These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Bonding changes in compressed superhard graphite.
    Author: Mao WL, Mao HK, Eng PJ, Trainor TP, Newville M, Kao CC, Heinz DL, Shu J, Meng Y, Hemley RJ.
    Journal: Science; 2003 Oct 17; 302(5644):425-7. PubMed ID: 14564003.
    Abstract:
    Compressed under ambient temperature, graphite undergoes a transition at approximately 17 gigapascals. The near K-edge spectroscopy of carbon using synchrotron x-ray inelastic scattering reveals that half of the pi-bonds between graphite layers convert to sigma-bonds, whereas the other half remain as pi-bonds in the high-pressure form. The x-ray diffraction pattern of the high-pressure form is consistent with a distorted graphite structure in which bridging carbon atoms between graphite layers pair and form sigma-bonds, whereas the nonbridging carbon atoms remain unpaired with pi-bonds. The high-pressure form is superhard, capable of indenting cubic-diamond single crystals.
    [Abstract] [Full Text] [Related] [New Search]