The Apex Structure of Co-Produced Helical Boron Nitride and Carbon Cones

Abstract

Conical whiskers of layered compounds such as graphite and hexagonal boron nitride (h-BN)2 are interesting materials because their conical morphology results from the introduction of a local topological defect at the cone apex. In the honeycomb array characteristic of graphite and h-BN basal planes, this topological defect is thought to be a non-hexagonal ring (e.g. a pentagon or a square). These defects are known to form the basis of curved nanostructures like fullerenes and buckytubes. Therefore a comparison of their occurrence in two systems known to harbour nanostructures is worthy of study.The defect structure at the apex of co-produced carbon and boron nitride whiskers was investigated by analytical transmission electron microscopy (TEM). The instrument used was a field-emission JEM3000F high-resolution electron microscope, equipped with a parallel electron energy loss spectrometer (EELS).