title: Charge-order melting in charge-disproportionated perovskite CeCu3Fe4O12.
abstract: A novel quadruple perovskite oxide CeCu3Fe4O12 has been synthesized under high-pressure and high-temperature conditions of 15 GPa and 1473 K. (57)Fe Mössbauer spectroscopy displays a charge disproportionation transition of 4Fe(3.5+) → 3Fe(3+) + Fe(5+) below ∼270 K, whereas hard X-ray photoemission and soft X-ray absorption spectroscopy measurements confirm that the Ce and Cu valences are retained at approximately +4 and +2, respectively, over the entire temperature range measured. Electron and X-ray diffraction studies reveal that the body-centered cubic symmetry (space group Im3̅, No. 204) is retained at temperatures as low as 100 K, indicating the absence of any types of charge-ordering in the charge-disproportionated CeCu3Fe4O12 phase. The magnetic susceptibility and neutron powder diffraction data illustrate that the antiferromagnetic ordering of Fe ions is predominant in the charge-disproportionated CeCu3Fe4O12 phase. These findings suggest that CeCu3Fe4O12 undergoes a new type of electronic phase in the ACu3Fe4O12 series and that the melting of the charge-ordering in CeCu3Fe4O12 is caused by the substantial decrease in the Fe valence and the resulting large deviation from the ideal abundance ratio of Fe(3+):Fe(5+) = 1:1 for rock-salt-type charge-ordering.
authors.affiliation: Nanoscience and Nanotechnology Research Center, Osaka Prefecture University , 1-2 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8570, Japan.
authors.forename: Ikuya
authors.initials: I
authors.lastname: Yamada
authors.forename: Hidenobu
authors.initials: H
authors.lastname: Etani
authors.forename: Makoto
authors.initials: M
authors.lastname: Murakami
authors.forename: Naoaki
authors.initials: N
authors.lastname: Hayashi
authors.forename: Takateru
authors.initials: T
authors.lastname: Kawakami
authors.forename: Masaichiro
authors.initials: M
authors.lastname: Mizumaki
authors.forename: Shigenori
authors.initials: S
authors.lastname: Ueda
authors.forename: Hideki
authors.initials: H
authors.lastname: Abe
authors.forename: Klaus-Dieter
authors.initials: KD
authors.lastname: Liss
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Studer
authors.forename: Tomoatsu
authors.initials: T
authors.lastname: Ozaki
authors.forename: Shigeo
authors.initials: S
authors.lastname: Mori
authors.forename: Ryoji
authors.initials: R
authors.lastname: Takahashi
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Irifune
mesh_terms: D002563:Cerium / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D005615:Freezing; D058085:Iron Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D010087:Oxides / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D058085:Iron Compounds; D010087:Oxides; D002563:Cerium; D003300:Copper