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

Aerosol-assisted metallo-organic CVD (MOCVD) method (spray pyrolysis) has b een employed to deposit thin films of solid electrolyte onto dense (NiO + Y DC) substrates in our laboratory. The beta -diketonate precursors Ce(tmhd)( 4) and Y(tmhd)(3) were chosen as the source materials for deposition of ytt ria-doped ceria (YDC) thin films in the temperature range 500-700 degreesC. Scanning electron microscopy (SEM) observation revealed the YDC films to h ave uniform and nanometric grains, with thickness ranging from 0.18 to 1.2 mum with different deposition times. X-ray diffraction (XRD) analyses showe d 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 deposit ion temperature 600 degreesC. After being reduced in an H-2 atmosphere at 6 00 degreesC 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 thi n film on (Ni + YDC) substrate was slightly less than that of YDC prepared by sintering, but higher than that of yttria-stabilized zirconia (YSZ). The se results suggest that the YDC thin film obtained by aerosol-assisted MOCV D is a potential solid electrolyte alternative to YSZ, at intermediate oper ating temperatures, for solid oxide fuel cell (SOFC) applications. (C) 2001 Elsevier Science Ltd. All rights reserved.