title: Cation diffusion in La(0.6)Sr(0.4)CoO(3-δ) below 800 °C and its relevance for Sr segregation.
abstract: 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.
authors.affiliation: Institute of Chemical Technologies and Analytics Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria. markus.kubicek@tuwien.ac.at.
authors.forename: Markus
authors.initials: M
authors.lastname: Kubicek
authors.forename: Ghislain M
authors.initials: GM
authors.lastname: Rupp
authors.forename: Stefanie
authors.initials: S
authors.lastname: Huber
authors.forename: Alexander
authors.initials: A
authors.lastname: Penn
authors.forename: Alexander K
authors.initials: AK
authors.lastname: Opitz
authors.forename: Johannes
authors.initials: J
authors.lastname: Bernardi
authors.forename: Michael
authors.initials: M
authors.lastname: Stöger-Pollach
authors.forename: Herbert
authors.initials: H
authors.lastname: Hutter
authors.forename: Jürgen
authors.initials: J
authors.lastname: Fleig