TY - JOUR
T1 - Suppression of Cation Segregation in (La,Sr)CoO3-δ by Elastic Energy Minimization
AU - Koo, Ja Yang
AU - Kwon, Hyunguk
AU - Ahn, Minwoo
AU - Choi, Mingi
AU - Son, Ji Won
AU - Han, Jeong Woo
AU - Lee, Wonyoung
N1 - Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/3/7
Y1 - 2018/3/7
N2 - Strontium segregation at perovskite surfaces deteriorates the oxygen reduction reaction kinetics of cathodes and therefore the long-term stability of solid oxide fuel cells (SOFCs). For the systematic and quantitative assessment of the elastic energy in perovskite oxides, which is known to be one of the main origins for dopant segregation, we report the fractional free volume as a new descriptor for the elastic energy in the perovskite oxide system. To verify the fractional free volume model, three samples were prepared with different A-site dopants: La0.6Sr0.4CoO3-δ, La0.6Sr0.2Ca0.2CoO3-δ, and La0.6Ca0.4CoO3-δ. A combination of the theoretical calculations of the segregation energy and oxide formation energy and experimental measurements of the structural, chemical, and electrochemical degradation substantiated the validity of using the fractional free volume to predict the dopant segregation. Furthermore, the dopant segregation could be significantly suppressed by increasing the fractional free volume in the perovskite oxides with dopant substitution. Our results provide insight into dopant segregation from the elastic energy perspective and offer a design guideline for SOFC cathodes with enhanced stability at elevated temperatures.
AB - Strontium segregation at perovskite surfaces deteriorates the oxygen reduction reaction kinetics of cathodes and therefore the long-term stability of solid oxide fuel cells (SOFCs). For the systematic and quantitative assessment of the elastic energy in perovskite oxides, which is known to be one of the main origins for dopant segregation, we report the fractional free volume as a new descriptor for the elastic energy in the perovskite oxide system. To verify the fractional free volume model, three samples were prepared with different A-site dopants: La0.6Sr0.4CoO3-δ, La0.6Sr0.2Ca0.2CoO3-δ, and La0.6Ca0.4CoO3-δ. A combination of the theoretical calculations of the segregation energy and oxide formation energy and experimental measurements of the structural, chemical, and electrochemical degradation substantiated the validity of using the fractional free volume to predict the dopant segregation. Furthermore, the dopant segregation could be significantly suppressed by increasing the fractional free volume in the perovskite oxides with dopant substitution. Our results provide insight into dopant segregation from the elastic energy perspective and offer a design guideline for SOFC cathodes with enhanced stability at elevated temperatures.
UR - http://www.scopus.com/inward/record.url?scp=85043342531&partnerID=8YFLogxK
U2 - 10.1021/acsami.7b19390
DO - 10.1021/acsami.7b19390
M3 - Article
C2 - 29443491
AN - SCOPUS:85043342531
SN - 1944-8244
VL - 10
SP - 8057
EP - 8065
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 9
ER -
