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Synthesis and Characterization of Gd(1−x)SrxCo(1−y)FeyO(3−Δ) as a Cathode Material for Intermediate Temperature Solid Oxide Fuel Cells

Published online by Cambridge University Press:  26 February 2011

C. R. Dyck ,
G. Yu  and
V. D. Krstic
C. R. Dyck
Affiliation:
Dept. of Mechanical Engineering, Nicol Hall, Queen's University, Kingston, ON, K7L 3N6, Canada
G. Yu
Affiliation:
Dept. of Mechanical Engineering, Nicol Hall, Queen's University, Kingston, ON, K7L 3N6, Canada
V. D. Krstic
Affiliation:
Dept. of Mechanical Engineering, Nicol Hall, Queen's University, Kingston, ON, K7L 3N6, Canada
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Abstract

Gd(1−x)SrxCoO(3−Δ) (GSC) is a promising cathode material system for use in IT-SOFCs due to its high catalytic activity for oxygen reduction and appreciable conductivity. However, it has a high thermal expansion coefficient that is unmatched to the common IT-SOFC electrolyte material, Ce0.8Gd0.2O(2−Δ) (CGO). Gd0.8Sr0.2CoO(3−Δ) (GS20C) was determined to provide the best balance of properties as a base composition in the GSC system for further study. GS20C exhibited electrical conductivity of 400 S cm−1 at 600°C and a linear thermal expansion coefficient of 23 ppm/°C. Manipulation of the Co-site in GS20C by Fe substitution to form Gd(0.8)Sr(0.2)Co(1−y)FeyO(3−Δ) (GS20CFY, Y= 0, 20, 40, 60, 80, 100 atomic%) resulted in a dramatic decrease in the thermal expansion coefficient to a level close to that of the electrolyte (∼13 ppm/°C). However, the decrease in thermal expansion was accompanied by a large decrease in the conductivity as the iron content was increased in the system (to ∼10 S cm−1). Alternatively, formation of GS20C/CGO composite cathodes resulted in thermal matching with the electrolyte material up to the IT-SOFC operating temperature of approximately 600°C with the maintenance of high electrical conductivity. Composite GS20C/CGO cathodes may reduce the problems associated with poor GSC thermal matching to the electrolyte without compromising other important cathodic properties.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 801: Symposium BB – Materials and Technologies for a Hydrogen Economy , 2003 , BB3.4
Copyright
Copyright © Materials Research Society 2004

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References

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