, Mao, Wendy L
Format Journal Article
LanguageEnglish
Published United States 19.10.2011
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Summary:Compressing glassy carbon above 40 GPa, we have observed a new carbon allotrope with a fully sp(3)-bonded amorphous structure and diamondlike strength. Synchrotron x-ray Raman spectroscopy revealed a continuous pressure-induced sp(2)-to-sp(3) 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.
ISSN:1079-7114
DOI:10.1103/physrevlett.107.175504