HARD ELASTIC CARBON THIN-FILMS FROM LINKING OF CARBON NANOPARTICLES

HARD carbon thin films find many technological applications-as protect ive or biocompatible coatings, for instance, A very hard and elastic f orm of carbon nitride, in which curved graphene sheets are interlinked owing to the presence of small amounts of nitrogen, has recently been reported(1). The hardness of these films is thought to arise from the presence of sp(3)-like bonds that introduce curvature into and bind t ogether the sp(2)-bonded graphitic planes, rather as they do in hard, highly tetrahedrally bonded amorphous carbon films(2-4). Here we show that hard, elastic thin films of pure carbon can be created by deposit ing closed, hollow graphitic carbon nanoparticles-nanotubes(5) and car bon onions(6)-onto a substrate at high velocity, The particles are app arently disrupted on impact, causing them to link up, Electron-energy- loss spectra reveal a reduction in pi (sp(2)) bonding in the intersect ing regions of the nanoparticles, supporting the idea that they are co valently linked by tetrahedral sp(3) bonds.