title: Suppression of intersite charge transfer in charge-disproportionated perovskite YCu3Fe4O12.
abstract: A novel iron perovskite YCu3Fe4O12 was synthesized under high pressure and high temperature of 15 GPa and 1273 K. Synchrotron X-ray and electron diffraction measurements have demonstrated that this compound crystallizes in the cubic AA'3B4O12-type perovskite structure (space group Im3, No. 204) with a lattice constant of a = 7.30764(10) Å at room temperature. YCu3Fe4O12 exhibits a charge disproportionation of 8Fe(3.75+) → 3Fe(5+) + 5Fe(3+), a ferrimagnetic ordering, and a metal-semiconductor-like transition simultaneously at 250 K, unlike the known isoelectronic compound LaCu3Fe4O12 that currently shows an intersite charge transfer of 3Cu(2+) + 4Fe(3.75+) → 3Cu(3+) + 4Fe(3+), an antiferromagnetic ordering, and a metal-insulator transition at 393 K. This finding suggests that intersite charge transfer is not the only way of relieving the instability of the Fe(3.75+) state in the A(3+)Cu(2+)3Fe(3.75+)4O12 perovskites. Crystal structure analysis reveals that bond strain, rather than the charge account of the A-site alone, which is enhanced by large A(3+) ions, play an important role in determining which of intersite charge transfer or charge disproportionation is practical.
authors.affiliation: Department of Chemistry, Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Hidenobu
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authors.lastname: Etani
authors.forename: Ikuya
authors.initials: I
authors.lastname: Yamada
authors.forename: Kenya
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authors.lastname: Ohgushi
authors.forename: Naoaki
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authors.lastname: Hayashi
authors.forename: Yoshihiro
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authors.lastname: Kusano
authors.forename: Masaichiro
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authors.lastname: Mizumaki
authors.forename: Jungeun
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authors.lastname: Kim
authors.forename: Naruki
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authors.lastname: Tsuji
authors.forename: Ryoji
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authors.lastname: Takahashi
authors.forename: Norimasa
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authors.lastname: Nishiyama
authors.forename: Toru
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authors.lastname: Inoue
authors.forename: Tetsuo
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authors.lastname: Irifune
authors.forename: Mikio
authors.initials: M
authors.lastname: Takano