A comparison analysis on electrical conductivity relaxation methods

This study compares the Distribution of Characteristic Times (DCT) and ECRTOOLS for analyzing oxygen transport kinetics in mixed ionic-electronic conductors (MIECs). Experimental validation on dense Sr₂Fe_1.5Mo_0.5O_6−δ(SFM) under stepwise oxygen partial pressure changes demonstrates that ECRTOOLS, relying on three-dimensional Fickian diffusion and single-mechanism assumptions, fails to accurately fit data. In contrast, DCT converts time-domain relaxation into frequency-domain spectra, resolving multi-mechanistic dynamics via characteristic time distributions. DCT distinguishes surface exchange control (single peak), bulk diffusion control (τ_P1/τ_P2 = 9), and mixed control (τ_P1/τ_P2 > 9), achieving lower residuals than ECRTOOLS. While ECRTOOLS yields unphysical parameters violating Biot number consistency, DCT captures synergistic oxygen vacancy-surface exchange interactions. Challenges persist in interpreting non-ideal spectral artifacts and linking peaks to microstructural properties. This work establishes DCT as a superior tool for probing complex transport mechanisms, advancing the design of electrochemical devices like solid oxide fuel cells.^{[email protected]}