Abstract: State-of-the-art SOFC cathode materials based upon LS(F)C are deteriorated in the intermediate temperature (IT) range due to formation of carbonates blocking surface sites [1]. Stable to carbonation PrNi1 xCoxO3 δ –doped ceria composites demonstrated a high performance in the IT range [2]. This work aims at elucidating effects of composition and microstructure of such materials on Pr1-ySmyNi1-xCoxO3 δ oxygen mobility and reactivity. Perovskite (P) Pr1-xSmxNi0.5Co0.5O3-δ (PSNC) and fluorite (F) Ce0.9Y0.1O2 (YDC) oxides were synthesized by Pechini route. PSNC–YDC composites were prepared by ultrasonic dispersion of powders mixture in isopropanol, then drying, pressing pellets and sintering at 800 – 1300 °C. Samples were characterized by XRD and TEM with EDX. Oxygen mobility was estimated by O2 TPD and oxygen isotope heteroexchange with 18O2 and C18O2. For PSNC samples sintered at 700 – 1000 °C the main phase is orthorhombic perovskite with parameter ~ 5.450 Å. Admixture of cubic Fm 3m phase with composition Pr0.6Sm0.1(Ni,Co)0.3O2-δ according to EDX data is present, its amount decreasing with sintering temperature. For PSNC samples sintered at 1100 °C besides P phase only small amount of A4B3O10 Ruddlesden – Popper (RP) homologue is found. For samples sintered at 1200 – 1300 °C RP Pr3.5Sm0.5Ni1.5Co1.5O10+δ is the main phase with some traces of P and Ni(Co)O (Fig.1). For PSNC – YDC composites strong cations redistribution is observed. For samples sintered at ≥1000 °C the main phase is F with P amount decreasing with sintering temperature. At 700 °C oxygen tracer diffusion coefficient DO and surface exchange constant kex are ~10-8 cm2/s and ~10-7 cm/s, respectively, for PSNC sintered at 1100 °C. For PSNC – YDC composites these values are by about one order of magnitude higher. Such high oxygen mobility can be explained by disordering domains and P-F interface. Also Pr, Sm and Y-doped ceria itself shows a high oxygen mobility (DO ~10-6 cm2/s at 700 °C) [3] [1] E. Bucher and W. Sitte, Long-term stability of the oxygen exchange properties of (La,Sr)1−z(Co,Fe)O3−δ in dry and wet atmospheres, Solid State Ionics, vol. 192, pp. 480-482, (2011). [2] S. Huang, Q. Lu, et al, PrNi0,6Co0,4O3 ‒ Ce0,8Sm0,2O1,9 composite cathodes for intermediate temperature solid oxide fuel cells. // Journal of Power Sources, Journal of Power Sources, vol. 199, pp. 150-154, (). [3] V. Sadykov, N. Eremeev, et al, Oxygen mobility and surface reactivity of PrNi1−xCoxO3−δ perovskites and their nanocomposites with Ce0.9Y0.1O2−δ by temperature-programmed isotope exchange experiments, Solid State Ionics, http://dx.doi.org/10.1016/j.ssi.2014.11.021 (2014).

Cite: Sadykov V.A. , Eremeev N.F. , Amanbayeva D.G. , Krieger T.A. , Fedorova Y.E. , Bobin A.S. , Pelipenko V.V. , Sadovskaya E.M. , Muzykantov V.S. , Ishchenko A.V.
Sm-Doped Praseodymium Nickelates-Cobaltites and Their Nanocomposites as Promising Cathode Materials
In compilation Functional Materials and Nanotechnologies (FM&NT-2015). 2015. – C.88.

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