La0.6Sr0.4CoO3–δ (LSC) thin‐film electrodes are prepared on yttria‐stabilized zirconia (YSZ) substrates by pulsed laser deposition at different deposition temperatures. The decrease of the film crystallinity, occurring when the deposition temperature is lowered, is accompanied by a strong increase of the electrochemical oxygen exchange rate of LSC. For more or less X‐ray diffraction (XRD)‐amorphous electrodes deposited between ca. 340 and 510 °C polarization resistances as low as 0.1 Ω cm2 can be obtained at 600 °C. Such films also exhibit the best stability of the polarization resistance while electrodes deposited at higher temperatures show a strong and fast degradation of the electrochemical kinetics (thermal deactivation). Possible reasons for this behavior and consequences with respect to the preparation of high‐performance solid oxide fuel cell (SOFC) cathodes are discussed.

The crystal structure of K 2 Al 2 O 3 F 2, prepared at 800°C by ceramic methods, was determined from conventional laboratory X-ray powder diffraction data. The compound crystallizes in the monoclinic space group C2/m (No. 12) with a = 11.21675(8), b = 8.16351 (6), c = 6.12301(5) Å β = 88.8108(6)°and Z = 4. Unit cell and space group suggestions were found by using the TOPAS program. Starting positional parameters for potassium and aluminum atoms were obtained from 548 reflections by the methods implemented in the FOX program. Oxygen and fluorine atom positions were determined by structural con-* Univ. Prof. Dr. F. Kubel Fax: +43-1-58801-17199 E-Mail: Frank.Kubel@tuwien.ac.at [a]

La 0.6 Sr 0.4 CoO 3−δ (LSC) thin film electrodes of about 80 nm thickness were prepared via a sol-gel route on yttria-stabilized zirconia (YSZ) and gadolinium doped ceria (GDC) solid electrolytes. Impedance measurements on microelectrodes fabricated from these films revealed very low polarization resistances for electrochemical oxygen exchange at intermediate temperatures (500-600 • C). Prerequisite for the very fast oxygen reduction kinetics was a limitation of the preparation (annealing) temperature to 600 • C. Already after ca. 15 minutes annealing of the sol-gel prepared layer at this temperature, electrodes were electrochemically highly active despite low crystallinity (almost XRD amorphous). LSC electrodes on GDC showed much higher polarization resistances. However, this originated from an additional interfacial resistance rather than from kinetically slow LSC surfaces.

The title compound is prepared by reaction of Al(OH)3 and KF powders (Pt crucible, 800°C, 18 h; 96 wt.% yield). K2Al2O3F2 crystallizes in the monoclinic space group C2/m with Z = 4 (powder XRD). The crystal structure consists of individual layers of oxygen connected AlO3F tetrahedral groups with fluorine atoms separating the layers. Conductivity measurements from room temperature to 300°C show decent potassium ion conductivity. -(KUBEL*, F.; FLEIG, J.; PANTAZI, M.; JANUSCHEWSKY, J.; Z. Anorg. Allg. Chem. 637 (2011) 1, 41-45, http://dx.

The polarization resistance of La0.6Sr0.4CoO3-δ thin film electrodes prepared via pulsed laser deposition (PLD) is investigated by impedance spectroscopy for various film deposition temperatures. The electrodes were deposited on yttria stabilized zirconia (YSZ) single crystals and polycrystals and on polycrystalline gadolinia doped ceria (CGO). Structure-property relations emphasizing the correlation between crystallinity and performance are determined by additional XRD, SEM and TEM measurements. These experiments revealed that thin film electrodes of extraordinary low polarization resistance and little degradation may be produced on YSZ by optimizing the deposition conditions.