Measurement of defect-mediated oxygen self-diffusion in metal oxides

Solid-state diffusion of native defects in some metal oxides takes place via highly mobile intermediate species that periodically exchange with lattice atoms. A mathematical model has been formulated to determine the key diffusion parameters from mesoscopic gas-solid diffusion measurements in the short-time limit. The model provides a straightforward analytical means to utilize standard isotope gas-solid exchange experiments to obtain parameters connected to diffusion length and net rate of defect formation at the surface. Application of the method to experimental data for oxygen self-diffusion in titanium dioxide suggests that under conditions where gas-solid exchange takes place through an especially clean surface, a fast-moving species mediates oxygen self-diffusion.