Controlling core-shell structures in (Na1/2Bi1/2)TiO3 based ceramics and investigating their impact on electrical properties

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Electroceramics are usually optimized by doping them with foreign ions to modify, for example, electrical conductivity, magnetic properties, and ferroelectric properties. In research, however, we often come up against the limits of this strategy. Composite materials often prove to be another way to create materials with new or improved properties. However, this is very complicated for ceramics, which usually have to be sintered at high temperatures. Interestingly, materials based on (Na1/2Bi1/2)TiO3 can form core-shell composites solely through regular solid-state synthesis. The formation of the composite correlates with a drastic change in the ferroelectric properties. The material behaves more like an anti-ferroelectric. Such a ceramic would have enormous advantages when used as a capacitor material for storing high electrical energy with high power density at the same time. In the area of the use of electrical energy, there is the challenge of meeting the new requirements with regard to efficient energy transmission. Energy from renewable sources, in particular, can be exposed to high fluctuations, and this makes it difficult to provide all of the energy for use. Efficient, high-power, high-energy capacitors are an important component in achieving the goal. This is why capacitors based on the aforementioned electroceramics could be a solution here. How the material has to be modified in order to obtain the desired properties is still completely unclear. Although it is known that variations in the defect chemistry lead to major changes, we are still far away from the control of the properties. Therefore, an investigation of the defect chemistry and the origin of the electrical behavior is of great importance. We want to address that with the present project.