Defects in Carbon Nanostructures

TLDR

HREM studies of carbon nanotubes suggested a Russian‑doll model of hollow concentric cylinders capped at both ends. The authors characterized the nanotube structures and particles using bulk physical and chemical property measurements. The nanostructures are as compressible as graphite along the c‑axis, can be intercalated with K and Rb to MC(8), and exhibit electronic properties distinct from graphite; HREM reveals a paper‑mache arrangement of smaller graphite layers, contradicting the Russian‑doll model, while bulk measurements show they are highly defective with a local structure resembling turbostratic graphite.

Abstract

Previous high-resolution electron microscopy (HREM) observations of the carbon nanotubes have led to a "Russian doll" structural model that is based on hollow concentric cylinders capped at both ends. The structures of the carbon nanotubes and particles were characterized here by bulk physical and chemical property measurements. The individual nanostructure is as compressible as graphite in the c axis, and such nanostructures can be intercalated with potassium and rubidium, leading to a saturation composition of "MC(8)." These results are counter to expectations that are based on a Russian doll structure. HREM after intercalation with potassium and deintercalation indicates that individual nanoparticles are a "paper-mache" of smaller graphite layers. Direct current magnetization and electron spin resonance measurements indicate that the electronic properties of the nanostructures are distinctly different from those of graphite. Although the nanostructures have distinct morphologies and electronic properties, they are highly defective and have a local structure similar to turbostratic graphite.