Growth of diamond from fullerene C60 by spark plasma sintering

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 microscopy 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 degrees C, without any catalyst being involved. Polycrystalline diamond crystals with sizes up to 250 mu m and transition rate about 30 vol% are obtained at SPS temperature of 1300 degrees C. 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. (c) 2011 Elsevier B.V. All rights reserved.