Direct imaging, by means of stroboscopic X-ray topography, of phonon-induced dislocation vibrations was reported. The X-ray images of crystals excited by 0.58GHz surface acoustic waves revealed individual acoustic wave-fronts as well as their distortion upon crossing the dislocation line. The observed contrast was well explained by considering the dynamic deformation field of a vibrating dislocation. A comparison of simulated deformation maps and X-ray images permitted the determination of the local velocities of vibrating dislocations, and their viscosity coefficients. Unexpectedly high velocities (not far below the speed of sound) were found, as well as extremely low viscosity coefficients which were 2 to 3 orders of magnitude lower than those previously measured in ductile materials.

Stroboscopic X-Ray Imaging of Vibrating Dislocations Excited by 0.58GHz Phonons. D.Shilo, E.Zolotoyabko: Physical Review Letters, 2003, 91[11], 115506 (3pp)