Investigation of surface Sr segregation in model thin film solid oxide fuel cell perovskite electrodes
- Creators
- Jung, WooChul
- Tuller, Harry L.
Abstract
While SOFC perovskite oxide cathodes have been the subject of numerous studies, the critical factors governing their kinetic behavior have remained poorly understood. This has been due to a number of factors including the morphological complexity of the electrode and the electrode- electrolyte interface as well as the evolution of the surface chemistry with varying operating conditions. In this work, the surface chemical composition of dense thin film SrTi_(1−x)Fe_xO_(3-δ) electrodes, with considerably simplified and well-defined electrode geometry, was investigated by means of XPS, focusing on surface cation segregation. An appreciable degree of Sr-excess was found at the surface of STF specimens over the wide composition range studied. The detailed nature of the Sr-excess is discussed by means of depth and take-off angle dependent XPS spectra, in combination with chemical and thermal treatments. Furthermore, the degree of surface segregation was successfully controlled by etching the films, and/or preparing intentionally Sr deficient films. Electrochemical Impedance Spectroscopy studies, under circumstances where surface chemistry was controlled, were used to examine and characterize the blocking effect of Sr segregation on the surface oxygen exchange rate.
Additional Information
© 2012 Royal Society of Chemistry. Received 27th September 2011, Accepted 25th October 2011. First published on the web 07 Nov 2011. This work was initially supported by the Ceramics Program, Division of Materials Research Directorate for Mathematical & Physical Sciences, National Science Foundation under award DMR-0243993 and continued under the Materials Science and Engineering Division, Office of Basic Energy Sciences, Department of Energy under award DE SC0002633. W.J. Thanks the Samsung Foundation for fellowship support. The authors thank Dr R.A. De Souza and Dr J. Fleig for helpful discussions. The Xray, XPS and AFM facilities of the Center for Materials Science and Engineering, an NSF MRSEC funded facility were used in this study.Attached Files
Published - Jung2012p17288Energ_Environ_Sci.pdf
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Additional details
- Eprint ID
- 29459
- Resolver ID
- CaltechAUTHORS:20120224-113124738
- DMR-0243993
- NSF Division of Materials Research Directorate for Mathematical & Physical Sciences
- DE SC0002633
- Department of Energy (DOE) Materials Science and Engineering Division, Office of Basic Energy Sciences
- Samsung Foundation Fellowship
- NSF MRSEC
- Created
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2012-02-24Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field