Determination of Chemical Diffusion Coefficients of Mixed Ionic‐Electronic Conductors with Arbitrary Electronic Transport Numbers Application of Impedance, Potentiostatic, and Galvanostatic Methods to

摘要: The solution of the diffusion equation for chemical processes in a mixed conductor located between an electronically blocking electrode and ionically asymmetric electrochemical cell (coulometric titration cell) has been extended to materials with arbitrary electronic transport numbers. This allows derivation evaluation formulas impedance spectroscopy as well potentiostatic galvanostatic polarization experiments order determine coefficient mixed-conductivity compounds comparable ionic conductivities. Impedance measurements are applied Ag 1.92 Te function composition at 160°C using I AgI | Pt. may be regarded typical example ionic-electronic numbers needed obtained from separate partial conductivities by applying dc four-point van der Pauw method. Typical values number range 0.8 0.9 160°C. increases slightly increasing silver content sample, around 0.003 cm 2 s -1 . In case experiments, non-Cottrell behavior process is observed. Agreement experimental results three methods remarkably good.