On the structure of a new superhard hexagonal carbon phase

B.-B. Zhang, Yongcheng Liang, Zaoyang Guo, Stéphane Bordas

    Research output: Chapter in Book/Conference paperConference paper

    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 Å, c 0=4.123Å) with a bulk modulus of 447 GPa and average density about 3.6g/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.

    Original languageEnglish
    Title of host publicationISCM II and EPMESC XII - Proc. of the 2nd Int. Symposium on Computational Mechanics and the 12th Int. Conf. on the Enhancement and Promotion of Computational Methods in Engineering and Science
    Pages489-493
    Number of pages5
    Volume1233
    EditionPART 1
    DOIs
    Publication statusPublished - 2010
    Event2nd International Symposium on Computational Mechanics, ISCM II, and the 12th International Conference on the Enhancement and Promotion of Computational Methods in Engineering and Science, EPMESC XII - Hong Kong, Macau, China
    Duration: 30 Nov 20093 Dec 2009

    Conference

    Conference2nd International Symposium on Computational Mechanics, ISCM II, and the 12th International Conference on the Enhancement and Promotion of Computational Methods in Engineering and Science, EPMESC XII
    CountryChina
    CityHong Kong, Macau
    Period30/11/093/12/09

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    Zhang, B-B., Liang, Y., Guo, Z., & Bordas, S. (2010). On the structure of a new superhard hexagonal carbon phase. In ISCM II and EPMESC XII - Proc. of the 2nd Int. Symposium on Computational Mechanics and the 12th Int. Conf. on the Enhancement and Promotion of Computational Methods in Engineering and Science (PART 1 ed., Vol. 1233, pp. 489-493) https://doi.org/10.1063/1.3452220