First-Principles Study of Lanthanum Strontium Manganite: Insights into Electronic Structure and Oxygen Vacancy Formation

被引:82
作者
Pavone, Michele [1 ]
Munoz-Garcia, Ana B. [1 ]
Ritzmann, Andrew M. [2 ]
Carter, Emily A. [3 ,4 ]
机构
[1] Univ Naples Federico II, Dept Chem Sci, I-80126 Naples, Italy
[2] Princeton Univ, Dept Chem & Biol Engn, Princeton, NJ 08544 USA
[3] Princeton Univ, Program Computat & Appl Math, Dept Mech & Aerosp Engn, Princeton, NJ 08544 USA
[4] Princeton Univ, Andlinger Ctr Energy & Environm, Princeton, NJ 08544 USA
关键词
TOTAL-ENERGY CALCULATIONS; AB-INITIO; THIN-FILMS; DEFECT CHEMISTRY; OXIDE; REDUCTION; SR2FE1.5MO0.5O6-DELTA; CONDUCTIVITY; PERFORMANCE; PRINCIPLES;
D O I
10.1021/jp500352h
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We characterize the structural, electronic, and defect behavior of La1-xSrxMnO3 (LSM) (x(sr) = 0.0, 0.25, and 0.5) by means of density functional theory + U (DFT+U) and hybrid DFT methods. Aliovalent substitution of Sr2+ for La3+ induces formation of holes in the LSM electronic structure. These holes affect electron and oxide ion transport, two key processes occurring within LSM when used as a solid oxide fuel cell (SOFC) cathode. To improve fundamental understanding of these processes, we investigated the atomic-scale effects of increasing Sr content and two different Mn magnetic moment alignments. In agreement with low-temperature experiments, we find a metallic, ferromagnetic (FM) electronic ground state with holes delocalized across the Mn and O sublattices. We also employ an antiferromagnetic (AFM) arrangement of Mn ions to model LSM's high-temperature paramagnetic state. In contrast to FM LSM, the holes in AFM LSM localize to form Mn4+ ions, consistent with the observed high-temperature polaronic transport in LSM. The formation of oxygen vacancies governs oxide ion transport in bulk LSM. We find that the ease with which oxygen vacancies form is strongly influenced by the Sr content and the overall magnetic arrangement of Mn ions. These atomic-scale insights enable us to propose new guidelines for enhanced nanoscale LSM-based SOFC cathodes.
引用
收藏
页码:13346 / 13356
页数:11
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