title: Cationic Intermixing and Reactivity at the La2 Mo2 O9 /La0.8 Sr0.2 MnO3-δ Solid Oxide Fuel Cell Electrolyte-Cathode Interface.
abstract: Among standard high-temperature cathode materials for solid oxide fuel cells, La0.8 Sr0.2 MnO3-δ (LSM) displays the least reactivity with the oxide-ion conductor La2 Mo2 O9 (LMO), yet a reaction is observed at high processing temperatures, identified by using XRD and focused ion beam secondary-ion mass spectrometry (FIB-SIMS) after annealing at 1050 and 1150 °C. Additionally, Sr and Mn solutions were deposited and annealed on LMO pellets, as well as a Mo solution on a LSM pellet. From these studies several reaction products were identified by using XRD and located by using FIB-SIMS on the surface of pelletised samples. We used depth profiling to show that the reactivity extended up to ∼10 μm from the surface region. If Sr was present, a SrMoO4 -type scheelite phase was always observed as a reaction product, and if Mn was present, LaMnO3+δ single crystals were observed on the surface of the LMO pellets. Additional phases such as La2 MoO6 and La6 MoO12 were also detected depending on the configuration and annealing temperature. Reaction mechanisms and detailed reaction formulae are proposed to explain these observations. The strongest driving force for cationic diffusion appears to originate from Mo(6+) and Mn(3+) cations, rather than from Sr(2+) .
authors.affiliation: Institut des Molécules et Matériaux du Mans (IMMM), Univ. Bretagne-Loire, UMR CNRS 6283, Univ. Maine, avenue Olivier Messiaen, F-72085, Le Mans cedex 9, France.
authors.forename: Uday K
authors.initials: UK
authors.lastname: Ravella
authors.affiliation: Department of Materials, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Liu
authors.affiliation: Institut des Molécules et Matériaux du Mans (IMMM), Univ. Bretagne-Loire, UMR CNRS 6283, Univ. Maine, avenue Olivier Messiaen, F-72085, Le Mans cedex 9, France.
authors.forename: Gwenaël
authors.initials: G
authors.lastname: Corbel
authors.affiliation: Department of Materials, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. s.skinner@imperial.ac.uk.
authors.forename: Stephen J
authors.identifier: 0000-0001-5446-2647
authors.initials: SJ
authors.lastname: Skinner
authors.affiliation: Institut des Molécules et Matériaux du Mans (IMMM), Univ. Bretagne-Loire, UMR CNRS 6283, Univ. Maine, avenue Olivier Messiaen, F-72085, Le Mans cedex 9, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Lacorre
mesh_terms: D004058:Diffusion; D011211:Electric Power Supplies; D004566:Electrodes; D004573:Electrolytes / Q000737:chemistry; D007811:Lanthanum / Q000737:chemistry; D008345:Manganese / Q000737:chemistry; D008982:Molybdenum / Q000737:chemistry; D010087:Oxides / Q000737:chemistry*; D013324:Strontium / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature
chemical_list: D004573:Electrolytes; D010087:Oxides; D008345:Manganese; D007811:Lanthanum; D008982:Molybdenum; D013324:Strontium
keywords: fuel cells; manganese; mass spectrometry; strontium; x-ray diffraction