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Yasuhara S, Hamasaki Y, Katayama T, Ao T, Inaguma Y, Hojo H, Karppinen M, Philip A, Yasui S, Itoh M. Modulating the Structure and Magnetic Properties of ε-Fe 2O 3 Nanoparticles via Electrochemical Li + Insertion. Inorg Chem 2020; 59:4357-4365. [PMID: 32186859 DOI: 10.1021/acs.inorgchem.9b03302] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
ε-Fe2O3, a metastable phase of iron oxide, is widely known as a room-temperature multiferroic material or as a superhard magnet. Element substitution into ε-Fe2O3 has been reported in the literature; however, the substituted ions have a strong site preference depending on their ionic radii and valence. In this study, in order to characterize the crystal structure and magnetic properties of ε-Fe2O3 in the Fe2+/Fe3+ coexisting states, Li+ was electrochemically inserted into ε-Fe2O3 to reduce Fe3+. The discharge and charge of Li+ into/from ε-Fe2O3 revealed that Li+ insertion was successful. X-ray magnetic circular dichroism results indicated that the reduced Fe did not exhibit site preference. Increasing the Li+ content in ε-Fe2O3 resulted in decreased saturation magnetization and irregular variation of the coercive field. We present a comprehensive discussion of how magnetic properties are modified with increasing Li+ content using transmission electron microscopy images and considering the Li+ diffusion coefficient. The results suggest that inserting Li+ into crystalline ε-Fe2O3 is a useful tool for characterizing crystal structure, lithiation limit, and magnetic properties in the coexistence of Fe2+/Fe3+.
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Affiliation(s)
- Sou Yasuhara
- Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
| | - Yosuke Hamasaki
- Department of Applied Physics, National Defense Academy, 1-10-20 Hashirimizu, Yokosuka 239-8686, Japan
| | - Tsukasa Katayama
- Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takahiro Ao
- Department of Chemistry, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan
| | - Yoshiyuki Inaguma
- Department of Chemistry, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo 171-8588, Japan
| | - Hajime Hojo
- Department of Advanced Materials Science and Engineering, Kyushu University, 6-1 Kasuga Koen, Kasuga, Fukuoka 816-8580, Japan
| | - Maarit Karppinen
- Department of Chemistry and Materials Science, Aalto University, FI-00076 Espoo, Finland
| | - Anish Philip
- Department of Chemistry and Materials Science, Aalto University, FI-00076 Espoo, Finland
| | - Shintaro Yasui
- Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
| | - Mitsuru Itoh
- Laboratory for Materials and Structures, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
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Abstract
Nanoparticles of alpha-Fe2O3 (hematite) typically have the sublattice magnetization directions in the hexagonal (001) plane below the Ne el temperature. By use of Mo ssbauer spectroscopy we have found that for agglomerated particles the sublattice magnetization may be rotated of the order of 15 degrees out of plane, depending on the particle size. The spin rotation can be explained by exchange interaction between neighboring particles with nonparallel (001) planes. The results imply that interparticle interactions can lead to spin directions deviating from the easy axis defined by the magnetic anisotropy.
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Affiliation(s)
- Cathrine Frandsen
- Department of Physics, Building 307, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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Gao X, Shen J, Hsia Y, Chen Y. Reduction of supported iron oxide studied by temperature-programmed reduction combined with mössbauer spectroscopy and X-ray diffraction. ACTA ACUST UNITED AC 1993. [DOI: 10.1039/ft9938901079] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Williamson DL, Venturini EL, Graham RA, Morosin B. Morin transition of shock-modified hematite. Phys Rev B Condens Matter 1986; 34:1899-1907. [PMID: 9939847 DOI: 10.1103/physrevb.34.1899] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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