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

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.

Colloidal transport and diffusion over a tilted periodic potential: dynamics of individual particles

“…Equation (1) provides a simple physical picture for a common class of diffusive barrier-crossing problem. Understanding the effect of the external force on thermally activated kinetics is a concern of a common class of transport problem, such as particle separation by electrophoresis [17,18], electromigration of atoms on the surface of metals [19] and semiconductors [20], motion of a three-phase contact line under the influence of an unbalanced capillary force [21], control of crystal growth [22] and design of nano-scale machineries [23,24]. The diffusive barrier crossing is made under constant thermal agitations and the probability for such random events to occur becomes very small if E b is much larger than the thermal energy k B T .…”

Colloidal dynamics over a tilted periodic potential: Nonequilibrium steady-state distributions

“…Similar attempts have also been made in the study of colloidal transport and diffusion in a 1D optical trap (optical tweezers) with either a periodic or random variation of the laser light intensity [21][22][23][24]. Understanding the effect of the external force on thermally activated kinetics is a concern of a common class of transport problem, such as particle separation by electrophoresis [25,26], electromigration of atoms on the surface of metals [27] and semiconductors [28], motion of a three-phase contact line under the influence of an unbalanced capillary force [29], control of crystal growth [30], and design of nanoscale machineries [31,32]. In biology and biophysics, force-assisted thermal activation is employed in various single-molecule stretching experiments to study the binding and folding energy landscape of biomolecules, such as DNA [33], RNA [34], nucleic acids [35], receptors and ligands [36], and proteins [37], and the adhesion between biomembranes of vesicles, capsules, and living cells [38,39].…”

A carbon-nanotube based nano-furnace for in-situ restructuring of a magnetoelectric oxide

“…During I-V scan, current first rises with increasing voltage and reaches a peak value "I P " at a critical voltage "V P ". For the CNT shown in In case of a metal filled CNT, such as Fe filled CNT reported in literature [13][14][15] , the Joule heating driven temperature rise influences the graphitic shells of the CNT as well as the metallic encapsulate, which is seen to melt and move during I-V scans [13][14][15] .…”

“…We also emphasize that while a significant amount of work has also been carried out on the encapsulation of metals inside CNT [11][12][13][14][15] , I-V characteristics have mostly been reported for Fe-filled CNT, where the focus has primarily been on deciphering the mechanism of mass transport in femtogram scales, and the utility of metal-filled CNT as a nano pippet [13][14][15] in which the magnetism can be tuned via an electric field [22][23][24] . Upon nanoscaling, it is seen to M A N U S C R I P T…”

“…Probing the I-V characteristics of individual carbon nanotubes [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] has been a subject of intense investigations since it is crucial for their integration into miniaturized devices.…”