On the Structure of a New Superhard Hexagonal Carbon Phase

Zhang, B., Liang, Y., Guo, Z. and Bordas, S. (2010) On the Structure of a New Superhard Hexagonal Carbon Phase. In: Lu, J.W.Z., Leung, A.Y.T., Iu, V.P. and Mok, K.M. (eds.) ISCM II and EPMESC XII, PTS 1 and 2. Series: AIP Conference Proceedings (1233). American Institute of Physics: Melville, NY, pp. 489-493. ISBN 978-0-7354-0778-7 (doi: 10.1063/1.3452220)

Abstract

Molecular dynamics simulations show that graphite will transform into a superhard phase under cold compression. Recent experiments show that there is a sp(3)-rich hexagonal carbon polymorph (a(0)=2.496 angstrom, c(0)=4.123 angstrom) with a bulk modulus of 447 GPa and average density about 3.6 g/cm(3), restricted to the space group of P-62c (No. 190), but the detailed atomic structure was not obtained [Wang et al, P. Natl. Acad. Sci. 101(38), 13699]. Here we set carbon atoms occupying P-62c 4f Wyckoff positions of P-62c, and calculate the total energy of the different structures changing the internal parameter z by first-principles calculations using geometry optimisation algorithm in CASTEP code, which shows that the stable structures in energy (at local minimum points) are hexagonal carbon (z =1/4) and hexagonal diamond (z = 1/16). The calculated mechanical properties and lattice parameters of the structure P-62c 4f(z = 1/4) are in good agreement with those of the new hexagonal carbon proposed by Wang et al, which indicates that the atomic structure is a possible candidate.

• Item Type: Book Sections
• Additional Information: 2nd International Symposium on Computational Mechanics Hong Kong, PEOPLES R CHINA, NOV 30-DEC 03, 2009 Series ISSN: 0094-243X
• Status: Published
• Glasgow Author(s) Enlighten ID: Bordas, Dr Stephane and Zhang, Dr Bin and Guo, Dr Zaoyang
• Authors: Zhang, B., Liang, Y., Guo, Z., and Bordas, S.
• College/School: College of Science and Engineering > School of Engineering > Infrastructure and Environment
• Publisher: American Institute of Physics
• ISBN: 978-0-7354-0778-7