Anisotropy of thermal expansion of helically coiled carbon nanotubes

Abstract

Four types of linear thermal expansion coefficients of helically coiled carbon nanotubes (radial tubular, axial tubular, helical radial and helical axial) are numerically evaluated by minimizing Helmholtz free energy at fixed temperatures. Isotropy of thermal expansion of tubular parameters and high anisotropy of thermal expansion of the coil parameters are predicted. The latter is interpreted by spring like behavior and extreme elasticity of helically coiled carbon nanotubes. Brenner interatomic potential for carbon is used. Applied also is the line group symmetry which together with Hooke–Jeeves algorithm made the calculations highly efficient.

Thermal Conductance of Helically Coiled Carbon Nanotubes

“…Dynamical sub-matrices of each atom in symmcell of relaxed HCCNTs are obtained numerically. Every force constant is evaluated by changing Brenner's interatomic potential energy [7] during variation of spatial coordinates of carbon atom [8,9].…”

Crossover from ballistic to diffusive thermal conductance in helically coiled carbon nanotubes

“…Due to the spring‐like structure, helically coiled carbon nanotubes (HCCNTs) are extremely elastic (). Had the coiled nanotubes also good thermal conduction properties, they would be better candidates for thermal management applications than straight CNTs.…”