Properties of thick films based on La0.7Ln0.3(Mn1-xAlx)O3 as electrode materials

The layers based on La0.7Ln0.3(Mn1-xAlx)O3 (Ln + Ca or Dy, x 0; 0.3) were examined as possible cathode materials for galvanic cells and oxygen sensors. Perovskite-type oxides were prepared by a conventional solid-state reaction. Phase composition of the reaction products was controlled by a diffraction analysis and the microstructure was observed by scanning electron microscopy (SEM). In order to estimate the usability of the obtained perovskites as electrode materials, their resistivity and temperature coefficient of expansion (TEC) as well as interaction with YSZ (yttria stabilized zirconia) solid electrolyte were determined. La0.7Ln0.3(Mn1-xAlx)O3, indicating the possibility of oxygen diffusion to YSZ. For all layers the values of the sheet resistivity are high (200-400 Ohm/sq. at 900oC), because the incorporation of Ca or Dy does not the cell with La0.7Ln0.3(Mn1-xAlx)O3 cathode layer, the experimental relationship between electromotive force and temperature in the range 500-900 oC agrees well with the theoretical one, calculated from Nernst equation. (author)