Jump to main content
Jump to site search

Issue 17, 2016
Previous Article Next Article

Density functional theory + U analysis of the electronic structure and defect chemistry of LSCF (La0.5Sr0.5Co0.25Fe0.75O3−δ)

Author affiliations

Abstract

Reducing operating temperatures is a key step in making solid oxide fuel cell (SOFC) technology viable. A promising strategy for accomplishing this goal is employing mixed ion–electron conducting (MIEC) cathodes. La1−xSrxCo1−yFeyO3−δ (LSCF) is the most widely employed MIEC cathode material; however, rational optimization of the composition of LSCF requires fundamental insight linking its electronic structure to its defect chemistry. To provide the necessary insight, density functional theory plus U (DFT+U) calculations are used to investigate the electronic structure of LSCF (xSr = 0.50, yCo = 0.25). The DFT+U calculations show that LSCF has a significantly different electronic structure than La1−xSrxFeO3 because of the addition of cobalt, but that minimal electronic structure differences exist between La0.5Sr0.5Co0.25Fe0.75O3 and La0.5Sr0.5Co0.5Fe0.5O3. The oxygen vacancy Image ID:c6cp01720g-t3.gif formation energy (ΔEf,vac) is calculated for Image ID:c6cp01720g-t4.gif residing in different local environments within La0.5Sr0.5Co0.25Fe0.75O3. These results show that Image ID:c6cp01720g-t5.gif configurations have the highest ΔEf,vac, while Image ID:c6cp01720g-t6.gif have the lowest ΔEf,vac and may act as traps for Image ID:c6cp01720g-t7.gif. We conclude that compositions with more Fe than Co are preferred because the additional Image ID:c6cp01720g-t8.gif sites would lead to higher overall ΔEf,vac (and lower Image ID:c6cp01720g-t9.gif concentrations), while the trapping strength of the Image ID:c6cp01720g-t10.gif sites is relatively weak (∼0.3 eV).

Graphical abstract: Density functional theory + U analysis of the electronic structure and defect chemistry of LSCF (La0.5Sr0.5Co0.25Fe0.75O3−δ)

Back to tab navigation

Supplementary files

Article information


Submitted
14 Mar 2016
Accepted
05 Apr 2016
First published
06 Apr 2016

Phys. Chem. Chem. Phys., 2016,18, 12260-12269
Article type
Paper

Density functional theory + U analysis of the electronic structure and defect chemistry of LSCF (La0.5Sr0.5Co0.25Fe0.75O3−δ)

A. M. Ritzmann, J. M. Dieterich and E. A. Carter, Phys. Chem. Chem. Phys., 2016, 18, 12260
DOI: 10.1039/C6CP01720G

Social activity

Search articles by author

Spotlight

Advertisements