ID | 48849 |
FullText URL | |
Author |
Noami, K.
Muraoka, Y.
Kaken ID
researchmap
Wakita, T.
Hirai, M.
Kato, Y.
Muro, T.
Tamenori, Y.
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Abstract | A hollandite-type K(x)Ti(8)O(16) polycrystalline sample has been prepared and studied by magnetization, resistivity and x-ray photoelectron spectroscopy (XPS). Room temperature ferromagnetic behavior is observed in the magnetic hysteresis measurement. The sample shows a semiconductive temperature dependence in the resistivity measurement. Analysis of the Ti 2p(3/2) core-level XPS spectrum indicates that the titanium ions have a mixed valence of Ti(4+) and Ti(3+). In addition, the valence band spectrum reveals that the 3d electrons tend to localize on Ti(3+) ions in the hollandite-type TiO(2) lattice. Also, analysis of the valence band spectrum shows that the prepared sample is a wide-gap oxide with a band gap of 3.6 eV. These results indicate that the present hollandite-type K(x)Ti(8)O(16) sample can be classified as a TiO(2)-based wide-gap semiconductor with Curie temperature above room temperature. Room temperature ferromagnetism (RTFM) decreases in the sample prepared under a strong reducing gas atmosphere, accompanied with the decrease in the resistivity. The results imply that the localized 3d electrons are responsible for the RTFM of the K(x)Ti(8)O(16) sample.
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Published Date | 2010-04-01
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Publication Title |
Journal of Applied Physics
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Volume | volume107
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Issue | issue7
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Publisher | American Institute of Physics.
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Start Page | 073910-1
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End Page | 073910-6
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ISSN | 0021-8979
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Content Type |
Journal Article
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Project |
Research Center of New Functional Materials for Energy Production, Storage, and Transport
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Official Url | http://dx.doi.org/10.1063/1.3369500
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language |
English
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Copyright Holders | © 2010 American Institute of Physics.
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File Version | publisher
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Refereed |
True
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DOI | |
Web of Science KeyUT |