In this paper, the deposition of Ca3Co4O9+δ layers on CGO substrates using electrostatic spray deposition (ESD) technique, starting from calcium and cobalt nitrates as precursor salts, is reported. The microstructure was investigated as a function of process parameters such as nozzle-to-substr...
In this paper, the deposition of Ca3Co4O9+δ layers on CGO substrates using electrostatic spray deposition (ESD) technique, starting from calcium and cobalt nitrates as precursor salts, is reported. The microstructure was investigated as a function of process parameters such as nozzle-to-substrate distance, solvent composition, substrate temperature, flow rate and deposition time, based on an upper and a lower value. Films with controlled microstructures were obtained after annealing at 880oC for 2h in air. The formation of Ca3Co4O9+δ was confirmed by X-ray diffraction, which also showed evidence of Co3O4 traces. As shown by in-situ X-ray diffraction, Ca3Co4O9+δ starts to form at 625oC and decomposes at 950oC, but the transformation is reversible. Interestingly, the initial morphology of the films was maintained after annealing at either 700 or 880oC, with the appearance of faceted crystals forming a gypsum flower-like microstructure. AC impedance spectroscopy was carried out at intermediate temperatures (600-800oC) under air on 2 batches of symmetrical cells based on ESD and screen-printed electrodes, respectively. This work confirmed the beneficial impact of the ESD technique. The area-specific resistance was improved by at least 23% at 600oC and 40% at 800oC for the sample prepared by ESD compared to the reference one prepared by screen printing. This improvement was explained by a better interface between the electrode and the electrolyte.
In this paper, the deposition of Ca3Co4O9+δ layers on CGO substrates using electrostatic spray deposition (ESD) technique, starting from calcium and cobalt nitrates as precursor salts, is reported. The microstructure was investigated as a function of process parameters such as nozzle-to-substrate distance, solvent composition, substrate temperature, flow rate and deposition time, based on an upper and a lower value. Films with controlled microstructures were obtained after annealing at 880oC for 2h in air. The formation of Ca3Co4O9+δ was confirmed by X-ray diffraction, which also showed evidence of Co3O4 traces. As shown by in-situ X-ray diffraction, Ca3Co4O9+δ starts to form at 625oC and decomposes at 950oC, but the transformation is reversible. Interestingly, the initial morphology of the films was maintained after annealing at either 700 or 880oC, with the appearance of faceted crystals forming a gypsum flower-like microstructure. AC impedance spectroscopy was carried out at intermediate temperatures (600-800oC) under air on 2 batches of symmetrical cells based on ESD and screen-printed electrodes, respectively. This work confirmed the beneficial impact of the ESD technique. The area-specific resistance was improved by at least 23% at 600oC and 40% at 800oC for the sample prepared by ESD compared to the reference one prepared by screen printing. This improvement was explained by a better interface between the electrode and the electrolyte.
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