Oxygen (non-stoichiometry) re-equilibration kinetics were examined, via a conductivity relaxation method, on 1m/o donor La-doped BaTiO3 (nominal composition, Ba0.99La0.01Ti0.9975O3) against O partial pressure in the range of –16 < log[PO2/atm] less than 0 at 1200C. The kinetics were found to be onefold with a single relaxation time or twofold with 2 different relaxation times depending on O activity. It was attributed to the relative contributions depending on the O activity of fast relaxation of the O sub-lattice and sluggish relaxation of the cation sub-lattices: their revelations were determined by the ratio of O vacancy to cation vacancy concentrations and their relaxation times. Their chemical diffusion coefficients were deduced, from the relaxation times, to be DO = 10-4 to 10-6cm2/s and DTi = 10-15 to 10-11cm2/s; depending upon O the activity. These values were in good agreement with the reported values. Defect diffusivities were subsequently determined by using the thermodynamic factors of component O and Ti, which were evaluated from the equilibrium conductivity isotherm, as being 1.4 x 10-5 and 1.4 x 10-15cm2/s, respectively.

Two-Fold Diffusion Kinetics of Oxygen Re-Equilibration in Donor-Doped BaTiO3. H.I.Yoo, C.E.Lee: Journal of the American Ceramic Society, 2005, 88[3], 617