Isotope exchange with C~18O_2 followed by depth profiling analysis was used to study surface exchange and bulk diffusion of oxygen in single crystal yttria-stabilized zirconia in the temprature range 250 deg C-350 deg C. The depth profiles, which were obtained using 18O(#rho#,#alpha#) 15N nuclear reaction analysis and secondary ion mass specrometry, reveal both the bulk oxygen difusion coefficients and surface exchange coefficients. Bulk oxygen idffusion coefifcients are consistent with an extrapolation to lower temperature of previously published results with an activation energy of 114KJ/mol. The surface exchange rates, however, depend strongly on the gas exchange species. Much higher exchange rates are observed with C~18O_2 than with 18O_2 with a measured activatio energy of 152KJ/mol(1.6eV). This faster surface exchange rate enabled measurable 18O tracer profiles to be genrated at lower temperatures than previously reported, further ocntributing to the udnerstanding of YSZ material properties and brining to light a possible order/disorder transition similar to that previously obsreved at 650 deg C.
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