Biography
Biography: Manfred Martin
Abstract
Oxygen diffusion in complex oxide materials is of great importance for applications, e.g. in fuel cells (oxygen ion conductivity) or oxygen permeation membranes (ambipolar diffusion of oxygen). For heavily doped oxides, such as doped zirconia, ceria or lanthanum gallate, we give a qualitative and quantitative explanation of the observed maximum of the conductivity as a function of the dopant fraction by combining DFT calculations of energies and entropies with Kinetic Monte Simulations of the oxygen ion conductivity.
Concerning cation diffusion in complex oxides we report our recent findings in perovskites, with a special focus on doped lanthanum gallates, barium titanate, and BSCF. Our experimental results indicate that the cation diffusion mechanisms are more complicated than simple vacancy mechanisms. We show that the experimental observations can be explained well by A- and B-site cation vacancies that are strongly bound in defect clusters and perform a highly correlated motion.