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Study of the Mixed‐Conducting SrFeCo 0.5 O y System
Author(s) -
Ma Beihai,
Victory Nicole I.,
Balachandran U.,
Mitchell Brian J.,
Richardson J. W.
Publication year - 2002
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2002.tb00508.x
Subject(s) - brownmillerite , perovskite (structure) , oxygen , phase (matter) , syngas , analytical chemistry (journal) , methane , materials science , oxygen permeability , ceramic , partial pressure , conductivity , neutron diffraction , mineralogy , chemistry , crystallography , crystal structure , catalysis , metallurgy , chromatography , biochemistry , organic chemistry
Mixed‐conducting Sr‐Fe‐Co oxides have potential applications in dense ceramic membranes for high‐purity oxygen separation and/or methane conversion to produce syngas (CO + H 2 ), because of their combined high electronic/ionic conductivity and significant oxygen permeability. SrFeCo 0.5 O y has been synthesized by the solid‐state reaction method. Conductivities were measured at elevated temperatures in various gas environments and increased as temperature and oxygen partial pressure ( p O2 ) increased in the surrounding environment. Neutron powder diffraction experiments revealed that in a high p O2 environment the SrFeCo 0.5 O y material consists of three different phases. The relative concentration of each component phase is dependent on temperature and p O2 in the surrounding environment. In air, Sr 2 (Fe, Co) 3 O y (236‐phase) is the majority phase and consists of >75 wt% of the total, whereas the perovskite and rocksalt phases account for ∼20 and <5 wt%, respectively. However, in a reducing environment, the 236‐phase decomposes and converts to perovskite and rocksalt phase at high temperature. In an environment of p O2 < 10 −12.2 atm, the 236‐phase is completely converted into perovskite (brownmillerite) and rocksalt phases.