Successive Charge Transitions of Unusually High-Valence Fe3.5+: Charge Disproportionation and Intermetallic Charge Transfer.
A perovskite-structure oxide containing unusually high-valence Fe3.5+was obtained by high-pressure synthesis. Instability of the Fe3.5+in Ca0.5Bi0.5FeO3is relieved first by charge disproportionation at 250 K and then by intermetallic charge transfer between A-site Bi and B-site Fe at 200 K. These previously unobserved successive charge transitions are due to competing intermetallic and disproportionation charge instabilities. Both transitions change magnetic and structural properties significantly, indicating strong coupling of charge, spin, and lattice in the present system.
Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
Yoshiteru
Y
Hosaka
Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
Fabio
F
Denis Romero
Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
Noriya
N
Ichikawa
Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
Takashi
T
Saito
Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
Yuichi
Y
Shimakawa
Mössbauer spectroscopy; charge disproportionation; charge transfer; iron; perovskite phases