Oxygen Diffusion in Single‐Crystal Tetragonal Zirconia

Abstract

The gas-solid isotope exchange method using H2O-18 with the continuously recording gravimetric technique was employed for the measurement of the oxygen tracer diffusion coefficient in single-crystal zirconia. In the temperature range investigated (1300-1600-degrees-C) the tetragonal form of the oxide is stable. Both helium and hydrogen atmospheres were used, the latter to determine the effect of hydrogen on oxygen mobility in the solid. Oxygen diffusion was found to be strongly dependent on trivalent impurities in the oxide. The oxygen vacancy diffusivity was determined from tracer diffusivity measurements in specimens of different impurity levels. Chemical diffusion coefficients were also determined from the tracer diffusivities and compared with values obtained from corrosion rate data.