The 18O diffusion coefficients were measured in the oxide by means of secondary ion mass spectrometry. The results were interpreted as indicating an extrinsic behaviour. The magnitudes of the lattice diffusion coefficients for dopants with a higher valence than Zn, were greater than those for lower-valence dopants such as Li. By using data for greater depths, the grain boundary diffusivity of oxide ions was also evaluated. It was noted that, although the lattice diffusion coefficients varied by 2 orders of magnitude, the product of grain boundary width and grain boundary diffusion coefficient was less sensitive to the type of dopant.

Oxygen Diffusion in Single- and Poly-Crystalline Zinc Oxides. Haneda, H., Sakaguchi, I., Watanabe, A., Ishigaki, T., Tanaka, J.: Journal of Electroceramics, 1999, 4, 41-8