Observation of Etch Channels on the (0001) Plane of Ice Crystal Produced by Nonbasal Glide

A method developed by one of the authors for producing minute etch pits on the (0001) surface of ice crystal in coordination with electron microscope observations was used to reveal the behaviors of dislocations in ice crvstal when it was deformed. Etch channels which run in the crystallographic direction, either <1120> or <1010>, were found. The origins of these etch channels were considered and a mechanism was presented of their formation, constituted of two stages: formation of vacancy trails behind the moving screw or mixed dislocations on glide systems of {1010}<1123>, {1010}<1120> and {1122}<1123> and precipitation of impurities in the vacancy trails. In the case of inclined trails on the glide plane of (1010), deposition of impurities on the (0001) plane was assumed to motivate etching. This mechanism is believed to be plausible by reason of various features of the etch channels.