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MM: Fachverband Metall- und Materialphysik

MM 2: Topical Session TEM I

MM 2.1: Topical Talk

Monday, March 14, 2011, 11:00–11:30, IFW A

Study at picometres precision of structure and properties of oxide ferroelectrics — •Chun-Lin Jia — Institute of Solid State Research and Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany

Epitaxial thin films of ferroelectric oxides have attracted increasingly intensive research both for fundamental and application issues. The physical properties of these film systems depend strongly on the particular microstructure and configuration of lattice defects.

By means of a spherical aberration corrector in a transmission electron microscope the value of the spherical aberration Cs can be tuned to negative values resulting in a novel imaging technique: The negative Cs imaging (NCSI) technique. The images obtained with the NCSI technique are superior to positive Cs images in the magnitude of the contrast and the image intensity of atom columns. The image signal obtained with the NCSI technique is significantly more robust against noise, resulting in measurement of atomic positions with a precision of a few picometres.

In this talk, we present the results of a study using NCSI technique of the epitaxial thin-film system of PbZr0.2Ti0.8O3. The positions of all the atomic species are measured, unit cell by unit cell, with a precision of a few picometres. On this basis the relative ion displacements in the individual unit cells are calculated. These displacements depict the details of electric dipole moments in domains, at domain walls, as well as at defect area.