Dynamic Changes in LSM Nanoparticles on YSZ: A Model System for Non-stationary SOFC Cathode Behavior
The interaction between nanoparticles of strontium-doped lanthanum manganite (LSM) and single crystal yttria-stabilized zirconia (YSZ) was investigated using atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM)/energy-dispersive x-ray spectroscopy (EDX). Nanoparticles of LSM were deposited directly onto single crystal YSZ substrates (100) using an ultrasonic spray nozzle. As samples were annealed from 850 C to 1250 C, nanoparticles gradually decreased in height and eventually disappeared completely. Subsequent reduction in H{sub 2}/H{sub 2}O at 700 C resulted in the reappearance of nanoparticles. Studies were carried out on identical regions of the sample allowing the same nanoparticles to be characterized at different temperatures. Morphological changes indicate the formation of a thin layer of LSM, and XPS results support the observation by indicating an increase in signal from the La and Sr and a decrease in signal from the Y and Zr with increasing temperature. SEM/EDX was used to verify that the nanoparticles in the reduced sample contained La. The changes in the LSM/YSZ morphology may be important in explaining the non-stationary behavior observed in operating fuel cells. The thin layer of LSM initially results in poor cathode performance; reducing conditions then lead to film disruptions, indicating nano/microporosity, that increase oxygen ion diffusion and performance.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 951667
- Report Number(s):
- LLNL-JRNL-409651; JESOAN; TRN: US200913%%89
- Journal Information:
- Journal of the Electrochemical Society, Vol. 156, Issue 5; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
29 ENERGY PLANNING
POLICY AND ECONOMY
ATOMIC FORCE MICROSCOPY
CATHODES
DIFFUSION
FUEL CELLS
LANTHANUM
MONOCRYSTALS
MORPHOLOGICAL CHANGES
MORPHOLOGY
OXYGEN IONS
PERFORMANCE
SCANNING ELECTRON MICROSCOPY
SOLID OXIDE FUEL CELLS
SUBSTRATES
ULTRASONIC WAVES
X-RAY PHOTOELECTRON SPECTROSCOPY
X-RAY SPECTROSCOPY