Microstructural interaction and switching in ferroelectrics
The main goal of this project is the multi-scale modelling of rate-dependent microstructure evolution in ferroelectrics. Two different models will be developed on the level of single-crystals and further extended to the level of oligo-crystals. As a general modelling framework, the previously established laminate-based approach will be employed. In particular, this formulation will be extended to include the effect of interfaces. Within the context of mixture theory, the laminate-related volume fractions represent the microstructure in this approach. Alternatively, the ferroelectric microstructure will be modelled with the help of level-set methods. In the context of the finite-element method, this enables the simulation of spatially resolved microstructures. Both the volume-fraction- and level-set-based models will be calibrated using experimental data on single-crystals. Related finite element simulations, which can consider the positions and orientations of individual grains, enable the simulation of oligo-crystals within both modelling frameworks. The level-set approach naturally includes more information than the volume-fraction-based model, since the level-set formulation spatially resolves the microstructure. This is at a higher computational cost, however, so that a comparison of both models contributes to the evaluation of the quality, efficiency and applicability of the laminate-based model. Both models contribute to a better understanding of the local microstructure evolution in technologically meaningful ferroelectrics. This enables an improved prediction of, e.g., lifetime properties of typical ferroelectric actuators and sensors.