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Temperature‐Induced Intersite Charge Transfer Involving Cr ions in A‐Site‐Ordered Perovskites ACu 3 Cr 4 O 12 (A=La and Y)
Author(s) -
Zhang Shoubao,
Saito Takashi,
Mizumaki Masaichiro,
Shimakawa Yuichi
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201403692
Subject(s) - valence (chemistry) , octahedron , ion , transition metal , crystallography , chemistry , metal , perovskite (structure) , materials science , crystal structure , catalysis , biochemistry , organic chemistry
Changes in the valence state of transition‐metal ions in oxides drastically modify the chemical and physical properties of the compounds. Intersite charge transfer (ISCT), which involves simultaneous changes in the valence states of two valence‐variable transition‐metal cations at different crystallographic sites, further expands opportunities to show multifunctional properties. To explore new ISCT materials, we focus on A‐site‐ordered perovskite‐structure oxides with the chemical formula AA′ 3 B 4 O 12 , which contain different transition‐metal cations at the square‐planar A′ and octahedral B sites. We have obtained new A‐site‐ordered perovskites LaCu 3 Cr 4 O 12 and YCu 3 Cr 4 O 12 by synthesis under high‐pressure and high‐temperature conditions and found that they showed temperature‐induced ISCT between A′‐site Cu and B‐site Cr ions. The compounds are the first examples of those, in which Cr ions are involved in temperature‐induced ISCT. In contrast to the previously reported ISCT compounds, LaCu 3 Cr 4 O 12 and YCu 3 Cr 4 O 12 showed positive‐thermal‐expansion‐like volume changes at the ISCT transition.