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The Core Structure of Basal Dislocations in Deformed Sapphire (α-Al2O3)

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Science  26 Nov 2010:
Vol. 330, Issue 6008, pp. 1227-1231
DOI: 10.1126/science.1192319

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Deformed Sapphire

The structure of sapphire consists of alternating sheets of oxygen ions and puckered aluminum ions. Although brittle at low temperature, the material can deform at high temperatures through structural dislocations. Heuer et al. (p. 1227) used a high-resolution transmission electron microscope and the negative spherical aberration imaging technique to distinguish between the columns of Al and O ions. Upon deformation, the Al ions moved into both tetrahedrally and octahedrally coordinated sites, and while the dislocation cores spread out, they remained uncharged and stoichiometric. The results may connect to the deformation behavior of other nonmetallic solids.

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