Ravella Uday K, Liu Jingjing, Corbel Gwenaël, Skinner Stephen J, Lacorre Philippe
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.
Department of Materials, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.
ChemSusChem. 2016 Aug 23;9(16):2182-92. doi: 10.1002/cssc.201600516. Epub 2016 Aug 1.
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+) .
在固体氧化物燃料电池的标准高温阴极材料中，La0.8Sr0.2MnO3-δ（LSM）与氧化物离子导体La2Mo2O9（LMO）的反应活性最低，但在高温处理温度下仍观察到反应，通过在1050和1150°C退火后使用XRD和聚焦离子束二次离子质谱（FIB-SIMS）进行鉴定。此外，将Sr和Mn溶液沉积在LMO颗粒上并进行退火，同时将Mo溶液沉积在LSM颗粒上。通过这些研究，使用XRD鉴定了几种反应产物，并使用FIB-SIMS在造粒样品表面定位。我们使用深度剖析表明，反应活性从表面区域延伸至约10μm。如果存在Sr，总是观察到SrMoO4型白钨矿相作为反应产物，如果存在Mn，则在LMO颗粒表面观察到LaMnO3+δ单晶。根据配置和退火温度，还检测到其他相，如La2MoO6和La6MoO12。提出了反应机理和详细的反应式来解释这些观察结果。阳离子扩散的最强驱动力似乎来自Mo(6+)和Mn(3+)阳离子，而不是来自Sr(2+)。
