Dresden 2009 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 16: Thin Films and Nanostructures III

DF 16.1: Invited Talk

Thursday, March 26, 2009, 14:30–15:05, WIL B321

Simulation of Defects and Domain Structures in Ferroelectrics — •Ralf Müller — Department of Civil Engineering and Geodesy, Solid Mechanics, TU Darmstadt, Hochschulstr. 1, 64289 Darmstadt, Germany

The macroscopic material properties of ferroelectric materials strongly depend on their complex microstructure, which includes length scales from the atomistic level up to the grain size level. Crucial for the understanding of fatigue, degradation and aging phenomena is the interaction of domain walls and domain structures with various defects in the material. In order to analyse these interactions a thermodynamically consistent continuum mechanical approach is taken. Domain walls are modelled as sharp interfaces or are simulated by a phase field approach. The phase field approach can be understood as a regularization of the sharp interface model. Both models are implemented into a special finite element method. Techniques to incorporate localized defects in the continuum are discussed, by a comparative study between atomistic and continuum mechanical simulations. Additionally, the interaction between defects can be studied using thermodynamic arguments.

Pinning phenomena of domain walls at electrode and point defects are shown. Macroscopic material properties are derived from simulations with evolving microstructures by homogenization procedures. The simulated material behavior is compared to some of the few multi-axial experiments available in the literature.