Enhanced reduction of thermal conductivity across kink dislocation textures in magnesium oxide

Abstract

Our understanding on how dislocation textures quantitatively affect thermal conductivity has been limited. We investigate the impact of kink dislocations on phonon thermal conduction in MgO by molecular dynamics, through changing edge and screw components in kink dislocations. The thermal conductivity is almost independent of the length of the edge component, but is rather reduced significantly with increasing the length of screw component, resulting in lower thermal conductivity than perfect edge dislocations. This reveals the combined effect of the edge and screw components on thermal conductivity beyond the simple description as one-dimensional obstacles and linear elastic strain field. Atomic contributions to thermal conductivity show that not only atoms in the vicinity of the kink dislocation cores but also those away from the cores exhibit suppressed thermal conductivity compared to the perfect edge dislocations. These results indicate that it is possible to efficiently reduce thermal conductivity in complex dislocation textures in real materials.