Thermal transport across symmetric tilt grain boundaries in β-SiC: Effect of dopants and temperature

The Kapitza resistance at a segregated, low-angle symmetric tilt grain boundary in β-SiC is investigated using non-equilibrium molecular dynamics simulation. In particular, we assess the role of compositional and thermal disorder on the boundary resistance for various doping scenarios. By examining the local vibrational density of states, we identify a subset of modes that are significant for thermal transport in this system. This analysis is complemented by calculations of the projected density of states and a corresponding eigenmode analysis of the dynamical matrix that highlight important phonon polarizations and propagation directions. We also examine the dependence of the Kapitza resistance on temperature and dopant/matrix interaction strength, the latter parameter affecting grain-boundary structure and, hence, phonon scattering.