Superhard Monoclinic Polymorph of Carbon

Quan Li, Yanming Ma, Artem R. Oganov, Hongbo Wang, Hui Wang, Ying Xu, Tian Cui, Ho-Kwang Mao, and Guangtian Zou
Phys. Rev. Lett. 102, 175506 – Published 29 April 2009

Abstract

We report a novel phase of carbon possessing a monoclinic C2/m structure (8atoms/cell) identified using an ab initio evolutionary structural search. This polymorph, which we call M-carbon, is related to the (2×1) reconstruction of the (111) surface of diamond and can also be viewed as a distorted (through sliding and buckling of the sheets) form of graphite. It is stable over cold-compressed graphite above 13.4 GPa. The simulated x-ray diffraction pattern and near K-edge spectroscopy are in satisfactory agreement with the experimental data [W. L. Mao et al., Science 302, 425 (2003)] on overcompressed graphite. The hardness and bulk modulus of this new carbon polymorph are calculated to be 83.1 and 431.2 GPa, respectively, which are comparable to those of diamond.

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  • Received 30 December 2008

DOI:https://doi.org/10.1103/PhysRevLett.102.175506

©2009 American Physical Society

Authors & Affiliations

Quan Li1, Yanming Ma1,*, Artem R. Oganov2,3,†, Hongbo Wang1, Hui Wang1, Ying Xu1, Tian Cui1, Ho-Kwang Mao4,‡, and Guangtian Zou1

  • 1State Key Lab of Superhard Materials, Jilin University, Changchun 130012, China
  • 2Department of Geosciences and New York Center for Computational Science, Stony Brook University, Stony Brook, New York 11794, USA
  • 3Department of Geology, Moscow State University, 119899 Moscow, Russia
  • 4Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, D.C. 20015-1305, USA

  • *Corresponding authors. mym@jlu.edu.cn
  • aoganov@notes.cc.sunysb.edu
  • h.mao@gl.ciw.edu

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Vol. 102, Iss. 17 — 1 May 2009

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