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Charge Disproportionation and Charge Transfer in A ‐site Ordered Perovskites Containing Iron
Author(s) -
Shimakawa Yuichi,
Takano Mikio
Publication year - 2009
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200900248
Subject(s) - disproportionation , valence (chemistry) , charge (physics) , ion , perovskite (structure) , materials science , charge ordering , chemistry , crystallography , inorganic chemistry , analytical chemistry (journal) , catalysis , physics , biochemistry , organic chemistry , quantum mechanics , chromatography
New A ‐site ordered perovskite structure oxides, CaCu 3 Fe 4 O 12 and LaCu 3 Fe 4 O 12 , were synthesized under high‐pressure and high‐temperature conditions. The compounds contain unusually high valence states of iron: Fe 4+ in CaCu 3 Fe 4 O 12 and Fe 3.75+ in LaCu 3 Fe 4 O 12 . Instabilities of the high oxidation states at low temperatures are resolved in CaCu 3 Fe 4 O 12 by charge disproportionation from Fe 4+ to Fe 3+ and Fe 5+ and in LaCu 3 Fe 4 O 12 by charge transfer between A ‐site copper and B ‐site iron ions. The charge disproportionation and the charge transfer are accompanied by significant changes in structural, transport, and magnetic properties.