TY - JOUR
T1 - Sr Segregation in Perovskite Oxides
T2 - Why It Happens and How It Exists
AU - Koo, Bonjae
AU - Kim, Kyeounghak
AU - Kim, Jun Kyu
AU - Kwon, Hyunguk
AU - Han, Jeong Woo
AU - Jung, Woo Chul
N1 - Publisher Copyright:
© 2018 Elsevier Inc.
PY - 2018/8/15
Y1 - 2018/8/15
N2 - Among the phenomena related to the surface rearrangement of cations in perovskite-based oxides, A-site cation enrichment, Sr in particular, near the surface has been frequently observed. Upon annealing in an oxidizing atmosphere, Sr is often enriched on the surface as compared with the bulk composition of the material, which eventually forms Sr-rich phases or rearranges the crystal structure of the surface. This Sr segregation changes the structure and composition of the perovskite surfaces and thus affects the stability of the materials and the reactivity with gas phases. In this regard, many studies have been carried out in the field of solid oxide electrochemical cells (SOCs). In this review, we summarize the latest research efforts on Sr segregation in perovskite-based SOC O2 electrodes, with a focus on how excess Sr is present. We then discuss the origins of Sr segregation and suggest strategies for suppressing it to realize high-performance perovskite-based O2 electrodes. Solid oxide electrochemical cells (SOCs) are a promising energy storage/conversion device that can store energy in the form of chemical fuels (electrolysis mode) or convert fuel to electricity (fuel-cell mode) with a remarkably high efficiency. A challenge to SOC development is the degradation of perovskite-based O2 electrodes, primarily due to Sr segregation on the electrode surfaces at high operating temperatures. Despite many efforts, practical solutions have not yet been proposed to inhibit Sr segregation. In this review, we classify recent discoveries of formations and structures of Sr segregation on perovskite surfaces, which allow us to clarify what Sr segregation is. We then reinterpret the research findings reported thus far to elucidate microscopic and macroscopic aspects of the segregation driving forces. The insights from this discussion present strategies to control Sr segregation and suggest new directions to be taken in the future to design the ideal O2 electrode. In this review, we summarize the latest research efforts on surface Sr segregation in perovskite-based O2 electrodes for solid oxide electrochemical cells, with a focus on how excess Sr is caused. The major driving forces of the segregation are elucidated in both microscopic and macroscopic aspects. The insights from this discussion allow us to present strategies to control Sr segregation and to suggest new directions to be taken in the future to design the ideal O2 electrode.
AB - Among the phenomena related to the surface rearrangement of cations in perovskite-based oxides, A-site cation enrichment, Sr in particular, near the surface has been frequently observed. Upon annealing in an oxidizing atmosphere, Sr is often enriched on the surface as compared with the bulk composition of the material, which eventually forms Sr-rich phases or rearranges the crystal structure of the surface. This Sr segregation changes the structure and composition of the perovskite surfaces and thus affects the stability of the materials and the reactivity with gas phases. In this regard, many studies have been carried out in the field of solid oxide electrochemical cells (SOCs). In this review, we summarize the latest research efforts on Sr segregation in perovskite-based SOC O2 electrodes, with a focus on how excess Sr is present. We then discuss the origins of Sr segregation and suggest strategies for suppressing it to realize high-performance perovskite-based O2 electrodes. Solid oxide electrochemical cells (SOCs) are a promising energy storage/conversion device that can store energy in the form of chemical fuels (electrolysis mode) or convert fuel to electricity (fuel-cell mode) with a remarkably high efficiency. A challenge to SOC development is the degradation of perovskite-based O2 electrodes, primarily due to Sr segregation on the electrode surfaces at high operating temperatures. Despite many efforts, practical solutions have not yet been proposed to inhibit Sr segregation. In this review, we classify recent discoveries of formations and structures of Sr segregation on perovskite surfaces, which allow us to clarify what Sr segregation is. We then reinterpret the research findings reported thus far to elucidate microscopic and macroscopic aspects of the segregation driving forces. The insights from this discussion present strategies to control Sr segregation and suggest new directions to be taken in the future to design the ideal O2 electrode. In this review, we summarize the latest research efforts on surface Sr segregation in perovskite-based O2 electrodes for solid oxide electrochemical cells, with a focus on how excess Sr is caused. The major driving forces of the segregation are elucidated in both microscopic and macroscopic aspects. The insights from this discussion allow us to present strategies to control Sr segregation and to suggest new directions to be taken in the future to design the ideal O2 electrode.
KW - O electrode
KW - Sr segregation
KW - perovskite oxide
KW - solid oxide electrochemical cells
KW - solid oxide fuel cells
UR - https://www.scopus.com/pages/publications/85053830021
U2 - 10.1016/j.joule.2018.07.016
DO - 10.1016/j.joule.2018.07.016
M3 - Review article
AN - SCOPUS:85053830021
SN - 2542-4351
VL - 2
SP - 1476
EP - 1499
JO - Joule
JF - Joule
IS - 8
ER -
