Surface Morphology and Composition of a NbC/C Composite Studied by Scanning Electron Microscopy and X-Ray Photoelectron Spectroscopy

— The surface morphology and composition of a NbC/C composite prepared via thermal decomposition of the products of reaction between NbCl 5 and acetylene [9] have been studied by scanning electron microscopy and X-ray photoelectron spectroscopy. The results demonstrate that the NbC thus synthesized consists of nanocrystals. The surface layer of the NbC/C composite contains nine carbon atoms per Nb atom. The niobium is present in the form of the NbC carbide (33%) and the NbO 2 (10%) and Nb 2 O 5 (57%) oxides, with Nb 3 d 5/2 electron binding energies of 203.8, 205.0, and 207.2 eV, which are tentatively attributed to Nb 2+ (NbC), Nb 4+ , and Nb 5+ ions, respectively. The presence of NbO 2 and Nb 2 O 5 in the surface layer is due to active reaction of the NbC/C composite with atmospheric oxygen and moisture during the sample preparation process. Our results on the structure of the C1 s electron spectra lead us to assume that the carbon on the surface of the composite particles has the form of a graphene-like carbon material. The composite does not become charged when exposed to an X-ray beam, which suggests that it is a weak dielectric.