Aerosol-assisted MOCVD deposition of YDC thin films on (NiO + YDC) substrates

Aerosol-assisted metallo-organic CVD (MOCVD) method (spray pyrolysis) has been employed to deposit thin films of solid electrolyte onto dense (NiO + YDC) substrates in our laboratory. The β-diketonate precursors Ce(tmhd)4 and Y(tmhd)3 were chosen as the source materials for deposition of yttria-doped ceria (YDC) thin films in the temperature range 500–700°C. Scanning electron microscopy (SEM) observation revealed the YDC films to have uniform and nanometric grains, with thickness ranging from 0.18 to 1.2 μm with different deposition times. X-ray diffraction (XRD) analyses showed that the films possessed a single phase with a fluorite cubic structure. X-ray photoelectron spectroscopy (XPS) showed that the elemental ratio Y/Ce of the film was close to that of the mixed solution precursor at a deposition temperature 600°C. After being reduced in an H2 atmosphere at 600°C for 10 h, the (NiO + YDC) substrate was converted into Ni + YDC. The YDC thin film was found to be N2 leak tight up to the pressure of 0.65 MPa. AC impedance analyses showed that the ionic conductivity of YDC thin film on (Ni + YDC) substrate was slightly less than that of YDC prepared by sintering, but higher than that of yttria-stabilized zirconia (YSZ). These results suggest that the YDC thin film obtained by aerosol-assisted MOCVD is a potential solid electrolyte alternative to YSZ, at intermediate operating temperatures, for solid oxide fuel cell (SOFC) applications.