RESEARCH PAPER Formation of bamboo-shaped carbon nanotubes on carbon black in a fluidized bed Kinshuk Dasgupta • D. Sen • T. Mazumdar • R. K. Lenka • R. Tewari • S. Mazumder • J. B. Joshi • S. Banerjee Received: 7 June 2011 / Accepted: 6 January 2012 Ó Springer Science+Business Media B.V. 2012 Abstract For the first time, bamboo-shaped multi- walled carbon nanotubes, having diameter of the order of 50 nm, have been grown on carbon black in a fluidized bed in bulk amount. The activation energy for the synthesis of the product was found out to be around 33 kJ/mol in the temperature range of 700-900 °C. The carbon nanotubes were separated from the carbon black by preferential oxidation of the later, the temper- ature of which was determined by thermogravimetry. The transmission electron microscopy revealed different features of the nanotubes such as ‘‘Y’’ junction, bend, and catalyst filling inside the nanotubes. Small angle neutron scattering was performed on the nanotubes synthesized at different temperatures. The data were fitted into a suitable model in order to find out the average diameter, which decreases with increase in synthesis temperature. The Monte Carlo simulation predicts the same behavior. Based on the above observations, a possible growth mechanism has been predicted. The oscillation in carbon saturation value inside the catalyst in the fluidized bed has been indicated as the responsible factor for the bamboo-shaped structure. Keywords Carbon nanotube  Fluidized bed  Electron microscopy  Small angle neutron scattering  Modeling and simulation Introduction In recent years, carbon nanotube (CNT) has drawn attention of the researchers, due to its unique properties and potential applications in the electronic industries, in power generation and storage, in biomedical applica- tion, in structural and functional composites, etc. (Baughman et al. 2002; Bonard et al. 2001; Dillon et al. 1997; Fan et al. 2006; Tans et al. 1997; Tsukagoshi et al. 2002). The bulk production of CNTs in an economic way is the route to feasibility of these applications. Out of different techniques, catalytic chemical vapor deposition in a fluidized bed is the most promising technique for bulk production of this exotic K. Dasgupta  R. K. Lenka  R. Tewari Materials Group, Bhabha Atomic Research Centre, Mumbai 400085, India e-mail: kdg@barc.gov.in; dasguptakinshuk@yahoo.com K. Dasgupta  J. B. Joshi (&) Department of Chemical Engineering, Institute of Chemical Technology, Mumbai 400019, India e-mail: jb.joshi@ictmumbai.edu.in; jbjoshi@gmail.com D. Sen  S. Mazumder Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India T. Mazumdar Research Reactor Services Division, Bhabha Atomic Research Centre, Mumbai 400085, India J. B. Joshi  S. Banerjee Homi Bhabha National Institute, Mumbai 400094, India S. Banerjee Department of Atomic Energy, Mumbai 400001, India 123 J Nanopart Res (2012) 14:728 DOI 10.1007/s11051-012-0728-5