18O diffusion in nanocrystalline ZrO2

The diffusion of oxygen in nanocrystalline, undoped monoclinic ZrO2 was studied using O-18 tracer and SIMS profiling. Samples with a mass density of 97 to 99 % and average crystallite sizes of 80 nm and 300 nm were prepared from Zr-metal by DC sputtering, crystallite condensation in an inert-gas atmosphere, oxidation, in-situ. consolidation of the n-ZrO2 powder and subsequent pressureless sintering at 950 or 1050 degrees C in vacuum. Both volume (V) and interface (B) diffusivities were determined from the depth profiles in the type B regime. The activation energies Q(V) = 2.29 eV and Q(B) = 1.95 eV are considerably higher than the values found in Ca- or Y-stabilized ZrO2. No influence of the crystallize size was observed. (C) 1999 Acta Metallurgica Inc.