This study demonstrates the significant impact of Cr on the electronic conductivity of a LaNi0.6Fe0.4O3 (LNF) porous cathode layer at 800 °C. Vapor transport of Cr-species, originating from a porous metallic foam, and subsequent reaction with LNF, results in a decrease of the electronic conductivity of the LNF-layer. Cr has been detected throughout the entire cross-section of a 16 μm thick LNF layer, while Ni, besides its compositional distribution in the LNF layer, has also been found in enriched spots forming Ni-rich metal oxide crystals. Transmission electron microscopy revealed that Cr is gradually incorporated into the LNF-grains, while Ni is proportionally expelled. Electron diffraction performed in the center of a sliced grain showed the initial rhombohedral crystal structure of LNF, whereas diffraction performed close to the edge of the grain revealed the orthorhombic perovskite crystal structure, indicating a Cr-enriched perovskite phase. Progressive Cr deposition and penetration into the LNF grains and necks explains the electronic conductivity deterioration. The impact of Cr-poisoning on the electronic conductivity of the LNF porous layer is considerably smaller at 600 °C than at 800 °C.
- SOFC interconnect
- SOFC cathode
- Cr vapor transport
Stodolny, M. K., Boukamp, B. A., Blank, D. H. A., & van Berkel, F. P. F. (2011). Impact of Cr-poisoning on the conductivity of LaNi0.6Fe0.4O3. Journal of power sources, 196(22), 9290-9298. https://doi.org/10.1016/j.jpowsour.2011.07.070