Sub-structure characterization of experimentally and naturally deformed ice using cryo-EBSD

• Published in: Journal of Microscopy
• Main Authors: Piazolo, S., Montagnat, Maurine, Blackford, J. R.
• Other Authors: Department of Geology and Geochemistry Stockholm, Stockholm University, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), School of Engineering and Electronics, University of Edinburgh (Edin.), Centre for Materials Science and Engineering, European Science Foundation (ESF), EUROCORES Programme EuroMinScl, FP6
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: Cryo-EBSD; crystallographic orientation; deformation; ice; sub-structure; tilt walls; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Antarc*; Antarctica; ice core
• Online Access: https://insu.hal.science/insu-00381041; https://doi.org/10.1111/j.1365-2818.2008.02014.x

International audience In this work, we present first results of high-resolution EBSD for ice with a spatial resolution down to 0.25 μm. The study highlights the potential of EBSD to significantly increase our understanding of deformation and annealing processes associated with the build-up of internal stresses due to strain incompatibility between grains. Two polycrystalline samples were analyzed: a natural sample of polar ice from the Vostok ice core (Antarctica) and an experimentally deformed sample of laboratory grown columnar ice. In summary, we observe the following: (1) inhomogeneous deformation through the grains is translated into lattice distortions that are concentrated mainly at grain boundaries and triple junctions (natural and experimental sample), (2) these distortions may be continuous (natural and experimental sample) or may form distinct tilt boundaries and sub-grains of 10–50 μm size (experimental sample). These form mainly by rearrangement of basal edge dislocations into low-energy configurations (i.e. tilt boundaries) in various prism planes. Continuous lattice distortions originate from screw or mixed edge and screw dislocations lying in the basal plane.