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Atomic Resolution Analysis of the Defect Chemistry and Microdomain Structure of Brownmillerite‐Type Strontium Cobaltite
Author(s) -
Ito Yasuo,
Klie Robert F.,
Browning Nigel D.,
Mazanec Terry J.
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.tb00201.x
Subject(s) - brownmillerite , cobaltite , valence (chemistry) , chemistry , crystallography , octahedron , crystal chemistry , oxygen , crystal structure , perovskite (structure) , organic chemistry
To investigate the fundamental aspects of vacancy ordering in oxygen‐transporting ceramic membranes, we have performed atomic resolution analysis of individual domains in brownmillerite‐type SrCoO 3−δ . Electron energy loss spectroscopy indicates that the Co valence state in adjacent planes can be 2+ and 4+. This charge localization is accompanied by oxygen deficiency and the formation of ordered octahedral and tetrahedral coordinated Co sites. At microdomain boundaries, Z ‐contrast images reveal a structural relaxation of the octahedral site with the reduction of the Co valence state from 4+ to 3+ and the incorporation of extra oxygen vacancies.