Kapitza resistance at segregated boundaries in β-SiC

Abstract

The impact of grain-boundary segregation on the high-temperature Kapitza resistance of doped β-SiC using non-equilibrium molecular dynamics simulation is investigated. In particular, low-angle, symmetric tilt grain boundaries are examined to assess the roles of dopant concentration and dopant/matrix interaction strength in determining the resistance. For relatively weak interaction strengths, dopant clustering predominates, and the Kapitza resistance increases significantly for small changes in dopant concentration. As the dopant/matrix interaction strength is increased, dopant layering is observed with a concomitant gradual increase in resistance with concentration. The different interaction strength regimes are investigated by mapping the spatial distribution of boundary temperatures and by quantifying the degree of spatial ordering at a boundary. It was found that dopant clustering leads to a heat flux parallel to the grain-boundary plane and to significant boundary disorder, partly explaining the observed increase in Kapitza resistance at the boundary.