Phonon Diffraction and Dimensionality Crossover in Phonon-Interface Scattering
Abstract
This theoretical work provides several mechanistic understandings of phonon-interface scattering. The treatment provided here defines the interface as an array of linear defects, as opposed to a structureless planar defect which is inherent in current models. This is the basis on which prevailing models for the structure and energy of interfaces are grounded, and we extend this definition to phonon-interface scattering. We apply the analytical expression derived here to phonon-GB strain field scattering from a symmetric tilt grain boundary. It is shown that phonon diffraction conditions arise from the periodic nature of these defect arrays as can be expected from the wave-like nature of phonons. Furthermore, for diffuse heat conduction, a dimensionality crossover is observed in the frequency (ω) dependence of the scattering rate which arrises from phase space considerations. This crossover in defect dimensionality provides a mechanistic understanding for ω-dependence in phonon-interface scattering, transmissivity, specularity, and the T2 behavior in the low temperature lattice thermal conductivity of polycrystalline and nanocrystalline materials.
G.J.S. and R.H. acknowledge EFRC Solid-State Solar-Thermal Energy Conversion Center (S3TEC) Grant DE-SC0001299.- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- 2018
- Bibcode:
- 2018APS..MARB21007H