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Electrode Kinetics of Porous La0.5Sr0.5Co0.8Ga0.2O3-δ

Published online by Cambridge University Press:  10 February 2011

Yuemei L. Yang  and
Allan J. Jacobson
Yuemei L. Yang
Affiliation:
Department of Chemistry and Materials Research Science and Engineering CenterUniversity of Houston, Houston, TX 77204-5641
Allan J. Jacobson
Affiliation:
Department of Chemistry and Materials Research Science and Engineering CenterUniversity of Houston, Houston, TX 77204-5641
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Abstract

LSCGO (La0.5Sr0.5Co0.2Ga0.2O3−δ) was selected and synthesized as a cathode material for gallate-based solid oxide fuel cells (SOFC). In the present paper, the electrode polarization behavior of LSCGO was studied under various pO2 and temperature conditions by a two-probe ac impedance method. A symmetric electrochemical cell: pO2, LSCGOILSGMOILSCGO, pO2, where the composition of the electrolyte LSGMO is La0.8Sr0.2Ga0.85Mg0.15O3−δ, was used in the study. Below 600°C, only semicircles due to bulk and grain boundary contributions were observed. In temperature range 700-800°C, however, a depressed and asymmetric semicircle was found in the low frequency regime (1 mHz to 1000 Hz). This low frequency feature in the impedance spectra is attributed to the electrode polarization process and can be fitted to the well-known Gerischer impedance equation. The resulting fitting parameters are used to derive surface exchange and bulk diffusion coefficients.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 548: Symposia EE – Solid State Ionics V , 1998 , 551
Copyright
Copyright © Materials Research Society 1999

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References

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