Surface enhancement of oxygen exchange and diffusion in the ionic conductor La2Mo2O9

Isotopic surface oxygen exchange and its subsequent diffusion have been measured using secondary ion mass spectrometry in the fast ionic conductor La2Mo2O9. A silver coating was applied to the sample surface to enhance the surface exchange process for dry oxygen. Contrary to previous studies performed using a wet atmosphere, no grain boundary diffusion tail was observed under these optimized dry exchange conditions. The activation energy for oxygen diffusion was found to be 0.66(± 0.09) eV at high temperature (> 570 °C), and 1.25(± 0.01) eV at low temperature (< 570 °C). Time-of-Flight secondary ion mass spectrometry was employed to investigate the correlation between the silver coating and the 18O concentration on the sample surface. A close correlation between the presence of silver and oxygen incorporation on the surface was observed.