Enhanced oxygen diffusivity in interfaces of nanocrystalline ZrO 2 ⋅Y 2 O 3

First measurements of oxygen grain boundary diffusion coefficients in nanocrystalline yttria-doped ZrO 2 (n-ZrO 2 ⋅6.9 mol % Y 2 O 3 ) are presented. The 18 O diffusion profiles measured by secondary ion mass spectroscopy are much deeper in the nanocrystalline specimens than in single crystals. An oxygen diffusivity, D B , in the grain boundaries can be deduced, which is ≈3 orders of magnitude higher than in single crystals. From the present data the temperature variation of the oxygen grain boundary diffusivity, D B = 2.0 × 10 −5 exp (−0.91 eV/ k B T ) m 2 /s, and the oxygen surface exchange coefficient, k = 1.4 × 10 −2 exp (−1.13 eV/ k B T ) m/s, are derived.