Swedenborgite-type oxides YBaCo4-xZnxO7+δ (x = 0.8, 1) as cathode materials for IT-SOFCs
Dmitry Tsvetkov, Ural Federal University, Ekaterinburg, Russian FederationNadezhda Tsvetkova, Ural Federal University, Ekaterinburg, Russian FederationAndrey Zuev, Ural Federal University, Ekaterinburg, Russian Federation
The YBaCo4O7+δ oxide is considered as promising cathode material for intermediate temperature SOFCs due to lower thermal expansion coefficient (TEC) as compared to other cobalt-containing complex oxides . The main disadvantage of YBaCo4O7+δ is its instability in the temperature range of 700–900 °C due to oxidation in the oxygen-containing atmosphere . However, the substitution of Zn for Co is believed to enhance the stability of YBaCo4O7+δ . The present work is devoted to study of YBaCo4-xZnxO7+δ (x = 0.8, 1) oxides as cathode materials for IT-SOFCs based on Ce0.8Sm0.2O1.9 solid electrolyte.
The YBaCo4-xZnxO7+δ (x = 0.8, 1) and Ce0.8Sm0.2O1.9 powders were prepared by glycerin-nitrate method. The products obtained were characterized by X-Ray diffraction using Shimadzu XRD-7000 diffractometer (Cu Kα radiation). The chemical reactivity tests were carried out by mixing the YBaCo4-xZnxO7+δ (x = 0.8, 1) and the Ce0.8Sm0.2O1.9 powders with subsequent calcination at different temperatures. Thermal expansion coefficients of the samples were evaluated using dilatometer NETZSCH DIL 402 C in the temperature range 30–1100 °C in air. Electrical conductivity of the samples was measured with a four-probe direct current method in the temperature range 30–1100 °C in air. Polarization measurements were carried out by electrochemical impedance spectroscopy with an “Elins Z500-PX” impedance analyzer in the frequency range 10 Hz–0.5 MHz and temperature range 600–750 °C with 25 °C steps.
Acknowledgement: This work was supported by the project SP-3440.2016.1 funded by the President of the Russian Federation.
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