Affiliation:
1. Physical and Computational Sciences Directorate Pacific Northwest National Laboratory Richland WA 99352 USA
2. Energy and Environment Directorate Pacific Northwest National Laboratory Richland WA 99352 USA
3. Department of Physics University of Washington Seattle WA 98195 USA
Abstract
AbstractPerovskite structured transition metal oxides are important technological materials for catalysis and solid oxide fuel cell applications. Their functionality often depends on oxygen diffusivity and mobility through complex oxide heterostructures, which can be significantly impacted by structural and chemical modifications, such as doping. Further, when utilized within electrochemical cells, interfacial reactions with other components (e.g., Ni‐ and Cr‐based alloy electrodes and interconnects) can influence the perovskite's reactivity and ion transport, leading to complex dependencies that are difficult to control in real‐world environments. Here, this work uses isotopic tracers and atom probe tomography to directly visualize oxygen diffusion and transport pathways across perovskite and metal‐perovskite heterostructures, that is, (Ni‐Cr coated) Sr‐doped lanthanum ferrite (La0.5Sr0.5FeO3; LSFO). Annealing in 18O2(g) results in elemental and isotopic redistributions through oxygen exchange (OE) in the LSFO while Ni‐Cr undergoes oxidation via multiple mechanisms and transport pathways. Complementary density functional theory calculations at experimental conditions provide rationale for OE reaction mechanisms and reveal a complex interplay of different thermodynamic and kinetic drivers. These results shed light on the fundamental coupling of defects and oxygen transport in an important class of catalytic materials.
Funder
U.S. Department of Energy
Basic Energy Sciences
Subject
Mechanical Engineering,Mechanics of Materials
Cited by
2 articles.
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