Spin-state transition of iron in (Ba0.5 Sr0.5) (Fe0.8 Zn0.2) O3 - δ perovskite

Research output: Contribution to journalArticleResearchpeer review

Authors

  • Armin Feldhoff
  • Julia Martynczuk
  • Mirko Arnold
  • Maxym Myndyk
  • Ingo Bergmann
  • Vladimir Šepelák
  • Wolfgang Gruner
  • Ulrich Vogt
  • Angelika Hähnel
  • Jörg Woltersdorf

External Research Organisations

  • Technische Universität Braunschweig
  • Leibniz Institute for Solid State and Materials Research Dresden (IFW)
  • Swiss Federal Laboratories for Material Science and Technology (EMPA)
  • Max Planck Institute of Microstructure Physics
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Details

Original languageEnglish
Pages (from-to)2961-2971
Number of pages11
JournalJournal of solid state chemistry
Volume182
Issue number11
Early online date6 Aug 2009
Publication statusPublished - Nov 2009

Abstract

The redox behavior of iron during heating of a high-performance perovskite for ceramic oxygen separation membranes was studied by combined electron energy-loss (EELS, esp. ELNES) and Mössbauer spectroscopical in situ methods. At room temperature, the iron in (Ba0.5 Sr0.5) (Fe0.8 Zn0.2) O3 - δ (BSFZ) is in a mixed valence state of 75% Fe4 + in the high-spin state and 25% Fe3 + predominantly in the low-spin state. When heated to 900 {ring operator} C, a slight reduction of iron is observed that increases the quantity of Fe3 + species. However, the dominant occurrence is a gradual transition in the spin-state of trivalent iron from a mixed low-spin/high-spin to a pure high-spin configuration. In addition, a remarkable amount of hybridization is found in the Fe-O bonds that are highly polar rather than purely ionic. The coupled valence/spin-state transition correlates with anomalies in thermogravimetry and thermal expansion behavior observed by X-ray diffraction and dilatometry, respectively. Since the effective cationic radii depend not only on the valence but also on the spin-state, both have to be considered when estimating under which conditions a cubic perovskite will tolerate specific cations. It is concluded that an excellent phase stability of perovskite-based membrane materials demands a tailoring, which enables pure high-spin states under operational conditions, even if mixed valence states are present. The low spin-state transition temperature of BSFZ provides that all iron species are in a pure high-spin configuration already above ca. 500 {ring operator} C making this ceramic highly attractive for intermediate temperature applications (500 - 800 {ring operator} C).

Keywords

    EELS, Mössbauer spectroscopy, Perovskite, Spin-state, Valence

ASJC Scopus subject areas

Cite this

Spin-state transition of iron in (Ba0.5 Sr0.5) (Fe0.8 Zn0.2) O3 - δ perovskite. / Feldhoff, Armin; Martynczuk, Julia; Arnold, Mirko et al.
In: Journal of solid state chemistry, Vol. 182, No. 11, 11.2009, p. 2961-2971.

Research output: Contribution to journalArticleResearchpeer review

Feldhoff, A, Martynczuk, J, Arnold, M, Myndyk, M, Bergmann, I, Šepelák, V, Gruner, W, Vogt, U, Hähnel, A & Woltersdorf, J 2009, 'Spin-state transition of iron in (Ba0.5 Sr0.5) (Fe0.8 Zn0.2) O3 - δ perovskite', Journal of solid state chemistry, vol. 182, no. 11, pp. 2961-2971. https://doi.org/10.1016/j.jssc.2009.07.058
Feldhoff, A., Martynczuk, J., Arnold, M., Myndyk, M., Bergmann, I., Šepelák, V., Gruner, W., Vogt, U., Hähnel, A., & Woltersdorf, J. (2009). Spin-state transition of iron in (Ba0.5 Sr0.5) (Fe0.8 Zn0.2) O3 - δ perovskite. Journal of solid state chemistry, 182(11), 2961-2971. https://doi.org/10.1016/j.jssc.2009.07.058
Feldhoff A, Martynczuk J, Arnold M, Myndyk M, Bergmann I, Šepelák V et al. Spin-state transition of iron in (Ba0.5 Sr0.5) (Fe0.8 Zn0.2) O3 - δ perovskite. Journal of solid state chemistry. 2009 Nov;182(11):2961-2971. Epub 2009 Aug 6. doi: 10.1016/j.jssc.2009.07.058
Feldhoff, Armin ; Martynczuk, Julia ; Arnold, Mirko et al. / Spin-state transition of iron in (Ba0.5 Sr0.5) (Fe0.8 Zn0.2) O3 - δ perovskite. In: Journal of solid state chemistry. 2009 ; Vol. 182, No. 11. pp. 2961-2971.
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title = "Spin-state transition of iron in (Ba0.5 Sr0.5) (Fe0.8 Zn0.2) O3 - δ perovskite",
abstract = "The redox behavior of iron during heating of a high-performance perovskite for ceramic oxygen separation membranes was studied by combined electron energy-loss (EELS, esp. ELNES) and M{\"o}ssbauer spectroscopical in situ methods. At room temperature, the iron in (Ba0.5 Sr0.5) (Fe0.8 Zn0.2) O3 - δ (BSFZ) is in a mixed valence state of 75% Fe4 + in the high-spin state and 25% Fe3 + predominantly in the low-spin state. When heated to 900 {ring operator} C, a slight reduction of iron is observed that increases the quantity of Fe3 + species. However, the dominant occurrence is a gradual transition in the spin-state of trivalent iron from a mixed low-spin/high-spin to a pure high-spin configuration. In addition, a remarkable amount of hybridization is found in the Fe-O bonds that are highly polar rather than purely ionic. The coupled valence/spin-state transition correlates with anomalies in thermogravimetry and thermal expansion behavior observed by X-ray diffraction and dilatometry, respectively. Since the effective cationic radii depend not only on the valence but also on the spin-state, both have to be considered when estimating under which conditions a cubic perovskite will tolerate specific cations. It is concluded that an excellent phase stability of perovskite-based membrane materials demands a tailoring, which enables pure high-spin states under operational conditions, even if mixed valence states are present. The low spin-state transition temperature of BSFZ provides that all iron species are in a pure high-spin configuration already above ca. 500 {ring operator} C making this ceramic highly attractive for intermediate temperature applications (500 - 800 {ring operator} C).",
keywords = "EELS, M{\"o}ssbauer spectroscopy, Perovskite, Spin-state, Valence",
author = "Armin Feldhoff and Julia Martynczuk and Mirko Arnold and Maxym Myndyk and Ingo Bergmann and Vladimir {\v S}epel{\'a}k and Wolfgang Gruner and Ulrich Vogt and Angelika H{\"a}hnel and J{\"o}rg Woltersdorf",
note = "Funding Information: We would like to thank Prof. Harald Behrens for putting his high-pressure apparatus at our disposal and Dr. Falk Heinroth for assistance in TGA measurements. Our discussions with Profs. J{\"u}rgen Caro and Haihui Wang were fruitful and are appreciated. This work was financially supported by the Deutsche Forschungsgemeinschaft (DFG) under Grant FE 928/1-2. V.Ŝ. thanks the DFG for supporting his work in the framework of the Priority Program “Crystalline Nonequilibrium Phases” (SPP 1415). Partial support by the Alexander von Humboldt Foundation, the APVV (0728-07), and the VEGA (2/0065/08) is gratefully acknowledged.",
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TY - JOUR

T1 - Spin-state transition of iron in (Ba0.5 Sr0.5) (Fe0.8 Zn0.2) O3 - δ perovskite

AU - Feldhoff, Armin

AU - Martynczuk, Julia

AU - Arnold, Mirko

AU - Myndyk, Maxym

AU - Bergmann, Ingo

AU - Šepelák, Vladimir

AU - Gruner, Wolfgang

AU - Vogt, Ulrich

AU - Hähnel, Angelika

AU - Woltersdorf, Jörg

N1 - Funding Information: We would like to thank Prof. Harald Behrens for putting his high-pressure apparatus at our disposal and Dr. Falk Heinroth for assistance in TGA measurements. Our discussions with Profs. Jürgen Caro and Haihui Wang were fruitful and are appreciated. This work was financially supported by the Deutsche Forschungsgemeinschaft (DFG) under Grant FE 928/1-2. V.Ŝ. thanks the DFG for supporting his work in the framework of the Priority Program “Crystalline Nonequilibrium Phases” (SPP 1415). Partial support by the Alexander von Humboldt Foundation, the APVV (0728-07), and the VEGA (2/0065/08) is gratefully acknowledged.

PY - 2009/11

Y1 - 2009/11

N2 - The redox behavior of iron during heating of a high-performance perovskite for ceramic oxygen separation membranes was studied by combined electron energy-loss (EELS, esp. ELNES) and Mössbauer spectroscopical in situ methods. At room temperature, the iron in (Ba0.5 Sr0.5) (Fe0.8 Zn0.2) O3 - δ (BSFZ) is in a mixed valence state of 75% Fe4 + in the high-spin state and 25% Fe3 + predominantly in the low-spin state. When heated to 900 {ring operator} C, a slight reduction of iron is observed that increases the quantity of Fe3 + species. However, the dominant occurrence is a gradual transition in the spin-state of trivalent iron from a mixed low-spin/high-spin to a pure high-spin configuration. In addition, a remarkable amount of hybridization is found in the Fe-O bonds that are highly polar rather than purely ionic. The coupled valence/spin-state transition correlates with anomalies in thermogravimetry and thermal expansion behavior observed by X-ray diffraction and dilatometry, respectively. Since the effective cationic radii depend not only on the valence but also on the spin-state, both have to be considered when estimating under which conditions a cubic perovskite will tolerate specific cations. It is concluded that an excellent phase stability of perovskite-based membrane materials demands a tailoring, which enables pure high-spin states under operational conditions, even if mixed valence states are present. The low spin-state transition temperature of BSFZ provides that all iron species are in a pure high-spin configuration already above ca. 500 {ring operator} C making this ceramic highly attractive for intermediate temperature applications (500 - 800 {ring operator} C).

AB - The redox behavior of iron during heating of a high-performance perovskite for ceramic oxygen separation membranes was studied by combined electron energy-loss (EELS, esp. ELNES) and Mössbauer spectroscopical in situ methods. At room temperature, the iron in (Ba0.5 Sr0.5) (Fe0.8 Zn0.2) O3 - δ (BSFZ) is in a mixed valence state of 75% Fe4 + in the high-spin state and 25% Fe3 + predominantly in the low-spin state. When heated to 900 {ring operator} C, a slight reduction of iron is observed that increases the quantity of Fe3 + species. However, the dominant occurrence is a gradual transition in the spin-state of trivalent iron from a mixed low-spin/high-spin to a pure high-spin configuration. In addition, a remarkable amount of hybridization is found in the Fe-O bonds that are highly polar rather than purely ionic. The coupled valence/spin-state transition correlates with anomalies in thermogravimetry and thermal expansion behavior observed by X-ray diffraction and dilatometry, respectively. Since the effective cationic radii depend not only on the valence but also on the spin-state, both have to be considered when estimating under which conditions a cubic perovskite will tolerate specific cations. It is concluded that an excellent phase stability of perovskite-based membrane materials demands a tailoring, which enables pure high-spin states under operational conditions, even if mixed valence states are present. The low spin-state transition temperature of BSFZ provides that all iron species are in a pure high-spin configuration already above ca. 500 {ring operator} C making this ceramic highly attractive for intermediate temperature applications (500 - 800 {ring operator} C).

KW - EELS

KW - Mössbauer spectroscopy

KW - Perovskite

KW - Spin-state

KW - Valence

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DO - 10.1016/j.jssc.2009.07.058

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JO - Journal of solid state chemistry

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