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SURFACE SEGREGATION STUDIES OF SOFC CATHODES: COMBINING SOFT X-RAYS AND ELECTROCHEMICAL IMPEDENCE SPECTROSCOPY

Published online by Cambridge University Press:  31 January 2011

Lincoln Miara ,
Louis Piper ,
Jacob Nathan Davis ,
Laxmikant Saraf ,
Tiffany Kaspar ,
Soumendra Basu ,
Kevin E. Smith ,
Uday B. Pal  and
Srikanth Gopalan
Lincoln Miara
Affiliation:
[email protected], Boston University, Division of Materials Science, Brookline, Massachusetts, United States
Louis Piper
Affiliation:
[email protected], Boston University, Physics, Boston, Massachusetts, United States
Jacob Nathan Davis
Affiliation:
[email protected], Boston University, Division of Materials Science, Brookline, Massachusetts, United States
Laxmikant Saraf
Affiliation:
[email protected], Pacific Northwest National Laboratory, Environmental and Molecular Laboratory, Richland, Washington, United States
Tiffany Kaspar
Affiliation:
[email protected], Pacific Northwest National Laboratory, Environmental and Molecular Laboratory, Richland, Washington, United States
Soumendra Basu
Affiliation:
[email protected], Boston University, Division of Materials Science and Engineering, 15 St. Mary's Street, Brookline, Massachusetts, 02446, United States
Kevin E. Smith
Affiliation:
[email protected], Boston University, Physics, Boston, Massachusetts, United States
Uday B. Pal
Affiliation:
[email protected], Boston University, Division of Materials Science, Brookline, Massachusetts, United States
Srikanth Gopalan
Affiliation:
[email protected], Boston University, Division of Materials Science, Brookline, Massachusetts, United States
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Abstract

A system to grow heteroepitaxial thin-films of solid oxide fuel cell (SOFC) cathodes on single crystal substrates was developed. The cathode composition investigated was 20% strontium-doped lanthanum manganite (LSM) grown by pulsed laser deposition (PLD) on single crystal (111) yttria-stabilized zirconia (YSZ) substrates. By combining electrochemical impedance spectroscopy (EIS) with x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy XAS measurements, we conclude that electrically driven cation migration away from the two-phase gas-cathode interface results in improved electrochemical performance. Our results provide support to the premise that the removal of surface passivating phases containing Sr2+ and Mn2+, which readily form at elevated temperatures even in O2 atmospheric pressures, is responsible for the improved cathodic performance upon application of a bias.

Keywords

x-ray photoelectron spectroscopy (XPS)thin filmelectronic structure
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1217: Symposium Y – Catalytic Materials for Energy, Green Processes and Nanotechnology , 2009 , 1217-Y07-04
Copyright
Copyright © Materials Research Society 2010

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