Density Functional Theory Modeling of A-site Cation Diffusion in Bulk LaMnO3±δ for Solid Oxide Fuel Cell Cathodes. (30th May 2017)

• Record Type: Journal Article
• Authors: Lee, Yueh-Lin; Duan, Yuhua; Morgan, Dane; Sorescu, Dan; Abernathy, Harry; Hackett, Gregory A
• Is Part Of: ECS transactions. Volume 78:Number 1(2017)
• Page Start: 2797
• Page End: 2806
• Publication Date: 2017-05-30
• Subjects: Electrochemistry -- Periodicals; Electrochemistry; Periodicals; Electronic journals; Electronic journal; 541.37
• DOI: 10.1149/07801.2797ecst
• Languages: English
• ISSNs: 1938-5862

Abstract

Abstract : In this work, the diffusion barriers of A-site cation and dopants in bulk LaMnO3±δ (LMO) are determined based on density functional theory (DFT) simulations. These properties are highly relevant for solid oxide fuel cell (SOFC) cathode applications. Due to the weak repulsive interactions (0.2~0.3 eV) between the nearest neighbor A-site and B-site cation vacancies, the A-site and B-site cation vacancy clusters can readily form in LMO. The DFT modeling unveils a facile A-site cation diffusion pathway via a cation vacancy cluster mechanism with a migration barrier reduction of about 1.3 eV versus the direct A-site vacancy migration. By combining these results with the bulk LMO defect modeling, the temperature and oxygen partial pressure dependences of the A-site cation tracer diffusion coefficients are assessed based on the concentration of transport carriers and the migration barriers associated with the A-site cation transport in bulk LMO. The trends in the migration barriers vs. various types of metal cations relevant to SOFC applications i.e. La 3+, Sr 2+, Zr 4+, Y 3+, are also investigated, and the results obtained suggest that both the ionic charge and the ionic radius correlate with the calculated cation migration barriers