168 Prakt. Met. Sonderband 46 (2014)
restructuring of silver films after heat treatment has been reported in the literature for various EFFEC
ceramic substrates (e.g. [8-10]). Although annealing temperatures were kept below the GLASS
melting point of silver, the morphology of the silver particles resembles that of a substrate
covered by a poorly wetting liquid. This is in agreement with the generally observed trend DIFFER
that mid-to-late transition metals do not wet binary metal oxides [11].
R. Bermej
|. Petsche
4. SUMMARY + ;
_ Institut ı
Chemical diffusion coefficients of oxygen (Dchem) have been obtained from bar-shaped .. Materia
samples of La2NiO4+5 by means of the conductivity relaxation technique. For the uncoated TDK-EF
material the surface exchange reaction was found to be the rate-determining step for the
overall oxygen exchange process, thus preventing any investigations on diffusion kinetics.
After the deposition of a ~200 nm thick Ag-layer on the sample surface, the chemical oxygen
surface exchange coefficient (kchem) was increased by roughly one order of magnitude at ABSTR/
600°C due to the catalytic activity of silver for the oxygen surface exchange reaction. This
effect was used to obtain reliable values of oxygen diffusivities. Post-test XPS-depth profiles Glass-cer:
confirm that silver is completely removed via gas phase transport at higher temperatures. are widely
Ag-films deposited on polished test specimens of La:NiOs+5 were annealed between 500 communic
and 800°C and pronounced restructuring and agglomeration of the metallization layer was particle siz
observed. In additior
(commonl
LTCC syst
ACKNOWLEDGMENTS balls), con
LTCC ma
This work has been financially supported by the Austrian Klima- und Energiefonds and AVL (comparec
List GmbH within the project RELIVE-CAT (project no. 825566, Neue Energien 2020). surface |
Treibacher Industrie AG is acknowledged for providing LazNiOs-powder. The authors thank coefficient
the Department of Physical Metallurgy and Materials Testing (Montanuniversitét Leoben) for measured
providing SEM-facilities as well as Gerhard Hawranek for SEM-operation.
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