Influence of the process parameters on the spray pyrolysis technique, on the synthesis of gadolinium doped-ceria thin film

This work presents the results of a process of optimization applied to gadolinia-doped ceria (Ce0.8Gd0.2O1.9−x, or CGO) thin films, deposited by spray pyrolysis (SP). Spray pyrolysis is a high thermal deposition method that combines material deposition and heat treatment. This combination is advantageous since the post-deposition heat treatment step is not necessary. However, stresses are solidified in the coating during the deposition, which may lead to the initiation of a crack in the coating. The aim of this work was to achieve thin, dense, and continuous CGO coatings, which may be used as gas separation membranes and as a solid state electrochemical interfaces. Dense, flat, low-defect substrates such as silica slides, silicon mono crystal wafers, and porous substrates were used as substrates in this work. Cerium ammonium nitrate and gadolinium acetylacetonate were dissolved in ethanol and butyl carbitol to form a precursor solution that was sprayed on the heated substrates. Process parameters such as solvent composition, deposition rate and different heating regimes were analyzed. The microstructure was analyzed by secondary electron microscopy (SEM) and was found that thin, dense, and defect-free films could be produced on dense and porous substrates. The results obtained show that it is possible to obtain a CGO dense film deposited by spray pyrolysis. X-ray diffraction (XRD) analysis showed that the films were crystalline after the deposition without requiring post-deposition heat treatment. The crystallite size does not vary significantly as a function of the annealing temperature.

Gas-tight CGO made by spray pyrolysis suitable to be used as SOFC electrolyte.Figure optionsDownload as PowerPoint slideHighlights
► Dense and crystalline CGO films deposited by spray pyrolysis on various substrates.
► Solvent did not have a strong influence on the film microstructure, defect concentration or thickness.
► The substrate did not have a strong influence on the film microstructure, defect concentration or thickness.
► Films with at least 2.5 μm of thickness presented high impermeability.
► The films obtained are suitable to use as a SOFC electrolyte.