Studies on spray deposited NiO-SDC composite films for solid oxide fuel cells

Adherent, porous and catalytically active composite films of NiO-SDC (Ce0.8Sm0.2O1.9), cermet were synthesized by spray pyrolysis technique at substrate temperature 350 deg. C and annealing temperature 500 deg. C. X-ray diffraction studies confirmed the formation of composite film with separate phases corresponding to cubic NiO and SDC. SEM study has shown the formation of non-uniform film consisting of three-phase boundaries between pores, NiO and SDC phases. EDAX studies revealed the presence of Ce, Sm and Ni elements in the film. From AFM study, grain size and surface roughness of the film were found to be 30 and 3 nm, respectively. Catalytic activity of the film was studied in the presence of hydrogen and found to increase with increase in temperature. In higher frequency region, the impedance response was a single semicircle, corresponding to the oxygen ion migration in the bulk. Frequency dependent properties, such as AC conductivity, dielectric constant and dielectric loss were also studied. The AC conductivity of the film increased with increase in frequency, showing the conduction through small polaron hopping mechanism, which is favorable for NiO-SDC composite to be used as an anode material in solid oxide fuel cells