J.B. Wang

Buckling behaviors of single-walled carbon nanotubes filled with metal atoms

Molecular dynamics method is employed to investigate the buckling deformations of single-walled carbon nanotubes(SWCNTs) filled with nickel(Ni),copper(Cu), and platinum (Pt) atoms under axial compression. The critical buckling strains of filled tubes decrease linearly before a critical number of metal atoms and then increase linearly when more atoms are encapsulated. For SWCNT completely filled with metals, its critical strain is larger than that of the hollow tube. Furthermore, the critical strain of SWCNT completely filled with Ni atoms is larger than that of the tube fully filled with Cu or Pt atoms.

Formation of two conjoint fivefold deformation twins in copper nanowires with molecular dynamics simulation

The formation of two conjoint fivefold deformation twins (DTs) in copper nanowires under bending is reported based on molecular dynamics simulations. It is found that an intermediate icosahedral phase is formed to facilitate the transformation from a low dense (010) plane in a face-centered-cubic lattice to a {111} close-packed fashion, forming trijunctions composed of three DTs. These trijunctions can easily interact with other DTs, forming two conjoint fivefold DTs. This formation process differs from the one observed by Cao and Wei [Appl. Phys. Lett. 89, 041919 (2006)], that is, fivefold DTs could be formed without introducing initial imperfections in simulations.

Single-walled carbon nanotubes filled with bimetallic alloys: Structures and buckling behaviors

Structural and mechanical properties of single-walled carbon nanotubes (SWCNTs) completely filled with bimetallic alloys are investigated using classic molecular dynamics method. Progresses on both synthesis and property researches of metal-filled carbon nanotubes are also comprehensively reviewed. Different initial equilibrium structures and buckling behaviors are exhibited for tubes filled with alloys of different species and compositions. The critical buckling strain of a SWCNT filled with mixed metals can be higher than that of the tube encapsulated with any pure component metals. Strong dependencies of buckling deformations on the initial random distributions of the encapsulated alloy metals are also reported.

Pressure control model for transport of liquid mercury in carbon nanotubes

Carbon nanotubes have a significant application in nanotechnology as nanopipes conveying fluids. In this letter, a pressure control model for transport of liquid mercury through carbon nanotubes using classical molecular dynamics simulations in conjunction with an atomistic model is presented. Wetting of single-walled carbon nanotubes by mercury occurs above a threshold pressure of liquid mercury. The liquid mercury can be transported through carbon nanotubes with the continuous increase of its internal pressure. Also, the authors show that single-walled carbon nanotubes can transport liquid mercury discontinuously when a periodical pressure is applied on the liquid.

Nanopore density effect of polyacrylamide gel plug on electrokinetic ion enrichment in a micro-nanofluidic chip

In this paper, the nanopore density effect on ion enrichment is quantitatively described with the ratio between electrophoresis flux and electroosmotic flow flux based on the Poisson-Nernst-Planck equations. A polyacrylamide gel plug is integrated into a microchannel to form a micro-nanofluidic chip. With the chip, electrokinetic ion enrichment is relatively stable and enrichment ratio of fluorescein isothiocyanate can increase to 600-fold within 120 s at the electric voltage of 300 V. Both theoretical research and experiments show that enrichment ratio can be improved through increasing nanopore density. The result will be beneficial to the design of micro-nanofluidic chips.

Buckling Behaviors of Double-Walled Carbon Nanotubes with Abnormal Interlayer Distances

Several double-walled carbon nanotubes (DWCNTs) composed of internal and external single-walled carbon nanotubes (SWCNTs) with different chirality are presented and simulated by the molecular dynamics (MD) method. Both armchair-armchair and zigzag-zigzag patterns are included. Interlayer distances of the novel DWCNTs are different with 0.34nm of the normal DWCNTs. The interaction between atoms within each tube and the van der Waals force between inner and outer walls are respectively described by the Tersoff-Brenner potential and the Lennard-Jones potential. Firstly, the initial equilibrium structure of each DWCNT is achieved after free relaxation over a long period of time. It should be noted that no any constraint is fixed during the free relaxation process. Then their buckling modes and changes of strain energy under uniaxial compression are simulated to examine the influence of the van der Waals force on the mechanical properties of the novel DWCNTs. Numerical results show that the different van der Waals force coming from different interlayer spacing results in different critical buckling strain of the novel DWCNT under uniaxial compression. It is found that the buckling behaviors of armchair-armchair DWCNTs are similar with but not completely the same as those of zigzag-zigzag DWCNTs. The novel DWCNTs whose interlayer spacings are less than 0.34nm exhibit better compressive stability as compared with the normal DWCNT.