Interface structure of niobium carbide-encapsulating carbon nanocapsules studied by high-resolution transmission electron microscopy.

Carbon nanocapsules (CNCs) encapsulating niobium carbide (NbC) crystals with a sodium chloride structure were synthesized via a gas-evaporation method by arc-discharge heating. CNCs were observed by high-resolution transmission electron microscopy, and the atomic configurations at the graphene/NbC interfaces were investigated. The NbC crystals within the nanospaces of CNCs were truncated by the {100}, {110}, and (111} facets and were coated with several graphene layers. It was found that the interlayer spacings for the graphene{0001}/NbC{100} and graphene{0001}/NbC{110} interfaces were 0.33 +/- 0.05 nm, whereas those for the graphene{0001}/{111}NbC interfaces were 0.28 +/- 0.05 nm.