Investigation of size effects in ferroic materials using phase field simulations

点击翻译按钮获取中文摘要

The project investigates size effects in ferroic materials by phase filed simulations. In the first funding period the research focus was onferroelectric materials. The size effects in thin films and at crack tips were investigated numerically. In thin films the effect of the film thickness on the poling behaviour was shown. In thin films the lattice mismatch of the electrode material leads to mechanical load in the active material. This influence of the electrode material was demonstrated. In addition, a three dimensional model, which is basedon an invariant formulation, was developed an implemented within the finite element method. The simulations of thin films of ferroelectric materials will be continued. Especially the effect of dislocations at the interface of the electrode and active material will be studied. Furthermore, the methods will be extended to ferromagnetic materials in the next funding period. The investigations focus on the coupling of the ferroelectric and ferromagnetic phase via mechanical deformations at the material interface. To this end a suitable finite element formulation has to be developed that accounts for both ferroic phases in a common simulation. It is anticipated that complex interacting domain structures appear in the ferroelectric as well as in the ferromagnetic phase. The interaction will be studied numerically with regard to size effects.