The melting and freezing of KI nanoparticles confined within zigzag single-walled carbon nanotubes based on molecular dynamics simulations

Abstract

We have applied MD simulation method to investigate the structure, phase transition, and nucleation of KI nanoparticles confined in zigzag single-wall carbon nanotubes ((n,0)-SWNTs). SWNTs are approximately handled to be rigid. The ion–ion interactions are represented by Born–Mayer–Huggins’ potential and the KI-SWNT interactions are described by Lennard–Jones potential. The total energies, structures, and Lindemman indices reveal the feature of phase transition for KI nanoparticles confined in (n,0)-SWNTs. The nucleation analysis is carried out by classical nucleation theory. Results demonstrate that the structures of the confined (KI)N nanoparticles are very sensitive to the length of KI nanoparticles and tube diameter and the confined KI nanoparticles have multishelled or FCC structures. Interestingly, on the cross section perpendicular to the tube axis, the arrangement of K+ and I− ions exhibits some quasi-five-membered rings, which may be related to geometrical match between KI ionic radii and tube diameter, and confining effect of SWNT. In addition, some important thermodynamic and dynamic parameters are derived and compared with available experimental and calculated results.