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Title:
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Electrode properties of Sr-doped LaMnO3 on yttria stabilized zirconia: pt.1: three-phase boundary area
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Author(s):
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Published by:
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Publication date:
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ECN
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1996
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ECN report number:
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Document type:
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ECN-RX--96-014
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Other
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Number of pages:
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Full text:
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30
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Download PDF
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Abstract:
The interface microstructure of the state-of-the-art cathode material forsolid oxide fuel cells (SOFC's), SrxLa1-xMnO3 (SLM), was investigated
with respect to its electrochemical performance. The interface microstructure
was characterised by the grain size and the coverage of SLM on the
electrolyte surface. Variation of the grain size was obtained by using three
different sintering temperatures whereas variation of the coverage was
obtained by using two powders with a different morphology. This resulted in a
set of six cathode/electrolyte samples with different combinations of grain
size and SLM coverage at the interface. The cathode overpotential, as a
measure for the electrochemical performance, could not be related to the
length of the three-phase boundary (tpb). Based on the constriction
resistance occurring in the electrolyte a model was developed which provides
an estimate for the width of the active tpb zone. This zone is most likely to
extend outside the cathode particle across the zirconia surface. The width
calculated in this way was found to vary in the range of 0.03-0.07mum for
the different electrode micro structures. It is argued that the actual values
may be smaller by an order of magnitude. 14 figs., 5 tabs., 12 refs.
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