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.
Revised: February 10, 2011 |
Published: December 1, 2010
Citation
Miara L.J., L. Piper, J.N. Davis, L.V. Saraf, T.C. Kaspar, S. Basu, and K.E. Smith, et al. 2010.SURFACE SEGREGATION STUDIES OF SOFC CATHODES: COMBINING SOFT X-RAYS AND ELECTROCHEMICAL IMPEDENCE SPECTROSCOPY. In Materials Research Society (MRS) Symposium Proceedings: Catalytic Materials for Energy, Green Processes and Nanotechnology, November 30 - December 3, 2009, Boston, MA, edited by CY Mou, S Dai, HH Kung and J Liu, 1217, 145-150. Warrendale, Pennsylvania:Materials Research Society.PNNL-SA-70211.