Heat transport in pristine and polycrystalline single-layer hexagonal boron nitride

Abstract

We use a phase field crystal model to generate large-scale bicrystalline and polycrystalline single-layer hexagonal boron nitride (h-BN) samples and employ molecular dynamics (MD) simulations with the Tersoff many-body potential to study their heat transport properties. The Kapitza thermal resistance across individual h-BN grain boundaries is calculated using the inhomogeneous nonequilibrium MD method. The resistance displays strong dependence on the tilt angle, the line tension and the defect density of the grain boundaries. We also calculate the thermal conductivity of pristine h-BN and polycrystalline h-BN with different grain sizes using an efficient homogeneous nonequilibrium MD method. The in-plane and the out-of-plane (flexural) phonons exhibit different grain size scalings of the thermal conductivity in polycrystalline h-BN and the extracted Kapitza conductance is close to that of large-tilt-angle grain boundaries in bicrystals.

Influence of thermostatting on nonequilibrium molecular dynamics simulations of heat conduction in solids

“…This is why previous works [20,24] using Eq. (27) can get agreement between NEMD and other methods in the diffusive regime. However, when L is relatively short (compared to the average phonon mean free path), using Eq.…”

“…The relative errors caused by using Eqs. (28) and (27) decrease with increasing system length L. If one focuses on the diffusive regime with relatively long systems, using Eq. (27) will not result in large errors.…”

“…However, when L is relatively short (compared to the average phonon mean free path), using Eq. (27) in NEMD simulations will result in large errors.…”

Thermal conductivity reduction in carbon nanotube by fullerene encapsulation: A molecular dynamics study

“…The simulation cell in the HNEMD method is the same as that in the EMD method [25]. It is conventional to examine the cumulative average of the thermal conductivity as a function of time in the production stage [25,[48][49][50][51]. The results for a C 60 @(10, 10) CNP and a (10, 10) SWCNT are shown in Figs.…”

“…The thermal conductivity component due to the convective part of the heat current is κ con ≈ 0.3 ± 5.7 W/mK, which is essentially zero in agreement with the EMD simulations. Note that the total production time in the HNEMD simulations is shorter than that in the EMD simulations and the statistical error is smaller, reflecting the higher efficiency of the HNEMD method over EMD [25,50,51].…”