Microstructure and microscopic deposition mechanism of twist-shaped carbon nanocoils based on the observation of helical nanoparticles on the growth tips

• Published in: Carbon (New York) 2005, Vol.43 (5), p.916-922
• Main Authors: Yang, S., Chen, X., Kusunoki, M., Yamamoto, K., Iwanaga, H., Motojima, S.
• Format: Article
• Language: English
• Subjects: Carbon microcoils; Catalyst; Chemical vapor deposition; Chemistry; Colloidal state and disperse state; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; General and physical chemistry; Materials science; Microstructure; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Physics; Specific materials; Transmission electron microscopy
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2004.11.040

Carbon nanocoils possessing a twisting form were prepared from an Fe-based alloy (SUS410) catalyst, the crystallographic properties of the catalyst surface, which was present on the growth tip, were examined, and a novel growth mechanism of the nanocoils is presented. Single-helix twisted carbon nanocoils with a coil diameter of 300–400 nm were obtained at 700–800 °C with a yield of 60% and a purity of nearly 100%. The catalyst structure observed on the growth tip was a Fe 5C 2 (monoclinic) or Fe 7C 3 (orthorhombic) single crystal, in which some of the Fe atoms were substituted by Cr. Carbon nanoparticles with a helical structure were observed on the surface of catalyst particle. It is considered that the carbon nanoparticles are a helical carbon supply source. That is, the catalyst particle supplies microscopic carbon nanoparticles by helical deposition patterns on the catalyst surface to form macroscopic helical patterns of carbon nanocoils.