Regensburg 2010 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 10: Dielectric surfaces and interfaces

DF 10.3: Vortrag

Mittwoch, 24. März 2010, 15:05–15:25, H11

Theoretical atomic-scale study of the interaction of grain boundaries with domain walls in ferroelectric PbTiO₃ — •Pavel Marton and Christian Elsässer — Fraunhofer-Institut für Werkstoffmechanik IWM, Wöhlerstraße 11, 79108 Freiburg, Germany

Perovskite-type ferroelectric ceramics for actuators and sensors like PbTiO₃ or Pb(Zr,Ti)O₃ have dense polycrystalline microstructures. Within micrometer-sized grains, even smaller ferroelectric domain structures are found. Both domain walls (DW) and grain boundaries (GB) play an important role in the macroscopic material performance.

An objective of this work is an investigation of fundamental properties of interactions of DW with GB in tetragonal PbTiO₃. Atomic-scale experimental observations of GB in perovskites are rare and difficult to obtain. Therefore, the interfaces studied theoretically in this work were motivated by experimental observations of Sigma=3 [1] and Sigma=5 [2] symmetrical tilt GB in SrTiO₃. We focus on interfaces, which are both GB and ferroelectric DW. Atomic structures were obtained using atomistic shell-model simulations and ab-initio density functional theory (DFT) calculations. For the chosen GB, DFT calculations provide detailed insight into atomic arrangements, energetic stabilities and electronic states of the interfaces. We discuss properties of GB with DW in dependence on their type, and we compare them with properties of interfaces in cubic SrTiO₃ [3].

[1] S. Hutt et al., J. Phys.: Condens. Matter 13 3949 (2001).

[2] M. Imaeda et al., Phys. Rev. B 78 245320 (2008).

[3] N. Benedek et al., Phys. Rev. B 78, 064110 (2008).