Phonon scattering by dislocations in LiF crystals

Abstract

A theory is presented of the interaction between thermal phonons and a vibrating dislocation. An expression for the relaxation time of the phonon is obtained which is valid in an anisotropic medium. The relaxation time depends on the strength of the imaginary part of the effective mass of the vibrating dislocation. We have calculated numerically this factor for LiF and have found the mode dependence to be very strong. The slow transverse-mode component is about ten times larger than the other mode components. Hence, the slow transverse mode is scattered more strongly than other modes by vibrating dislocations in LiF. Agreement with experimental data is obtained.