Probing Oxide Ion Conduction in La0.9−x AxSr0.1Al0.9Mg0.1O3−δ (A = Ba, Sm) Electrolyte Material with Pt and Ag as Electrode

Abstract

The present work is based on a comparative study of electrode-electrolyte Ag/M/Ag with a Pt/M/Pt configuration, where M = (La0.9−x (A)x) Sr0.1 Al0.9 Mg0.1 O3−δ (A = Ba, Sm) for x = 0.00 and 0.03 (classified as B0, B3 and S3) behavior for electrochemical devices (individually in solid oxide fuel cells) through impedance studies. A differential impedance study approach is utilized to boost the analysis of impedance data. For all compositions, it is found that the conductivity (σPt/M/Pt) of the Pt/M/Pt configuration is greater than the conductivity (σAg/M/Ag) of the Ag/M/Ag configuration at 500°C. In contrast to the Ag/M/Ag configuration (M = B0, B3), Ghosh scaling for the Pt/M/Pt configuration is determined to be valid; however, Ghosh scaling is invalid for the Ag/M/Ag or Pt/M/Pt (M = S3) configuration. A decrease in the power exponent for the Ag/B0/Ag configuration is observed as compared to the increase seen in Pt/B0/Pt around the zone boundary transition. This rate-limiting step is quantitatively analyzed in terms of resistance obtained through bound constant phase element behavior, which is further analyzed in terms of the value of fractal exponent (K). For the Pt/B0/Pt configuration, a continuous increase of fractal exponent (K) with temperature is observed, whereas a transition is observed for the Ag/B0/Ag configuration. In Pt/B3/Pt and Ag/B3/Ag, similar behavior is observed. There is a correlation between the oxygen vacancy compensation and the small variations in the K values from B0 to S3. © The Minerals, Metals & Materials Society 2025.