Structural property-induced different phonon-twin-boundary scattering in diamond.

Abstract

Twin boundaries (TBs), as one kind of crystal defect, have often been observed in various material systems, and the (111)/[110] TB has been verified to show weak phonon scattering. However, it's still not clear whether other TBs can show similar thermal properties to the (111)/[110] TB. To solve this issue, in this work, we perform a systematic study of heat transport across six kinds of twin boundaries in diamond, including the (111)/[110], (221)/[110], (331)/[110], (113)/[110], (112)/[110] and (310)/[001] TBs, by both molecular dynamics simulations and first-principles calculations. The results indicate that the thermal boundary resistance of the six TBs ranges from 1.01 × 10-11 to 6.35 × 10-10 m2 K W-1; specifically, the (111)/[110] TB shows much weaker phonon scattering than the others. The different phonon scattering at TBs mainly depends on the transmission coefficients across the twin boundaries for boundaries with the same symmetry, as well as the combined action of group velocity and phonon mean free path. Furthermore, by analyzing the structural properties of TBs, it can be observed that TB thermal resistance varies significantly with the TB structure, and is strongly correlated with TB energy and bond difference parameter. Our findings will provide useful guidelines for designing efficient thermoelectric and thermal management materials based on phonon-TB scattering.