Basal glide of dislocations in ice observed by synchrotron radiation topography

Abstract

In-situ observation of basal glide of dislocations in ice has been carried out using synchrotron radiation topography (SRT) between −0.2 and −18.4°C under uniaxial compressions. The maximum shear stress on the basal plane was chosen to be 0.060 MPa in order to observe the glide motion of dislocations under low stresses. The radii of curvature of dislocation bends in the steady state are measured on a scale of SRT subject to the low-stress conditions. From the radius of curvature and dislocation velocity, the concentration of thermal kinks on the dislocation and the kink velocity are separately estimated. The migration free energy estimated from the kink velocity agrees well with the free energy of the Debye relaxation time that is generally accepted.