ABSTRACT
This chapter aims to derive expressions for both phonon relaxation time and kernel of the collision operator by considering a few examples of phonon scattering processes in non-metallic crystals. These are: boundary scattering, scattering with static imperfections, three-phonon scattering, four-phonon scattering, phonon-electron and phonon-hole scatterings in doped semiconductors, phonon scattering by magnetic impurities and phonon scattering by tunnelling states. The chapter presents the theory of phonon-photon interaction related to the processes of infrared absorption and Raman scattering in crystals. P. G. Klemens has studied the scattering of phonons by static imperfections. By using perturbation theory he has derived expressions for the single-mode phonon relaxation time due to scattering by a substitutional atom of different mass, by an atom of different binding force, by dislocations, and by grain boundaries. Time-dependent perturbation theory can be applied to study scattering of phonons by other kinds of crystal imperfections such dislocations, stacking faults, and grain boundaries.
