Details
| Originalsprache | Englisch |
|---|---|
| Seiten (von - bis) | 5866-5875 |
| Seitenumfang | 10 |
| Fachzeitschrift | Chemistry of Materials |
| Jahrgang | 22 |
| Ausgabenummer | 21 |
| Frühes Online-Datum | 13 Okt. 2010 |
| Publikationsstatus | Veröffentlicht - 9 Nov. 2010 |
Abstract
The cubic perovskite Ba0.5Sr0.5Co 0.8Fe0.2O3-δ (denoted BSCF) is the state-of-the-art ceramic membrane material used for oxygen separation technologies above 1150 K. BSCF is a mixed oxygen-ion and electron conductor (MIEC) and exhibits one of the highest oxygen permeabilities reported so far for dense oxides. Additionally, it has excellent phase stability above 1150 K. In the intermediate temperature range (750-1100 K), however, BSCF suffers from a slow decomposition of the cubic perovskite into variants with hexagonal stacking that are barriers to oxygen transport. To elucidate details of the decomposition process, both sintered BSCF ceramic and powder were annealed for 180-240 h in ambient air at temperatures below 1123 K and analyzed by different transmission electron microscopy techniques. Aside from hexagonal perovskite Ba0.6Sr0.4CoO3-δ, the formation of lamellar noncubic phases was observed in the quenched samples. The structure of the lamellae with the previously unknown composition Ba1-xSr xCo2-yFeyO5-δ was found to be related to the 15R hexagonal perovskite polytype. The valence and spin-state transition of cobalt leading to a considerable diminution of its ionic radius can be considered a reason for BSCF's inherent phase instability at intermediate temperatures.
ASJC Scopus Sachgebiete
- Chemie (insg.)
- Allgemeine Chemie
- Chemische Verfahrenstechnik (insg.)
- Allgemeine chemische Verfahrenstechnik
- Werkstoffwissenschaften (insg.)
- Werkstoffchemie
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in: Chemistry of Materials, Jahrgang 22, Nr. 21, 09.11.2010, S. 5866-5875.
Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Peer-Review
}
TY - JOUR
T1 - Transmission electron microscopy study of Ba0.5Sr 0.5Co0.8Fe0.2O3-δ perovskite decomposition at intermediate temperatures
AU - Efimov, Konstantin
AU - Xu, Qiang
AU - Feldhoff, Armin
PY - 2010/11/9
Y1 - 2010/11/9
N2 - The cubic perovskite Ba0.5Sr0.5Co 0.8Fe0.2O3-δ (denoted BSCF) is the state-of-the-art ceramic membrane material used for oxygen separation technologies above 1150 K. BSCF is a mixed oxygen-ion and electron conductor (MIEC) and exhibits one of the highest oxygen permeabilities reported so far for dense oxides. Additionally, it has excellent phase stability above 1150 K. In the intermediate temperature range (750-1100 K), however, BSCF suffers from a slow decomposition of the cubic perovskite into variants with hexagonal stacking that are barriers to oxygen transport. To elucidate details of the decomposition process, both sintered BSCF ceramic and powder were annealed for 180-240 h in ambient air at temperatures below 1123 K and analyzed by different transmission electron microscopy techniques. Aside from hexagonal perovskite Ba0.6Sr0.4CoO3-δ, the formation of lamellar noncubic phases was observed in the quenched samples. The structure of the lamellae with the previously unknown composition Ba1-xSr xCo2-yFeyO5-δ was found to be related to the 15R hexagonal perovskite polytype. The valence and spin-state transition of cobalt leading to a considerable diminution of its ionic radius can be considered a reason for BSCF's inherent phase instability at intermediate temperatures.
AB - The cubic perovskite Ba0.5Sr0.5Co 0.8Fe0.2O3-δ (denoted BSCF) is the state-of-the-art ceramic membrane material used for oxygen separation technologies above 1150 K. BSCF is a mixed oxygen-ion and electron conductor (MIEC) and exhibits one of the highest oxygen permeabilities reported so far for dense oxides. Additionally, it has excellent phase stability above 1150 K. In the intermediate temperature range (750-1100 K), however, BSCF suffers from a slow decomposition of the cubic perovskite into variants with hexagonal stacking that are barriers to oxygen transport. To elucidate details of the decomposition process, both sintered BSCF ceramic and powder were annealed for 180-240 h in ambient air at temperatures below 1123 K and analyzed by different transmission electron microscopy techniques. Aside from hexagonal perovskite Ba0.6Sr0.4CoO3-δ, the formation of lamellar noncubic phases was observed in the quenched samples. The structure of the lamellae with the previously unknown composition Ba1-xSr xCo2-yFeyO5-δ was found to be related to the 15R hexagonal perovskite polytype. The valence and spin-state transition of cobalt leading to a considerable diminution of its ionic radius can be considered a reason for BSCF's inherent phase instability at intermediate temperatures.
UR - http://www.scopus.com/inward/record.url?scp=78149265805&partnerID=8YFLogxK
U2 - 10.1021/cm101745v
DO - 10.1021/cm101745v
M3 - Article
AN - SCOPUS:78149265805
VL - 22
SP - 5866
EP - 5875
JO - Chemistry of Materials
JF - Chemistry of Materials
SN - 0897-4756
IS - 21
ER -