Thermal transport in silicene nanotubes: Effects of length, grain boundary and strain

Abstract

Thermal transport behavior in silicene nanotubes has become more important due to the application of these promising nanostructures in the engineering of next-generation nanoelectronic devices. We apply non-equilibrium molecular dynamics (NEMD) simulations to study the thermal conductivity of silicene nanotubes with different lengths and diameters. We further explore the effects of grain boundary, strain, vacancy defect, and temperature in the range of 300-700 K on the thermal conductivity. Our results indicate that the thermal conductivity varies with the length approximately in the range of 24-34 W/m.K but exhibits insensitivity to the diameter and chirality. Besides, silicene nanotubes consisting of the grain boundary exhibit nearly 30% lower thermal conductivity compared with pristine ones. We discuss the underlying mechanism for the conductivity suppression of the system consisting of the grain boundary by calculating the phonon power spectral density. We find that by increasing the defect concentration and temperature, the thermal conductivity of the system decreases desirably. Moreover, for strained nanotubes, we observe unexpected changes in the thermal conductivity, so that the conductivity first increases significantly with tensile strain and then starts to decrease. The maximum thermal conductivity for the armchair and zigzag edge tubes appears at the strains about 3% and 5%, respectively, which is about 28% more than that of the unstrained structure.

Phonon thermal conductivity reduction in silicene nanotubes with isotope substitution

“…Using this approach, the k N value of individual armchair SNT is extrapolated to be 38.5 W mK À1 , which is one order of magnitude lower than that of bulk silicon crystal. Also, the calculated phonon mean-free path (MFP) for an innite armchair SNT is about 14.7 nm, which is consistent with the previous results of 13.5 nm for armchair SNT by MD simulations 24 and about 24 nm for silicene by rst principle calculations, 35 respectively.…”

“…Tersoff potential 29 was used to describe the Si-Si bonding interaction in the simulation systems, and successfully utilized in the simulation of the structural and phonon properties of SNT. 16,24 The structural optimization was performed using the Polak-Ribière version of the conjugated gradient algorithm. Fig.…”

“…17 Then the simulation is carried out according to the standard process described in the literature. 24,30,31 Initially, 1 ns Nose-Hoover thermo bath coupling 32 (coupling constant 0.1 ps) with a background temperature of 300 K were conducted to achieve equilibrated structures. Aer the equilibrium state was achieved, the microcanonical ensemble is adopted and NEMD simulations are performed to investigate the thermal transport behavior.…”

“…[20][21][22][23] Despite extensive studies on the electronic and thermal features of silicene nanoribbons, minimal research has been devoted to date to the thermal (phonon) transport of silicene nanotubes (SNTs). 24 Previous studies have shown that isotope impurities provide a powerful technique to modulate the phonon-related properties of carbon nanotubes (CNTs), 25 graphene, 26 and silicon nanowires. 27 Isotope doping easily introduces phonon-defect scattering in nanostructures without damaging the electronic quality, thereby attracting intensive interest among researchers.…”

Thermal conductivity and thermal rectification of nanoporous graphene: A molecular dynamics simulation

“…Also, phonon density of state (DOS) was obtained via calculating Fourier transformation of the velocity autocorrelation (indicated by < >) using the equation below [28],…”