A study was performed that directly compared the experimental and theoretical diffusion pathways of oxygen in this double cobaltite compound. Model-free experimental nuclear density maps were obtained from the maximum entropy method combined with Rietveld refinement against high-resolution neutron diffraction data collected at 1173K. They were then compared to theoretical maps resulting from classical molecular dynamics calculations. The analysis of 3D maps of atomic densities permitted unambiguous identification of the pathways and the mechanisms involved in the oxide ion diffusion. It was shown that oxygen diffusion occurred along a complex trajectory between Nd- and Co-containing a,b planes. The study also revealed that Ba-containing planes acted as a barrier to oxygen diffusion. The diffusion mechanism was also supported by an oxygen site occupancy analysis that confirmed an increase in oxygen vacancies in the cobalt-planes upon heating.

Oxygen Diffusion Mechanism in the Mixed Ion-Electron Conductor NdBaCo2O5+x. Hu, Y, Hernandez, O., Broux, T., Bahoutm, M., Hermet, J., Ottochian, A., Ritter, C., Geneste, G., Dezanneau, G.: Journal of Materials Chemistry., 2012, 22, 18744-7