Spin-entropy driven charge-transfer phase transition in iron mixed-valence system

N. Kojima; M. Itoi; Y. Ono; M. Okubo; M. Enomoto

Spin-entropy driven charge-transfer phase transition in iron mixed-valence system

N. Kojima^*, M. Itoi, Y. Ono, M. Okubo, M. Enomoto

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

5 Citations (Scopus)

Abstract

We have synthesized iron mixed-valence complexes, (n-C_nH_2n+1)₄N[Fe^IIFe ^IIIX₃] (X = mto (C₂O3S), dto (C₂O₂S₂), tto (C₂OS₃)) and have investigated their physical properties by means of ⁵⁷Fe Mössbauer spectroscopy, magnetic susceptibility and electrical resistivity measurements. From the analysis of ⁵⁷Fe Mössbauer spectra, magnetic susceptibility and electrical resistivity, we have discovered a new type of first order phase transition around 120 K for (n-C_nH_2n+1)₄N[Fe^IIFe ^III(dto)₃](n = 3, 4), where the charge-transfer transition between Fe^II and Fe^III occurs reversibly. In the higher temperature phase, the Fe^III (S = 1/2) and Fe^II (S = 2) sites are co-ordinated by six S atoms and six O atoms, respectively. In the lower temperature phase, on the other hand, the Fe^III (S = 5/2) and Fe^II (S = 0) sites are co-ordinated by six O atoms and six S atoms, respectively. Moreover, we have found a ferromagnetic phase transition in this system. The ferromagnetic order is induced by the charge-transfer interaction between the Fe^III and Fe^II sites. We propose various multifunctional properties for (nC_nH_2n+1)₄N[Fe^IIFe ^III(mto)₃] and (n-C_nH_2n+1)₄N[Fe^IIFe ^III(tto)₃].

Original language	English
Pages (from-to)	181-189
Number of pages	9
Journal	Materials Science- Poland
Volume	21
Issue number	2
Publication status	Published - 2003
Externally published	Yes

Keywords

Charge-transfer
Ferromagnetism
Mixed valence
Phase transition
Spin crossover

ASJC Scopus subject areas

Materials Science(all)
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering

Cite this

@article{b819fa45f90d41649ec8d83c243ea0c0,

title = "Spin-entropy driven charge-transfer phase transition in iron mixed-valence system",

abstract = "We have synthesized iron mixed-valence complexes, (n-CnH2n+1)4N[FeIIFe IIIX3] (X = mto (C2O3S), dto (C2O2S2), tto (C2OS3)) and have investigated their physical properties by means of 57Fe M{\"o}ssbauer spectroscopy, magnetic susceptibility and electrical resistivity measurements. From the analysis of 57Fe M{\"o}ssbauer spectra, magnetic susceptibility and electrical resistivity, we have discovered a new type of first order phase transition around 120 K for (n-CnH2n+1)4N[FeIIFe III(dto)3](n = 3, 4), where the charge-transfer transition between FeII and FeIII occurs reversibly. In the higher temperature phase, the FeIII (S = 1/2) and FeII (S = 2) sites are co-ordinated by six S atoms and six O atoms, respectively. In the lower temperature phase, on the other hand, the FeIII (S = 5/2) and FeII (S = 0) sites are co-ordinated by six O atoms and six S atoms, respectively. Moreover, we have found a ferromagnetic phase transition in this system. The ferromagnetic order is induced by the charge-transfer interaction between the FeIII and FeII sites. We propose various multifunctional properties for (nCnH2n+1)4N[FeIIFe III(mto)3] and (n-CnH2n+1)4N[FeIIFe III(tto)3].",

keywords = "Charge-transfer, Ferromagnetism, Mixed valence, Phase transition, Spin crossover",

author = "N. Kojima and M. Itoi and Y. Ono and M. Okubo and M. Enomoto",

year = "2003",

language = "English",

volume = "21",

pages = "181--189",

journal = "Materials Science- Poland",

issn = "0137-1339",

publisher = "Walter de Gruyter GmbH",

number = "2",

}

TY - JOUR

T1 - Spin-entropy driven charge-transfer phase transition in iron mixed-valence system

AU - Kojima, N.

AU - Itoi, M.

AU - Ono, Y.

AU - Okubo, M.

AU - Enomoto, M.

PY - 2003

Y1 - 2003

N2 - We have synthesized iron mixed-valence complexes, (n-CnH2n+1)4N[FeIIFe IIIX3] (X = mto (C2O3S), dto (C2O2S2), tto (C2OS3)) and have investigated their physical properties by means of 57Fe Mössbauer spectroscopy, magnetic susceptibility and electrical resistivity measurements. From the analysis of 57Fe Mössbauer spectra, magnetic susceptibility and electrical resistivity, we have discovered a new type of first order phase transition around 120 K for (n-CnH2n+1)4N[FeIIFe III(dto)3](n = 3, 4), where the charge-transfer transition between FeII and FeIII occurs reversibly. In the higher temperature phase, the FeIII (S = 1/2) and FeII (S = 2) sites are co-ordinated by six S atoms and six O atoms, respectively. In the lower temperature phase, on the other hand, the FeIII (S = 5/2) and FeII (S = 0) sites are co-ordinated by six O atoms and six S atoms, respectively. Moreover, we have found a ferromagnetic phase transition in this system. The ferromagnetic order is induced by the charge-transfer interaction between the FeIII and FeII sites. We propose various multifunctional properties for (nCnH2n+1)4N[FeIIFe III(mto)3] and (n-CnH2n+1)4N[FeIIFe III(tto)3].

AB - We have synthesized iron mixed-valence complexes, (n-CnH2n+1)4N[FeIIFe IIIX3] (X = mto (C2O3S), dto (C2O2S2), tto (C2OS3)) and have investigated their physical properties by means of 57Fe Mössbauer spectroscopy, magnetic susceptibility and electrical resistivity measurements. From the analysis of 57Fe Mössbauer spectra, magnetic susceptibility and electrical resistivity, we have discovered a new type of first order phase transition around 120 K for (n-CnH2n+1)4N[FeIIFe III(dto)3](n = 3, 4), where the charge-transfer transition between FeII and FeIII occurs reversibly. In the higher temperature phase, the FeIII (S = 1/2) and FeII (S = 2) sites are co-ordinated by six S atoms and six O atoms, respectively. In the lower temperature phase, on the other hand, the FeIII (S = 5/2) and FeII (S = 0) sites are co-ordinated by six O atoms and six S atoms, respectively. Moreover, we have found a ferromagnetic phase transition in this system. The ferromagnetic order is induced by the charge-transfer interaction between the FeIII and FeII sites. We propose various multifunctional properties for (nCnH2n+1)4N[FeIIFe III(mto)3] and (n-CnH2n+1)4N[FeIIFe III(tto)3].

KW - Charge-transfer

KW - Ferromagnetism

KW - Mixed valence

KW - Phase transition

KW - Spin crossover

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UR - http://www.scopus.com/inward/citedby.url?scp=18244362368&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:18244362368

SN - 0137-1339

VL - 21

SP - 181

EP - 189

JO - Materials Science- Poland

JF - Materials Science- Poland

IS - 2

ER -

Spin-entropy driven charge-transfer phase transition in iron mixed-valence system

Abstract

Keywords

ASJC Scopus subject areas

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