Surface Atom Motion to Move Iron Nanocrystals through Constrictions in Carbon Nanotubes under the Action of an Electric Current

TL;DR

This study demonstrates how iron nanocrystals can be transported through constrictions in carbon nanotubes under electric current, revealing surface atom motion as the key mechanism, with potential applications in nanomechanics and nanoparticle synthesis.

Contribution

It provides experimental and theoretical insights into nanocrystal movement through constrictions, highlighting a surface atom rearrangement mechanism that is largely independent of various parameters.

Findings

Nanocrystals remain solid and crystalline during passage.

Surface atom motion enables nanocrystal transport through constrictions.

Model predicts movement through complex geometries.

Abstract

Under the application of electrical currents, metal nanocrystals inside carbon nanotubes can be bodily transported. We examine experimentally and theoretically how an iron nanocrystal can pass through a constriction in the carbon nanotube with a smaller cross-sectional area than the nanocrystal itself. Remarkably, through in situ transmission electron imaging and diffraction, we find that, while passing through a constriction, the nanocrystal remains largely solid and crystalline and the carbon nanotube is unaffected. We account for this behavior by a pattern of iron atom motion and rearrangement on the surface of the nanocrystal. The nanocrystal motion can be described with a model whose parameters are nearly independent of the nanocrystal length, area, temperature, and electromigration force magnitude. We predict that metal nanocrystals can move through complex geometries and constrictions, with implications for both nanomechanics and tunable synthesis of metal nanoparticles.