Browsing > By author > Brodmann Mathieu

Ferroelectric ceramics are widely used within actuators, sensors, transistors, and solar cells due to their coupled thermo-electro-mechanical properties. Despite their widespread use, the domain nucleation and switching mechanisms within ferroelectric ceramics are not well understood due to the complexities in characterizing a polycrystalline microstructure containing intragranular nanodomains and defects such as pores and precipitates. Domain nucleation and switching mechanisms are hypothetically influenced by both structural features—including the grain orientation, misorientation to neighboring grains, proximity to defects, and the initial domain structure, and the loading configuration—including the boundary conditions, stress applied, and the electric field loading rate. To understand such effects, we have developed an in-house electrical testing setup capable of capturing the bulk ferroelectric response. To connect the bulk polarization hysteresis to the micro-scale evolution of domains, the microstructure is characterized both before and after electrical loading using electron backscatter diffraction (EBSD). We have developed a novel reindexing approach that accurately identifies domain variants in tetragonal ferroelectrics. Minute intensity differences produced by dynamical diffraction within a non-centrosymmetric crystal structure cannot be identified through traditional Hough-indexing, but they can be identified through weighted correlations to simulated patterns of all pseudosymmetric variants. This novel method provides a wealth of microstructural data, giving insight into condition-specific ferroelectric switching mechanisms. The new mechanistic understanding that our research provides will guide microstructural design strategies to yield a target bulk ferroelectric response.