2017 Basic Science Division Robert B. Sosman Lecture
Basic Science Division Robert B. Sosman Lecture
1-2 p.m., October 11, Room 315
Michael J. Hoffmann, Karlsruhe Institute of Technology (KIT), Germany
Grain Growth in Perovskite-Based Ceramics
Perovskites are functional materials widely used as dielectrics, sensors, actuators, transducers, etc. The properties can be tuned in a wide range depending on composition and microstructure. To understand the microstructural evolution of perovskites, strontium titanate was used as model system. It shows an unexpected growth transition with decreasing growth rates for rising temperatures. The transition is strongly correlated to abnormal grain growth that can be often observed in perovskite ceramics. The growth effects are investigated with different model experiments which focus on the impact of the relative grain boundary energy and mobility. A unified theory for grain growth transitions is presented considering microstructural appearance, abnormal grain growth and drag effects. A coexistence of different grain boundary characteristics featuring different grain boundary mobilities is proposed. Finally it will be discussed which types of experiments and simulations have to be considered to fully understand and predict the microstructural evolution of a ceramic.