Calculation of Pressure Dependence of Dislocation Damping Constant in Crystals

The pressure dependence of the damping constant for a moving dislocation has been calculated and evaluated with the intension of being compared with our results of high pressure experiments. The calculations were made on the basis of the mechanisms of phonon scattering (Leibfried, Klemens, and Brailsford), thermoelastic effect (Eshelby), phonon viscosity (Mason), and fluttering effect (Ninomiya). Pressure derivatives of various quantities appearing in the formulations of these mechanisms were firstly calculated, and then the pressure dependence of the damping constant was evaluated. The higher order elasticity theory could conveniently be used in these calculations. The numerical evaluations were made for the cases of LiF, NaCl, and Al crystals. The experimental second- and third-order elastic constants and the theoretical fourth-order elastic constants were adopted in these evaluations.