Charge disproportionation in (X0.6Sr0.4)0.99Fe0.8Co0.2O3-δ perovskites (X = La, Pr, Sm, Gd)

Thomas Pedersen; Souheil Saadi; K.H. Nielsen; Steen Mørup; Kent Kammer Hansen

doi:10.1016/j.ssi.2005.04.003

Charge disproportionation in (X₀_.₆Sr₀_.₄)₀_.₉₉Fe₀_.₈Co₀_.₂O₃_-δ perovskites (X = La, Pr, Sm, Gd)

Thomas Pedersen, Souheil Saadi, K.H. Nielsen, Steen Mørup, Kent Kammer Hansen

Department of Physics

Technical University of Denmark

Research output: Contribution to journal › Journal article › Research › peer-review

Abstract

The change in crystal structure and the oxidation state in iron of iron-cobalt-based perovskites with different A-site cations is investigated by the use of powder XRD and Mossbauer spectroscopy. The perovskites investigated are (X0.6Sr0.4)(0.99)Fe0.8Co0.2O3-delta, where X is La, Pr, Sm or Gd. It is shown that the crystal structure changes from hexagonal to orthorhombic when the size of the A-site cation is lowered. At room temperature, the oxidation state of iron increases when the size of the A-site cation is lowered. This is explained by a crystal packing effect. At lower temperatures, charge disproportionation of Fe(IV) occurs to Fe(III) and Fe(V). The transition temperature depends on the type of the A-site cation. Some of the Fe is reduced to Fe(III) by transference of electrons from Co upon cooling below room temperature.

Original language	English
Journal	Solid State Ionics
Volume	176
Issue number	17-18
Pages (from-to)	1555-1561
ISSN	0167-2738
DOIs	https://doi.org/10.1016/j.ssi.2005.04.003
Publication status	Published - 2005

Keywords

Perovskites
Charge disproportionation
Mossbauer spectroscopy

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10.1016/j.ssi.2005.04.003

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@article{84e40ccd308346e58de15b7a64edc56d,

title = "Charge disproportionation in (X0.6Sr0.4)0.99Fe0.8Co0.2O3-δ perovskites (X = La, Pr, Sm, Gd)",

abstract = "The change in crystal structure and the oxidation state in iron of iron-cobalt-based perovskites with different A-site cations is investigated by the use of powder XRD and Mossbauer spectroscopy. The perovskites investigated are (X0.6Sr0.4)(0.99)Fe0.8Co0.2O3-delta, where X is La, Pr, Sm or Gd. It is shown that the crystal structure changes from hexagonal to orthorhombic when the size of the A-site cation is lowered. At room temperature, the oxidation state of iron increases when the size of the A-site cation is lowered. This is explained by a crystal packing effect. At lower temperatures, charge disproportionation of Fe(IV) occurs to Fe(III) and Fe(V). The transition temperature depends on the type of the A-site cation. Some of the Fe is reduced to Fe(III) by transference of electrons from Co upon cooling below room temperature.",

keywords = "Perovskites, Charge disproportionation, Mossbauer spectroscopy",

author = "Thomas Pedersen and Souheil Saadi and K.H. Nielsen and Steen M{\o}rup and {Kammer Hansen}, Kent",

year = "2005",

doi = "10.1016/j.ssi.2005.04.003",

language = "English",

volume = "176",

pages = "1555--1561",

journal = "Solid State Ionics",

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TY - JOUR

T1 - Charge disproportionation in (X0.6Sr0.4)0.99Fe0.8Co0.2O3-δ perovskites (X = La, Pr, Sm, Gd)

AU - Pedersen, Thomas

AU - Saadi, Souheil

AU - Nielsen, K.H.

AU - Mørup, Steen

AU - Kammer Hansen, Kent

PY - 2005

Y1 - 2005

N2 - The change in crystal structure and the oxidation state in iron of iron-cobalt-based perovskites with different A-site cations is investigated by the use of powder XRD and Mossbauer spectroscopy. The perovskites investigated are (X0.6Sr0.4)(0.99)Fe0.8Co0.2O3-delta, where X is La, Pr, Sm or Gd. It is shown that the crystal structure changes from hexagonal to orthorhombic when the size of the A-site cation is lowered. At room temperature, the oxidation state of iron increases when the size of the A-site cation is lowered. This is explained by a crystal packing effect. At lower temperatures, charge disproportionation of Fe(IV) occurs to Fe(III) and Fe(V). The transition temperature depends on the type of the A-site cation. Some of the Fe is reduced to Fe(III) by transference of electrons from Co upon cooling below room temperature.

AB - The change in crystal structure and the oxidation state in iron of iron-cobalt-based perovskites with different A-site cations is investigated by the use of powder XRD and Mossbauer spectroscopy. The perovskites investigated are (X0.6Sr0.4)(0.99)Fe0.8Co0.2O3-delta, where X is La, Pr, Sm or Gd. It is shown that the crystal structure changes from hexagonal to orthorhombic when the size of the A-site cation is lowered. At room temperature, the oxidation state of iron increases when the size of the A-site cation is lowered. This is explained by a crystal packing effect. At lower temperatures, charge disproportionation of Fe(IV) occurs to Fe(III) and Fe(V). The transition temperature depends on the type of the A-site cation. Some of the Fe is reduced to Fe(III) by transference of electrons from Co upon cooling below room temperature.

KW - Perovskites

KW - Charge disproportionation

KW - Mossbauer spectroscopy

U2 - 10.1016/j.ssi.2005.04.003

DO - 10.1016/j.ssi.2005.04.003

M3 - Journal article

SN - 0167-2738

VL - 176

SP - 1555

EP - 1561

JO - Solid State Ionics

JF - Solid State Ionics

IS - 17-18

ER -