Kinetics of high-temperature oxide ion and proton conductors

High-temperature oxide ion and proton conductors play important roles in the development of technologies related to efficient and environment-friendly energy production e.g. as electrolytes, electrodes or as membranes for oxygen or hydrogen separation. Th e overall yield in these processes is determined either by surface reactions, by transport processes in the bulk of the oxides or by a combination of these. While bulk transport kinetics in solid-state chemistry is understood to an advanced degree, the co nceptional knowledge on surface kinetics and the relation between surface and bulk parameters is quite poor. The proposed research aims at contributing to bridge the gap between the level of understanding of surface and bulk kinetics. Surface and bulk ki netics will be characterized by several transient techniques. The use of isotopes will be central in the project. A novel technique where the use of isotopes in combination with mass spectrometry aims at determining the rate of surface dissociation, the s urface exchange coefficient and the bulk diffusion coefficient is central. The project will utilize isotope annealing in combination with SIMS-profiling and will, as such, strengthen the implementation of SIMS to research within high-temperature solid-sta te chemistry in Norway. In addition surface and bulk kinetics will be studied by transient thermogravimetry and transient conductivaity measurements. Surface characterization will, in general, be important and a large array of microscopy and spectroscopy techniques will be applied. Overall, this project covers broader aspects than research confined to either surface or bulk kinetics. This approach is novel and, moreover, essential to succeed in reaching an improved understanding of the overall process. S uch fundamental insight will serve as the bases for development of new and better materials for existing industrial processes, as well as for the design of new technologies.