In-situ monitoring of iron nanoparticles movement and graphitization control by Joule heating at local current injection

In-situ monitoring is a powerful tool for understanding the nanotube growth mechanism. We previously reported the solid phase nanotube growth that was observed in an amorphous carbon pillar associating with the movement of iron particles (Fujita et al., 2004; Ichihashi et al., 2004), where our real-time TEM image revealed that the nanotube was exhausted at the tail of the iron particle as migrating of the iron particle into the solid amorphous carbon pillar with heating in vacuum. In contrast, Joule heating for ready made nanotube containing catalyst also induced the additional nanotube growth inside of the original one, and/or repairing the defects through solid phase reaction (Jensen et al., 2005). In this paper, we report our detailed analysis of iron particle movement in amorphous carbon and the control method of the iron particle movement by using Joule heating.