Iron mixed-valence compounds, BaSm(Cu0.5+xFe0.5-x)2O5+δ. II: the Fe2.5+ state and magnetic properties

J. Lindén; J. Nakamura; T. Pietari; T. Taniyama; M. Karppinen; H. Yamauchi

doi:10.1016/S0921-4534(00)00214-8

Iron mixed-valence compounds, BaSm(Cu_0.5+xFe_0.5-x)₂O_5+δ. II: the Fe^2.5+ state and magnetic properties

J. Lindén^*
, J. Nakamura
, T. Pietari
, T. Taniyama
, M. Karppinen
, H. Yamauchi

^*Korresponderande författare för detta arbete

Fysik

Forskningsoutput: Tidskriftsbidrag › Konferensartikel › Vetenskaplig › Peer review

Sammanfattning

Recently, a fluctuating mixed-valence state formally denoted as Fe^2.5+ was observed in BaSmFe₂O_5+δ double-perovskite samples, having δ < 0.5 [J. Linden, P. Karen, A. Kjekshus, J. Miettinen, T. Pietari, M. Karppinen, Phys. Rev. B 60 (1999) 15251.]. Upon cooling such samples to the Verwey-type transition temperature (T_V ≈ 200 K), a mixing-separation transition of the valence state occurs. In order to study in detail the formation of the mixed-valence state BaSm(Cu_0.5+xFe_0.5-x)₂O_5+δ, samples with a certain amount of Fe (0-10% and 40-50%) replaced by Cu have been characterized by ⁵⁷Fe Mossbauer spectroscopy and magnetization measurements. All samples were found to be magnetically ordered at room temperature. The amount of Fe entering the Fe^2.5+ state decreased rapidly as the Cu doping level was increased, as judged by the Mossbauer spectra. Increasing the Cu concentration also led to an increase of T_V.

Originalspråk	Engelska
Sidor (från-till)	126-131
Antal sidor	6
Tidskrift	Physica C: Superconductivity and its Applications
Volym	338
Nummer	1
DOI	https://doi.org/10.1016/S0921-4534(00)00214-8
Status	Publicerad - 1 aug. 2000
MoE-publikationstyp	A4 Artikel i en konferenspublikation
Evenemang	International Discussion Meeting on Chemistry Approaches to High-Tc Superconductive Materials / 5th International Workshop on Chemical Designing and Processing of High-Tc Superconductors (Chem-HTSC-V) - Yokohama, Jpn Varaktighet: 15 okt. 1999 → 16 okt. 1999

Finansiering

One of the authors (J.L.) acknowledges kind support from the Japan Society for the Promotion of Science. The present work has been supported by a Grant-in-Aid for Scientific Research (contract No. 11305002) from The Ministry of Education, Science and Culture of Japan, and also by an International Collaborative Research Project Grant-1999 of the Materials and Structures Laboratory, Tokyo Institute of Technology.

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10.1016/S0921-4534(00)00214-8

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title = "Iron mixed-valence compounds, BaSm(Cu0.5+xFe0.5-x)2O5+δ. II: the Fe2.5+ state and magnetic properties",

abstract = "Recently, a fluctuating mixed-valence state formally denoted as Fe2.5+ was observed in BaSmFe2O5+δ double-perovskite samples, having δ < 0.5 [J. Linden, P. Karen, A. Kjekshus, J. Miettinen, T. Pietari, M. Karppinen, Phys. Rev. B 60 (1999) 15251.]. Upon cooling such samples to the Verwey-type transition temperature (TV ≈ 200 K), a mixing-separation transition of the valence state occurs. In order to study in detail the formation of the mixed-valence state BaSm(Cu0.5+xFe0.5-x)2O5+δ, samples with a certain amount of Fe (0-10\% and 40-50\%) replaced by Cu have been characterized by 57Fe Mossbauer spectroscopy and magnetization measurements. All samples were found to be magnetically ordered at room temperature. The amount of Fe entering the Fe2.5+ state decreased rapidly as the Cu doping level was increased, as judged by the Mossbauer spectra. Increasing the Cu concentration also led to an increase of TV.",

author = "J. Lind{\'e}n and J. Nakamura and T. Pietari and T. Taniyama and M. Karppinen and H. Yamauchi",

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T2 - International Discussion Meeting on Chemistry Approaches to High-Tc Superconductive Materials / 5th International Workshop on Chemical Designing and Processing of High-Tc Superconductors (Chem-HTSC-V)

AU - Lindén, J.

AU - Nakamura, J.

AU - Pietari, T.

AU - Taniyama, T.

AU - Karppinen, M.

AU - Yamauchi, H.

PY - 2000/8/1

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N2 - Recently, a fluctuating mixed-valence state formally denoted as Fe2.5+ was observed in BaSmFe2O5+δ double-perovskite samples, having δ < 0.5 [J. Linden, P. Karen, A. Kjekshus, J. Miettinen, T. Pietari, M. Karppinen, Phys. Rev. B 60 (1999) 15251.]. Upon cooling such samples to the Verwey-type transition temperature (TV ≈ 200 K), a mixing-separation transition of the valence state occurs. In order to study in detail the formation of the mixed-valence state BaSm(Cu0.5+xFe0.5-x)2O5+δ, samples with a certain amount of Fe (0-10% and 40-50%) replaced by Cu have been characterized by 57Fe Mossbauer spectroscopy and magnetization measurements. All samples were found to be magnetically ordered at room temperature. The amount of Fe entering the Fe2.5+ state decreased rapidly as the Cu doping level was increased, as judged by the Mossbauer spectra. Increasing the Cu concentration also led to an increase of TV.

AB - Recently, a fluctuating mixed-valence state formally denoted as Fe2.5+ was observed in BaSmFe2O5+δ double-perovskite samples, having δ < 0.5 [J. Linden, P. Karen, A. Kjekshus, J. Miettinen, T. Pietari, M. Karppinen, Phys. Rev. B 60 (1999) 15251.]. Upon cooling such samples to the Verwey-type transition temperature (TV ≈ 200 K), a mixing-separation transition of the valence state occurs. In order to study in detail the formation of the mixed-valence state BaSm(Cu0.5+xFe0.5-x)2O5+δ, samples with a certain amount of Fe (0-10% and 40-50%) replaced by Cu have been characterized by 57Fe Mossbauer spectroscopy and magnetization measurements. All samples were found to be magnetically ordered at room temperature. The amount of Fe entering the Fe2.5+ state decreased rapidly as the Cu doping level was increased, as judged by the Mossbauer spectra. Increasing the Cu concentration also led to an increase of TV.

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