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Acta Materialia 89 (2015) 344-351

Atomic structure and chemistry of dislocation cores at low-angle tilt grain boundary in SrTiO3 bicrystals

by Hongchu Du, Chun-Lin Jia, Lothar Houben, Veronika Metlenko, Roger A De Souza, Rainer Waser, and Joachim Mayer

Dislocations in perovskite oxides have been found to have important impacts on their electronic and ionic transportation properties, which are believed to be related to the structure and chemistry of dislocation cores. For dislocation cores at a 6° low-angle [001] tilt grain boundary in SrTiO_{3}, an embedded TiO_{x} rocksalt-like structure has been suggested, consistent with a deficiency of Sr. However, direct evidence supporting these suggestions has not been obtained up to now.


In the present study, the atomic structure and chemistry of edge dislocation cores at a low-angle [001] symmetric tilt-boundary in SrTiO_{3} bicrystals is revealed by imaging techniques of high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and electron energy loss spectroscopy (EELS) making use of the ER-C's PICO microscope operated at 80 kV. The experimental results demonstrate direct evidence for a local coordination of edge-sharing TiO_{6} octahedra at the dislocation cores, which can be understood as the result of strain. The local coordination of edge-sharing TiO_{6} octahedra is associated with the face-centered cubic (FCC) NaCl-type TiO phase. The present study therefore provides a solid structural and chemical basis for understanding the properties of dislocations.

Further reading:

Hongchu Du, Chun-Lin Jia, Lothar Houben, Veronika Metlenko, Roger A De Souza, Rainer Waser, and Joachim Mayer: Atomic structure and chemistry of dislocation cores at low-angle tilt grain boundary in SrTiO3 bicrystals, Acta Materialia 89 (2015) 344-351.
   
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