Oxygen mobility and surface reactivity of PrNi sub(1-x)CO sub(x)O sub(3+ delta )Ce sub(0.9)Y sub(0.1)O sub(2- delta ) cathode nanocomposites

Cobalt-doped praseodymium nickelate PrNi sub(1-x)CO sub(x)O sub(3- delta ) (PNC sub(x)) and Y-doped ceria Ce sub(0.9)Y sub(0.1)O sub( 2- delta ) (YDC) oxides were synthesized via Pechini route. PNC sub(x) YDC composites were prepared via ultrasonic dispersion of the mixture of perovskite and fluorite nanopowders in isopropanol with addition of polyvinyl butyral followed by drying, pressing and sintering at 1300 [degrees]C The oxygen mobility and reactivity of powdered PNC sub(X) and composites obtained by crushing and milling of dense pellets were estimated by O sub(2)-TPD and oxygen isotope exchange with super(18)O sub(2) and C super(18)O sub(2) using both static and flow (SSIKA) reactors in isothermal and temperature-programmed (TPIE) modes. For PNC sub(x) samples sintered at 1300 [degrees]C comprised of (Ni,Co)O and Ruddlesden-Popper type phases (Pr sub(2)NiO sub(4), Pr sub(4)(Ni,Co) sub(3)O sub(10)), the oxygen mobility and reactivity tend to decrease with Co content For composites, the oxygen mobility is much higher due to Pr transfer into YDC thus disordering perovskite-like and fluorite-like phases. TPIE C super(18)O sub(2) SSITKA experiments combined with SIMS analysis of the depth profiles of Pr super(18)O and Ce super(18)O suggest that fast oxygen diffusion in composites is provided by domains of disordered perovskite-like phases as well as Pr, Y-doped ceria. For best composites, the value of the oxygen chemical diffusion coefficient estimated by the weight relaxation technique exceeds that of well known LSFC-GDC composite.