Measurement of oxygen transport in La0.8Sr0.2MnO3 perovskite grains

In this work values for the diffusion coefficient, D*, and surface exchange coefficient, k*, have been obtained from individual La0.8Sr0.2MnO3 perovskite grains. Oxygen tracer diffusion profiles were created via the well established isotope exchange techniques. The tracer diffusion profiles were then measured using a FIB-SIMS workstation. Several measurements were taken over randomly selected grains including un-faceted and faceted grains. The values for D* and k* obtained compared very well with previous measurements made on bulk La0.8Sr0.2MnO3 samples i.e. over many grains. The results therefore indicate that D* and k* are independent of orientation. Furthermore the diffusion profiles indicated that only one single grain had been SIMS depth profiled and did not cross a grain boundary. Also by analysing in the centre of large grains, and not analysing up to the edge of the grains, no grain boundary diffusion was observed. Finally, the work also confirms that previous measurements of k* on this material have been correctly measured and not under estimated due to experimental errors.