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Prediction of a superhard carbon-rich C-N compound comparable to diamond
journal contribution
posted on 2015-01-01, 00:00 authored by J Hao, H Liu, Weiwei LeiWeiwei Lei, X Tang, J Lu, Dan LiuDan Liu, Y LiUntil now, it has been a challenge both in experiment and in theory to design new superhard materials with high hardness values that are comparable to that of diamond. Here, by using first-principles calculations, we have introduced two new phases for a carbon-rich C-N compound with stoichiometry C3N, which is predicted to be energetically stable or metastable with respect to graphite and solid N2 at ambient pressure. It is found that C3N has a layered structure containing graphitic layers sandwiched with freely rotated N2 molecules. The layer-structured C3N is calculated to transform into a three-dimensional C2221 structure at 9 GPa with sp3-hybridized C atoms and sp2-hybridized N atoms. Phonon dispersion and elastic constant calculations reveal the dynamical and mechanical stability of the C2221 phase of C3N at ambient pressure. Significantly, first-principles ideal strength calculations indicate that the C2221 phase of C3N is a superhard material with an estimated Vickers hardness (∼76 GPa) comparable to that of diamond (60-120 GPa). The present results shed strong light on designing new superhard materials in the C-N system.
History
Journal
Journal of physical chemistry cVolume
119Issue
51Pagination
28614 - 28619Publisher
American Chemical SocietyLocation
Washington, D.C.Publisher DOI
ISSN
1932-7447eISSN
1932-7455Language
engPublication classification
C Journal article; C1 Refereed article in a scholarly journalCopyright notice
2015, American Chemical SocietyUsage metrics
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