[Zurück]

M. Kubicek, T. Huber, A. Wachter-Welzl, A. Penn, G. M. Rupp, J. Bernardi, M. Stöger-Pollach, H. Hutter, J. Fleig:
"Electrochemical properties of La_0.6Sr_0.4CoO_3−δ thin films investigated by complementary impedance spectroscopy and isotope exchange depth profiling";
Solid State Ionics, 256 (2014), S. 38 - 44.

Cation diffusion was investigated in La0.6Sr0.4CoO3-δ (LSC) thin films on (100) yttria stabilized zirconia in the temperature range 625-800 °C. Isotopic ((86)Sr) and elemental tracers (Fe, Sm) were used to establish diffusion profiles of the cations in bi- and multi-layered thin films. The profiles were analyzed by time of flight-secondary ion mass spectrometry (ToF-SIMS). Grain and grain boundary diffusion coefficients of the cations were determined for LSC thin films with columnar grains - diffusion along grain boundaries is shown to be about three orders of magnitude faster than in grains. This could be verified for thin films with different grain size. A- and B-site cations showed very similar temperature dependencies with activation energies of ∼3.5 eV for bulk and ∼4.1 eV for grain boundary diffusion. The importance of cation diffusivities for surface segregation of Sr and thus for a major degradation mechanism of LSC cathodes in solid oxide fuel cells is discussed.

Mixed conductor,Impedance spectroscopy,Isotope exchange,Surface exchange,Diffusion,ToF-SIMS

http://dx.doi.org/10.1016/j.ssi.2013.12.016

http://publik.tuwien.ac.at/files/PubDat_227512.pdf