skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: 2:1 Charge disproportionation in perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+}

Abstract

La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} was synthesized at a high pressure and high temperature. The compound crystallizes in a √2a×2a×√2a perovskite cell in which the La and Ca ions at the A site are disordered. At 217 K the Fe{sup 3.67+} shows charge disproportionation to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1, and this disproportionation is accompanied by transitions in magnetic and transport properties. The charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. The local electronic and magnetic environments of Fe in La{sub 1/3}Ca{sub 2/3}FeO{sub 3} are quite similar to those of Fe in La{sub 1/3}Sr{sub 2/3}FeO{sub 3}, and the 2:1 charge disproportionation pattern of Fe{sup 3+} and Fe{sup 5+} in La{sub 1/3}Ca{sub 2/3}FeO{sub 3} is also the same as that in La{sub 1/3}Sr{sub 2/3}FeO{sub 3}. - Graphical abstract: The perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} shows charge disproportionation to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1, and the charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. - Highlights: • La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} wasmore » synthesized at a high pressure and high temperature. • At 217 K the Fe{sup 3.67+} shows charge disproportionation (CD) to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1. • The charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. • The disproportionation is accompanied by transitions in magnetic and transport properties.« less

Authors:
; ; ; ;  [1];  [1];  [2]
  1. Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan)
  2. (Japan)
Publication Date:
OSTI Identifier:
22658184
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 246; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CALCIUM COMPOUNDS; CALCIUM IONS; IRON IONS; LANTHANUM COMPOUNDS; OXIDATION; OXIDES; PEROVSKITE; PRESSURE RANGE MEGA PA 10-100; REDUCTION; TEMPERATURE RANGE 0065-0273 K; TEMPERATURE RANGE 0400-1000 K

Citation Formats

Guo, Haichuan, Hosaka, Yoshiteru, Seki, Hayato, Saito, Takashi, Ichikawa, Noriya, Shimakawa, Yuichi, E-mail: shimak@scl.kyoto-u.ac.jp, and Integrated Research Consortium on Chemical Sciences, Uji, Kyoto 611-0011. 2:1 Charge disproportionation in perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+}. United States: N. p., 2017. Web. doi:10.1016/J.JSSC.2016.11.027.
Guo, Haichuan, Hosaka, Yoshiteru, Seki, Hayato, Saito, Takashi, Ichikawa, Noriya, Shimakawa, Yuichi, E-mail: shimak@scl.kyoto-u.ac.jp, & Integrated Research Consortium on Chemical Sciences, Uji, Kyoto 611-0011. 2:1 Charge disproportionation in perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+}. United States. doi:10.1016/J.JSSC.2016.11.027.
Guo, Haichuan, Hosaka, Yoshiteru, Seki, Hayato, Saito, Takashi, Ichikawa, Noriya, Shimakawa, Yuichi, E-mail: shimak@scl.kyoto-u.ac.jp, and Integrated Research Consortium on Chemical Sciences, Uji, Kyoto 611-0011. Wed . "2:1 Charge disproportionation in perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+}". United States. doi:10.1016/J.JSSC.2016.11.027.
@article{osti_22658184,
title = {2:1 Charge disproportionation in perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+}},
author = {Guo, Haichuan and Hosaka, Yoshiteru and Seki, Hayato and Saito, Takashi and Ichikawa, Noriya and Shimakawa, Yuichi, E-mail: shimak@scl.kyoto-u.ac.jp and Integrated Research Consortium on Chemical Sciences, Uji, Kyoto 611-0011},
abstractNote = {La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} was synthesized at a high pressure and high temperature. The compound crystallizes in a √2a×2a×√2a perovskite cell in which the La and Ca ions at the A site are disordered. At 217 K the Fe{sup 3.67+} shows charge disproportionation to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1, and this disproportionation is accompanied by transitions in magnetic and transport properties. The charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. The local electronic and magnetic environments of Fe in La{sub 1/3}Ca{sub 2/3}FeO{sub 3} are quite similar to those of Fe in La{sub 1/3}Sr{sub 2/3}FeO{sub 3}, and the 2:1 charge disproportionation pattern of Fe{sup 3+} and Fe{sup 5+} in La{sub 1/3}Ca{sub 2/3}FeO{sub 3} is also the same as that in La{sub 1/3}Sr{sub 2/3}FeO{sub 3}. - Graphical abstract: The perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} shows charge disproportionation to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1, and the charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. - Highlights: • La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} was synthesized at a high pressure and high temperature. • At 217 K the Fe{sup 3.67+} shows charge disproportionation (CD) to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1. • The charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. • The disproportionation is accompanied by transitions in magnetic and transport properties.},
doi = {10.1016/J.JSSC.2016.11.027},
journal = {Journal of Solid State Chemistry},
number = ,
volume = 246,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2017},
month = {Wed Feb 15 00:00:00 EST 2017}
}
  • 3d metal K-shell X-ray absorption spectra of perovskites with the composition La{sub 1-x}Ca{sub x}CoO{sub 3-{delta}} (x=0, 0.2, 0.4, 0.5, 0.6, 0.8), La{sub 1-x}Sr{sub x}CoO{sub 3-{delta}} (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) and La{sub 1-x}Sr{sub x}FeO{sub 3-{delta}} (x=0, 0.2, 0.4, 0.5, 0.6, 0.8) are compared on the basis of pre-edges, white line features and extended fine structures. The measurements were performed at 300 K and for La{sub 1-x}Ca{sub x}CoO{sub 3-{delta}} also at temperatures as low as 10-20 K. Going to low-temperature the measurements indicate an increase in t{sub 2g}{sup Low-Asterisk} and a decrease in e{sub g}{sup Low-Asterisk} orbital occupancy, which ismore » most accentuated in the LaCoO{sub 3} sample. Virtually no Co K-edge shift was observed for the La{sub 1-x}Ca{sub x}CoO{sub 3-{delta}} and La{sub 1-x}Sr{sub x}CoO{sub 3-{delta}} compounds and the Co-O distances are also not significantly reduced when La{sup 3+} is partially substituted by Ca{sup 2+} or Sr{sup 2+}. From the pre-edge features of these perovskites we are tended to conclude that the t{sub 2g}{sup Low-Asterisk} orbitals are less, and the e{sub g}{sup Low-Asterisk} orbitals are more occupied with increasing x in the Ca and Sr substituted compounds, whereas the total d-electron density is not changing. These results indicate that cobalt prefers a valence state of 3{sup +} in these Co perovskites. This could also be confirmed with iodometric titrations. The Fe perovskites behave differently. In contrast to the Co perovskites, for La{sub 1-x}Sr{sub x}FeO{sub 3-{delta}} perovskites the Fe K-edge is shifted, the pre-edge features intensity is increasing and the Fe-O bond length is decreasing with increasing x. The valence states of the iron in the La{sub 1-x}Sr{sub x}FeO{sub 3-{delta}} perovskites in fact increase as much as x increases. - Graphical abstract: Co K and Fe K pre-edge of La{sub 1-x}Ca{sub x}CoO{sub 3-{delta}} and La{sub 1-x}Sr{sub x}FeO{sub 3-{delta}} perovskites one of the evidences in favor of {delta}=x/2 for the Co-perovskites and {delta}=0 for the Fe-perovskites. Highlights: Black-Right-Pointing-Pointer XAS a valuable tool to evaluate the valence states of Co and Fe perovskites. Black-Right-Pointing-Pointer For La{sub 1-x}Ca{sub x}CoO{sub 3-{delta}} and La{sub 1-x}Sr{sub x}CoO{sub 3-{delta}} perovskites {delta} is close to x/2. Black-Right-Pointing-Pointer For La{sub 1-x}Sr{sub x}FeO{sub 3-{delta}} series {delta} is close to 0. Black-Right-Pointing-Pointer Discussion of the x dependency of the pre-edge bands.« less
  • The nature of charge disproportionation in orthorhombic lanthanum orthoferrites La{sub 1-x}Ca{sub x}FeO{sub 3-δ} (x = 0.4 and 0.5) has been investigated by kilohertz mechanical spectroscopy. Contrast to rhombohedral La{sub 1-x}Sr{sub x}FeO{sub 3-δ} (x = 0.5), no elastic softening was observed in La{sub 1-x}Ca{sub x}FeO{sub 3-δ} above charge disproportionation. This different behavior of elastic modulus in La{sub 1-x}Ca{sub x}FeO{sub 3-δ} and La{sub 1-x}Sr{sub x}FeO{sub 3-δ} unveils the implicit orbital effect. Below charge disproportionation, an internal friction peak around 140 K was observed in La{sub 1-x}Ca{sub x}FeO{sub 3-δ}, which is similar to that in La{sub 1-x}Sr{sub x}FeO{sub 3-δ}. This peak is ascribed to an elastic manifestation ofmore » charge freezing and can be used as an indirect indication of CD in doped LaFeO{sub 3}.« less
  • The highly Mn{sup +4}-doped compound La{sub 0.35}Ca{sub 0.65}MnO{sub 3} has been studied up to high temperature (700 K) by using thermal-expansion, magnetostriction, magnetoresistance, and neutron-diffraction techniques. From 700 K down to room temperature the electrical conduction takes place through thermally activated hopping of polarons with E{sub hop}=45 meV. At the charge-ordering (CO) transition temperature T{sub CO}=275 K, pronounced anomalies in the resistivity and the lattice are observed. The neutron thermodiffractogram clearly establishes that the CO state occurs in the paramagnetic (P) phase and is accompanied by a large anisotropic lattice distortion with a simultaneous large distortion of the MnO{sub 6}more » octahedra. The antiferromagnetic (AF) phase appears at T{sub N}=160{plus_minus}3 K. At this temperature no lattice effect is observed. The CO-P and the CO-AF ground states are stable under an applied magnetic field up to 12 T. thinsp {copyright} {ital 1997} {ital The American Physical Society}« less
  • A series of layered perovskite oxides of the formula K[sub 1[minus]x]La[sub x]Ca[sub 2[minus]x]Nb[sub 3]O[sub 10] for 0 < x [le] 1.0 have been prepared. All the members are isostructural, possessing the structure of KCa[sub 2]Nb[sub 3]O[sub 10]. The interlayer potassium ions in the new series can be ion-exchanged with protons to give H[sub 1[minus]x]La[sub x]Ca[sub 2[minus]x]Nb[sub 3]O[sub 10]. The latter readily forms intercalation compounds of the formula (C[sub n]H[sub 2n+1]NH[sub 3])[sub 1[minus]x]La[sub x]Ca[sub 2[minus]x]Nb[sub 3]O[sub 10], just as the parent solid acid HCa[sub 2]Nb[sub 3]O[sub 10]. The end member LaCaNb[sub 3]O[sub 10] containing no interlayer cations is a nove layeredmore » perovskite oxide, being a n = 3 member of the series A[sub n[minus]1]B[sub n]X[sub 3n+1]. 16 refs., 5 figs., 5 tabs.« less