Ca2FeMnO6: A Layered Double Perovskite with Unusual High-Valence Fe4+ in a Layered Arrangement

A new double perovskite Ca2FeMnO6 with a layered arrangement of Mn4+ and the unusually high-valence Fe4+ was obtained by oxidizing the precursor brownmillerite Ca2FeMnO5 with ozone at 200 °C. This low-temperature topotactic reaction kept the layered cation arrangement of the brownmillerite but oxidi...

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Bibliographic Details
Published in:Bulletin of the Chemical Society of Japan 2015-05, Vol.88 (5), p.657-661
Main Authors: Hosaka, Yoshiteru, Ichikawa, Noriya, Saito, Takashi, Haruta, Mitsutaka, Kimoto, Koji, Kurata, Hiroki, Shimakawa, Yuichi
Format: Article
Language:English
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Summary:A new double perovskite Ca2FeMnO6 with a layered arrangement of Mn4+ and the unusually high-valence Fe4+ was obtained by oxidizing the precursor brownmillerite Ca2FeMnO5 with ozone at 200 °C. This low-temperature topotactic reaction kept the layered cation arrangement of the brownmillerite but oxidized Mn3+ to Mn4+ and Fe3+ to Fe4+. The crystal structure with a P21/c space group was revealed by detailed structure analysis with neutron powder diffraction data, and the layered arrangement of the cations was confirmed in an STEM-EELS elemental mapping image. The fully oxidized chemical composition was also confirmed by thermogravimetric analysis. Even with the two-dimensional layered arrangement, the instability of the unusually high-valence Fe4+ in Ca2FeMnO6, like that of the Fe4+ in the perovskites CaFeO3 and CaCu3Fe4O12 with three-dimensional arrangements of Fe4+, was relieved by charge disproportionation (2Fe4+ → Fe3+ + Fe5+) at a low temperature.
ISSN:0009-2673
1348-0634
DOI:10.1246/bcsj.20140404