Nitrogen diffusion in nitrogen-doped yttria stabilised zirconia

Abstract

Nitrogen self-diffusion was measured in single crystalline nitrogen-doped yttria-stabilised zirconia (YZrON) containing 10 mol% yttrium oxide. Samples containing two different nitrogen contents (5 and 6 mol% N on the anion sublattice) were investigated as a function of temperature (650–1000 K) using implanted 15N as a stable tracer. For a given temperature, the nitrogen diffusivity was nearly independent of the nitrogen content in the nitrogen-doped yttria-stabilised zirconia, which can be only partially understood using defect chemistry. The activation enthalpy of nitrogen diffusion was between 2 and 2.5 eV with a preexponential factor of the order of 100 cm2 s−1, which corresponds to a migration entropy of 5 kB. The surface exchange reaction between nitrogen and the oxonitride surface was investigated at 1073 K using 200 mbar gaseous 15N2 and was found to be slow but considerable. Decreasing the oxygen content in the gas phase can enhance the nitrogen incorporation into the oxonitrides.Instituto de Física La Plat

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