Imaging dislocations in ice
Article first published online: 18 AUG 2003
Copyright © 2003 Wiley-Liss, Inc.
Microscopy Research and Technique
Special Issue: Advanced Techniques for the Characterization of Ice and Snow
Volume 62, Issue 1, pages 70–82, 1 September 2003
How to Cite
Baker, I. (2003), Imaging dislocations in ice. Microsc. Res. Tech., 62: 70–82. doi: 10.1002/jemt.10382
- Issue published online: 18 AUG 2003
- Article first published online: 18 AUG 2003
- Manuscript Received: 28 JAN 2003
- Manuscript Accepted: 28 JAN 2003
- Army Research Office
- U.S. National Science Foundation. Grant Numbers: OPP-9980379, OPP-0221120, DAAD 19-00-1-0444
- X-ray topography;
Three techniques have been used to study dislocations in ice: etch pitting-replication, transmission electron microscopy, and X-ray topography (XT). It is shown that, because ice is a weak absorber of X-rays and can be produced with a low dislocation density, allowing relatively thick specimens to be studied, the most useful technique is XT. The observations that have been made with conventional XT are briefly outlined. However, the introduction of high-intensity synchrotron radiation, with its concomitant short exposure times, showed that images obtained through conventional XT observations were of dislocations that had undergone recovery. The important dynamic observations and measurements that have been made using synchrotron X-ray topography are presented. Dynamic synchrotron X-ray topography observations of ice single crystals undergoing deformation in situ have shown that slip mainly occurs by the movement of screw and 60° ⅓〈1120〉 dislocations on the basal plane, although non-basal slip by edge dislocations can also occur. The operation of Frank-Read and other dislocation multiplication sources have been clearly demonstrated and dislocation velocities have been measured. In contrast, in polycrystals, dislocation generation occurred at grain boundaries where there are stress concentrations before lattice dislocation generation mechanisms operate. Faulted dislocation loops have been determined to be mainly interstitial in both polycrystals and single crystals. Microsc. Res. Tech. 62:70–82, 2003. © 2003 Wiley-Liss, Inc.