Dresden 2011 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 2: Topical Session TEM I

MM 2.3: Vortrag

Montag, 14. März 2011, 12:00–12:15, IFW A

Direct evidence for cation non-stoichiometry and Cottrell atmospheres around dislocation cores in functional perovskite oxide interfaces — •Miryam Arredondo¹, Quentin Ramasse², Matthew Weyland³, Ionela Vrejoiu¹, Dietrich Hesse¹, Nigel Browning⁵, and Valanoor Nagarajan⁴ — ¹MPI of Microstructure Physics, Halle, Germany — ²LBNL NCEM, Berkeley, CA, USA. — ³MCEM, Monash Uni., Victoria, Australia — ⁴SMSE, UNSW, Australia — ⁵Chem. Eng. & Mater. Sci., UC Davis, USA.

Exploiting the electronic properties of oxides in functional devices requires their deposition on an underlying substrate, often with an unavoidable lattice mismatch. We consider the chemical implications in the accommodation of this mismatch by misfit dislocations, by the characterization of the lattice mismatched system: a PbZr0.52Ti0.48O3 ferroelectric film deposited on a SrRuO3 electrode-buffered SrTiO3 substrate. Cs-corrected Z-contrast imaging and chemical analysis techniques are exploited to yield evidence for cation excess within dislocation cores at the interface. Multislice image simulations reproduces fairly well the observed image contrast. EDX maps reveal Pb and Sr interdifussion and EELS scans at the core reveal that it is oxygen-deficient compared to the defect-free lattice. Geometric phase and theoretical elastic modeling reveal that the local strain around the dislocation core is sufficient to create stress-assisted diffusion of cations. This study provides insights into the link between the local chemistry, physical structure and observed functional behavior in the ferroelectric at the proximity of a dislocation core.