Influence of various lanthanides on the properties of Sr0.8Ce0.1Ln0.1MnO3 − δ and Sr0.9Ce0.05Ln0.05CoO3 − δ ceramics and thick film electrodes

In this work nonstoichiometric strontium cerium manganites and cobaltites Sr0.8Ce0.1Ln0.1MnO3 − δ and Sr0.9Ce0.05Ln0.05CoO3 − δ with low content of various lanthanides (Ln = La, Ce, Nd, Sm, Gd, Dy, Yb) were investigated as potential electrode materials for solid state fuel cells and gas sensors. Synthesis and sintering conditions as well as dc resistivities and thermal expansion coefficients of the developed ceramics in the range 20–900 °C were studied. On the basis of complex impedance spectroscopic studies of yttria stabilized zirconia solid electrolyte samples with thick film perovskite electrodes four contributions to the dielectric response were found, attributed to the grains and the grain boundaries of the solid electrolyte, to the electrode–electrolyte interface and to the electrodes, in the descending order of frequency. Dc conductivity of the ceramic samples and thick films exhibited semiconducting, semimetallic or metallic character, depending on the composition and the examined temperature range. In the temperature range of 600–900 °C, a very good agreement was found between the experimental and the theoretical values of electromotive force of concentration oxygen cells based on zirconia solid electrolyte with perovskite electrodes.