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ID 48849
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Author
Noami, K.
Wakita, T.
Hirai, M.
Kato, Y.
Muro, T.
Tamenori, Y.
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.
Published Date
2010-04-01
Publication Title
Journal of Applied Physics
Volume
volume107
Issue
issue7
Publisher
American Institute of Physics.
Start Page
073910-1
End Page
073910-6
ISSN
0021-8979
Content Type
Journal Article
Project
Research Center of New Functional Materials for Energy Production, Storage, and Transport
Official Url
http://dx.doi.org/10.1063/1.3369500
language
英語
Copyright Holders
© 2010 American Institute of Physics.
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publisher
Refereed
True
DOI
Web of Sience KeyUT