Kapitza conductance of symmetric tilt grain boundaries of monolayer boron nitride

Abstract

We use reverse nonequilibrium molecular dynamics simulations to study thermal conductivity of two–dimensional hexagonal boron nitride (h–BN) nanoribbons containing symmetric tilt grain boundaries. The simulations are conducted on periodic h–BN nanoribbons with zigzag and armchair chirality. The effective thermal conductivity of ribbons and Kapitza conductance of grain boundaries are calculated by inducing a constant heat flux along the longitudinal direction of ribbons. The steady state temperature profiles of nanoribbons display jumps at the location of grain boundaries. The temperature jumps monolithically increases with the misorientation angle of grain boundaries indicating that grain boundaries with higher misorientation angle have lower Kapitza conductance. The lower Kapitza conductance is due to higher phonon scattering at grain boundaries which is a result of a higher mismatch between the phonon spectra of grain boundary and grain atoms. Our modeling results also predict that by increasing the length, both Kapitza conductance of grain boundaries and effective thermal conductivity of ribbons increases. Although temperature does not have a significant impact on Kapitza conductance, but by increasing temperature effective thermal conductivity of ribbons decreases.