Nanocrystalline diamond synthesized from C60

Bayerisches Geoinstitut, Universität Bayreuth, Universittstrasse 30, 95440 Bayreuth, Germany
Diamond and Related Materials (Impact Factor: 1.71). 11/2010; DOI: 10.1016/j.diamond.2004.06.017

ABSTRACT A bulk sample of nanocrystalline cubic diamond with crystallite sizes of 5–12 nm was synthesised from fullerene C60 at 20(1) GPa and 2000 °C using a multi-anvil apparatus. The new material is at least as hard as single crystal diamond. It was found that nanocrystalline diamond at high temperature and ambient pressure kinetically is more stable with respect to graphitisation than usual diamonds.

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    ABSTRACT: a b s t r a c t The growth of diamond from fullerene C60 was studied by spark plasma sintering (SPS). The phases and microstructures were analyzed by Raman spectroscopy, Synchrotron X-ray, scanning electron micro-scopy and transmission electron microscopy. Experimental results show that C60 becomes unstable and can be directly transformed into diamond by SPS under a pressure of 50 MPa at temperatures above 1150 1C, without any catalyst being involved. Polycrystalline diamond crystals with sizes up to 250 mm and transition rate about 30 vol% are obtained at SPS temperature of 1300 1C. The mechanism indicates that the high fraction of sp 3 hybrids in the fullerene C60 and the generated plasmas in the SPS lead to its transformation into diamond at such low temperatures and pressures. The transformation from C60 to diamond is a direct transition process with a structural reconstruction of carbon atoms without intermediate phases being involved.
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    ABSTRACT: A brief review has been presented of the recent studies aimed at searching for new 3D (sp3) carbon allotropes of increased hardness and carried out using computational approaches. The principles of the construction of structural models, methods of the analysis of stability and assessments of microhardness of novel carbon materials have been considered.
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    ABSTRACT: In the present work in experiments in a diamond anvil cell at room temperature we studied the behavior of glassy carbon under high pressure up to 60 GPa by means of in situ Raman spectroscopy. Raman bands typical for glassy carbon were clearly observed in the entire pressure interval. We did not see any noticeable changes in the type of chemical bonding in glassy carbon up to the highest pressure reached. The yield strength of the material under confining pressure was found to be maximum of about 7 GPa, inconsiderably higher than that measured at ambient pressure (1.4 GPa on literature data).
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