Magnetic Fe catalyst particles in the vapor-phase-grown multi-walled carbon nanotubes

摘要

Control of the magnetic Fe catalyst particle size encapsulated in multi-walled carbon nanotubes (MWNTs) was obtained by means of the vapor-phase growth employing different reaction gas flow rates. According to our structural and magnetic investigation, the magnetic encapsulation in the MWNTs consists of alpha-Fe core particles and interfacial Fe3C surrounding them. Characteristic alpha-Fe particle size dependence of the coercivity was revealed, and the coercivity as well as the anisotropy were shown to be dictated by the interfacial Fe3C. (C) 2008 Elsevier Ltd. All rights reserved.