Regensburg 2019 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 20: Poster session II

MM 20.36: Poster

Dienstag, 2. April 2019, 18:30–20:00, Poster C

In Situ Impedance Analysis of LSC Thin Films during Growth on YSZ and LSGM — •Matthäus Siebenhofer, Ghislain M. Rupp, Jürgen Fleig, and Markus Kubicek — Institute of Chemical Technologies and Analytics, Vienna University of Technology

The mixed conducting perovskite material La_0.6Sr_0.4CoO_3−δ (LSC) is a very promising cathode material for application in a solid oxide fuel cell (SOFC) due to its catalytic properties for the oxygen surface exchange and its high electronic conductivity. A factor which is essential to consider in the characterization of LSC is the influence of lattice strain on the surface exchange resistance and the chemical capacitance. Recent findings showed that tensile strained films exhibit faster surface exchange and diffusion compared to compressively strained films.

In this study the influence of the two different substrates Y₂O₃:ZrO₂ and (La,Sr)(Ga,Mg)O₃ on LSC thin films was examined with a novel method allowing in situ impedance spectroscopy during the PLD process (IPLD). That way, it is possible to track charge carrier densities during growth and to link the results with microstructure and strain.

According to the measurements, tensile strain leads to an increase of the chemical capacitance by a factor of 1.6 and therefore to an increase of the effective concentration of oxygen vacancies. Furthermore a decrease of the surface exchange resistance by 50 % was observed. These results are also in agreement with previous theoretical studies which suggest that tensile in-plane lattice strain lowers the vacancy formation energy and therefore increases the vacancy concentration.