The diffusion of O in nanocrystalline undoped monoclinic samples was studied by using 18O tracers and secondary ion mass spectrometric profiling. Samples with a density of 97 to 99%, and average crystallite sizes of 80 and 300nm were prepared from Zr by direct-current sputtering, crystallite condensation in an inert-gas atmosphere, oxidation, in situ consolidation of nanocrystalline oxide powder, and pressureless sintering at 950 or 1050C in vacuum. The volume and interface diffusivities were determined from the depth profiles in the type-B regime. The activation energies for bulk and boundary diffusion were equal to 2.29 and 1.95eV, respectively. These values were considerably higher than those found for Ca- or Y-stabilized zirconia. No effect of crystallite size was detected.

18O Diffusion in Nanocrystalline ZrO2. U.Brossmann, U.Sodervall, R.Wurschum, H.E.Schaefer: Nanostructured Materials, 1999, 12[5-8], 871-4

Figure 42

Bulk Diffusivity of 18O in Nanocrystalline Monoclinic ZrO2