Transmission of phonons through grain boundaries in diamond films

Abstract

The influence of grain boundary scattering of lattice waves in high quality diamond films has been determined by the measurement of thermal conductivity down to 0.15 K. We find that the mean free path for lattice vibrations (phonons) exceeds substantially the crystallite size and approaches the physical size of the sample. This implies that a significant transmission of phonons occurs between the grains of these polycrystalline diamond materials.