Publication
Title
Transmission electron microscopy study of $BA_{0.5}Sr_{0.5}CO_{0.8}Fe_{0.2}O_{3-\delta}$ Perovskite decomposition at intermediate temperatures
Author
Abstract
 The cubic perovskite Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-delta) (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 Ba(0.5)Sr(0.5)CoO(3-delta) , the formation of lamellar noncubic phases was observed in the quenched samples. The structure of the lamellae with the previously unknown composition Ba(1-x)Sr(x)Co(2-y)Fe(y)O(5-delta) 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.
Language
English
Source (journal)
Chemistry of materials / American Chemical Society. - Washington, D.C.
Publication
Washington, D.C. : 2010
ISSN
0897-4756
Volume/pages
22:21(2010), p. 5866-5875
ISI
000283623700010
Full text (Publisher's DOI)
UAntwerpen
 Faculty/Department Research group Publication type Subject Affiliation Publications with a UAntwerp address