Electrophoretic Deposition of Thin-Film Coatings of Solid Electrolyte Based on Microsize BaCeO3 Powders

Abstract

Results are presented of an electrophoretic deposition of thin-film coatings based on doped barium cerate BaCeO₃ on a cathode substrate La₂NiO₄ (LNO), which are of interest for the technology of medium-temperature solid-oxide fuel cells. Suspensions for electrophoretic deposition in a mixed dispersion medium isopropanol/acetylacetone = 70/30 vol %, prepared from microsized powders BaCe_0.8Sm_0.2O_3–δ (BCSO) and BaCe_0.89Gd_0.1Cu_0.01O_3–δ (BCGCuO) synthesized by the citrate-nitrate method, demonstrated a high positive ζ-potential (+25 mV) suitable for deposition. A combination of the ultrasonic treatment and centrifugation made it possible to diminish the hydrodynamic diameter of BCSO and BCGCuO particles to 880 and 294 nm, respectively. It was shown that the BCGCuO film deposited onto an LNO cathode substrate has a higher density as compared with the BCSO film, which is due to the properties of the suspensions obtained. Upon a cyclic electrophoretic deposition in six stages, the total mass and thickness of the BCGCuO coating were 3.2 mg cm^–2 and 5 μm, which is sufficient for a unit solid-oxide cell to be formed. According to SEM data, the BCGCuO film is dense and has fully formed grains with sizes of 1 to 7 μm. Methods are discussed for eliminating the loss of Ba in sintering of a thin film based on BaCeO₃.