SUPERHARD AND ELASTIC CARBON NITRIDE THIN-FILMS HAVING FULLERENE-LIKEMICROSTRUCTURE

CNx films were found to have a distorted graphitelike microstructure c onsisting of buckled and curved basal planes using high-resolution ele ctron microscopy. Nanoindentation showed an elastic recovery of 85%, a nd a hardness of similar to 60 GPa. Based on detailed quantum chemical calculations and photoelectron spectroscopy, the observed structure i s proposed to consist of a network of buckled sp(2)-hybridized CNx pla nes, cross-linked by sp(3)-hybridized bonds. The buckling is shown to be due to the incorporation of pentagons in the basal planes, giving r ise to a fullerenelike microstructure.