Plasticity of Cu nanoparticles: Dislocation-dendrite-induced strain hardening and a limit for displacive plasticity.

The plastic behaviour of individual Cu crystallites under nanoextrusion is studied by molecular dynamics simulations. Single-crystal Cu fcc nanoparticles are embedded in a spherical force field mimicking the effect of a contracting carbon shell, inducing pressure on the system in the range of gigapascals. The material is extruded from a hole of 1.

Defect-induced junctions between single- or double-wall carbon nanotubes and metal crystals.

Interfaces between the ends of single- or double-wall carbon nanotubes and metal crystals (Fe, Co, Pd, and Pt) are established by electron irradiation with nanometre precision at metal-nanotube contact areas. Calculations of the bonding energies at the metal-nanotube interfaces confirm that the formation of these covalent junctions is energetically favourable in the presence of a certain concentration of structural defects in the nanotubes. The process may be endothermic or exothermic in comparison with the unconnected configuration, but in either case atomic defects in carbon nanotubes are a necessary condition for joining them with metals.

Growth of single-walled carbon nanotubes from sharp metal tips.

The nucleation and growth of single-walled carbon nanotubes is observed in situ in a transmission electron microscope. Carbon atoms are implanted into catalytically active metal particles by electron-beam sputtering. The metal particles are then shaped with a focused electron beam.