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

Abstract

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 H 2 atmosphere at 600°C for 10 h, the (NiO + YDC) substrate was converted into Ni + YDC. The YDC thin film was found to be N 2 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.