physica status solidi (b) · 2010 · 56 citations · 12 references
Natural SciencesMaterials EngineeringMaterials ScienceMaterials ChemistryNanomaterialsNanotechnologyCarbon NanomaterialsCarbon NanotubesCatalyst CharacterizationCatalytic Reaction EngineeringNanotubesThermodynamics Of NanomaterialsCarbon CatalystsCarbon Nanotube CharacterizationCarbon-based CatalystsDebye ModelMulti-walled Carbon NanotubesPurity CharacterizationPurity ControlThermal Conductivity Of Nanotubes
Abstract Here multi‐walled carbon nanotubes (MWNT) of different average diameters with ppm level purity were produced by a low temperature C 2 H 4 pyrolysis on Fe‐Co type catalysts combined with forthcoming graphitization at 2200–2800 °C in argon flow. Annealed nanotubes were characterized with X‐ray fluorescent analysis, BET surface measurements, HR TEM, X‐ray diffraction, DTA analysis, and measurements of temperature and magnetic field dependences of conductivity. The graphitization of MWNT results in removal of residual catalyst metal impurities, reduction of the wall defects, and closure of nanotube tips. It was found that extent of these effects depends on MWNT diameters. It was proposed that the graphitization is caused by a significant thermal displacement and diffusion of carbon atoms at temperatures higher the Debye temperature.
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Vapor-grown carbon fibers (VGCFs)
Morinobu Endo, Yoong Ahm Kim, T Hayashi et al. · Carbon · 2001 · 556 citations
Natural Sciences, Materials Engineering, Materials Science +9
Annealing effect on disordered multi-wall carbon nanotubes
Yoong Ahm Kim, T. Hayashi, Kozo Osawa et al. · Chemical Physics Letters · 2003 · 114 citations