Comparative Study of Electrophoretic Deposition of Doped BaCeO3-Based Films on La2NiO4+δ and La1.7Ba0.3NiO4+δ Cathode Substrates

Abstract

This paper presents the results of a comparative study of methods to prevent the loss of barium during the formation of thin-film proton-conducting electrolyte BaCe0.89Gd0.1Cu0.01O3−δ (BCGCuO) on La2NiO4+δ-based (LNO) cathode substrates by electrophoretic deposition (EPD). Three different methods of the BCGCuO film coating were considered: the formation of the BCGCuO electrolyte film without (1) and with a protective BaCeO3 (BCO) film (2) on the LNO electrode substrate and the formation of the BCGCuO electrolyte film on a modified La1.7Ba0.3NiO4+δ (LBNO) cathode substrate (3). After the cyclic EPD in six stages, the resulting BCGCuO film (6 μm) (1) on the LNO substrate was completely dense, but the scanning electron microscope (SEM) analysis revealed the absence of barium in the film caused by its intensive diffusion into the substrate and evaporation during the sintering. The BCO layer prevented the barium loss in the BCGCuO film (2); however, the protective film possessed a porous island structure, which resulted in the deterioration of the film’s conductivity. The use of the modified LBNO cathode also effectively prevented the loss of barium in the BCGCuO film (3). A BCGCuO film whose conductivity behavior most closely resembled that of the compacts was obtained by using this method which has strong potential for practical applications in solid oxide fuel cell (SOFC) technology.

Features of Electrophoretic Deposition of a Ba-Containing Thin-Film Proton-Conducting Electrolyte on a Porous Cathode Substrate

“…As a result of increasing the electrolyte thickness to 21 µm, it was possible to retain barium in the BCGCuO electrolyte layer, which is confirmed by the spatial distribution of elements in the coating (Figure 7b,c). According to the EDX data, La diffusion into the electrolyte layer (~1.2 at.%) occurred but its distribution in the electrolyte layer was quite uniform (Figure 7c) compared to the results of deposition of a BCGCuO film on a dense LBNO ss substrate [16], when in the electrolyte film, the sections of its heterogeneous accumulation were visible. The Gd content in the film was slightly reduced (~0.7 at.%) in both films-obtained in this study and in [16]-which may be associated with its diffusion into the substrate.…”

“…BaCO 3 (98.4% purity, Vekton, Russia), Gd(NO 3 ) 3 •6H 2 O (99%, Reaktiv, Russia), Ce(NO 3 ) 3 •6H 2 O (99%, Reaktiv, Russia), and CuO (99%, Reakhim, Russia) were used as raw materials; glycine and citric acid were used as a fuel and oxidizer, respectively. The details of the synthesis procedure are given elsewhere [16]. Following the final synthesis stage at 1050 • C (10 h), the BCGCuO powder was grinded for 2 h in a Pulverisette 6 planetary mill (Fritsch, Germany) in a Teflon drum with tetragonal ZrO 2 -Y 2 O 3 milling bodies in an isopropyl alcohol medium (weight ratio of 1:5:1).…”

“…EPD of BCGCuO films with a thickness of approximately 6 µm on a model dense LBNO ss cathode in our earlier study [16] was carried out by multiple deposition/sintering cycles (12 cycles). The suspension in this case was subjected to ultrasonic treatment (UST), followed by centrifugation and removal of aggregates larger than 1 µm.…”

“…Recently, our group has presented several studies on electrophoretic deposition (EPD) of BaCeO 3 -based films on dense cathode substrates [15,16]. The EPD process is carried out on the electrodes immersed in a suspension of ceramic particles, between which a potential difference is set.…”

“…The problem of redistribution and barium depletion in BaCeO 3 -based films with a thickness of less than 10 microns was considered in a number of studies where various strategies were proposed to prevent cation disbalance in the sintered films, for example, sintering a film in a powder of the same composition or BaCeO 3 [21] or application of a protective BaCeO 3 layer on the top of the film before its sintering [22]. In [16], a study was conducted of the methods for forming a thin-film electrolyte BaCe 0.89 Gd 0.1 Cu 0.01 O 3-δ (BCGCuO) on dense model substrates La 2 NiO 4+δ (LNO) and La 1.7 Ba 0.3 NiO 4+δ (LBNO) by the EPD method. In particular, a BCGCuO film was deposited on a LNO substrate and a half-cell was sintered in the BCGCuO powder; a BCGCuO film was deposited on a LNO substrate and a BaCeO 3 protective film was deposited on the top of the BCGCuO film and co-sintered; the BCGCuO film was deposited on a LBNO substrate followed by sintering.…”