Ferroelasticity and Hysteresis in Mixed Ionic Electronic Conducting Perovskites

In this proposal we aim to build on our recent discovery of ferroelasticity and hysteresis in mixed ionic-electronic conducting (MIEC) lanthanum cobaltite (LaCoO3) perovskites and generate a fundamental understanding of the origin of this behavior. The effect of the external loading on the elastic hysteresis and ferroelastic behavior of perovskites will be characterized by the compression tests. Unique in-situ techniques in electron microscopy and X-ray diffraction will be employed to analyze the lattice distortions and defect structures, domain and domain wall microstructures, and vacancy ordering/clustering that occurs during the paraelastic to ferroelastic phase transition in lanthanum cobaltite perovskites as a function of pressure, temperature and composition. As a basic understanding of the ferroelastic properties of these materials is not currently available, such research is essential to understand the origin of elastic instabilities and the mechanical properties of MIEC materials used for high-temperature syngas reactors, oxygen sensors, catalysts, and solid oxide fuel cells (SOFCs).