Kinematics of electromigration-driven sliding of Co nanorod fillers inside multi-walled carbon nanotubes

The movement of Co nanorods driven by electromigration inside multi-walled carbon nanotubes was observed using in situ transmission electron microscopy. This study provides a unique method of experimental determination of both the electromigration force strength and sliding friction. When the tip of a biased electrode was located within the portion of a Co nanorod filler and an electric current was applied to push a part of the Co filler along the flow of electrons, the Co filler showed a trigonometric motion. Both the electromigration force strength and sliding friction were determined by analysis of the trigonometric movements. When a reversed electric current was applied to pull a part of the Co nanorod filler, its motion was hyperbolic-cosine like, and the motion was not suitable to determine the strengths of the two forces. Our method and the results would be useful for the development of the methods to precisely control mass transfer at the nanoscale.