Experimental Study of Non-Basal Dislocations in Ice Crystals

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Abstract
Structures produced by chemical etching on the basal plane of ice crystals have been studied and are discussed in terms of non-basal glide features. Slip bands, revealed by parallel rows of etch pits, generally result from a rapidly applied stress. Etch channels were observed relatively rarely in these experiments; they can be interpreted as trails of dislocations moving slowly under the action of local stresses, sometimes to stresses produced during the etching process. Features of the channels indicate that the dislocations emerging on the basal plane are screw dislocations; their Burgers vector was considered by previous authors to be in the direction , gliding on {1122}and {101o} slip planes. This assumption is inconsistent with the changes of channel direction we observed, for which the {0111}and {2421}slip planes would have to be considered. As a simpler hypothesis the glide system ⟨0001⟩, {101o} and ⟨0001⟩, {1120}is proposed.