| Summary: | Surface exchange coefficient (<i>k</i>) and bulk diffusion coefficient (<i>D</i>) are important properties to evaluate the performance of mixed ionic-electronic conducting (MIEC) ceramic oxides for use in energy conversion devices, such as solid oxide fuel cells. The values of <i>k</i> and <i>D</i> are usually estimated by a non-linear curve fitting procedure based on electrical conductivity relaxation (ECR) measurement. However, the rate-limiting mechanism (or the availability of <i>k</i> and <i>D</i>) and the experimental imperfections (such as flush delay for gaseous composition change, <i>τ<sub>f</sub></i>) are not reflected explicitly in the time–domain ECR data, and the accuracy of <i>k</i> and <i>D</i> demands a careful sensitivity analysis of the fitting error. Here, the distribution of characteristic times (DCT) converted from time–domain ECR data is proposed to overcome the above challenges. It is demonstrated that, from the DCT spectrum, the rate-limiting mechanism and the effect of <i>τ<sub>f</sub></i> are easily recognized, and the values of <i>k</i>, <i>D</i> and <i>τ<sub>f</sub></i> can be determined conjunctly. A strong robustness of determination of <i>k</i> and <i>D</i> is verified using noise-containing ECR data. The DCT spectrum opens up a way towards visible and credible determination of kinetic parameters of MIEC ceramic oxides.
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