Room temperature ferromagnetic behavior in the hollandite-type titanium oxide
Room temperature ferromagnetic behavior in the hollandite-type titanium oxide
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DOI：
10.1063/1.3369500
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发表时间：
2010-04
影响因子：
3.2
通讯作者：
K. Noami;Y. Muraoka;T. Wakita;M. Hirai;Y. Kato;T. Muro;Y. Tamenori;T. Yokoya
中科院分区：
文献类型：
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作者：
K. Noami;Y. Muraoka;T. Wakita;M. Hirai;Y. Kato;T. Muro;Y. Tamenori;T. Yokoya
本文制备了一种奥朗德型K（x）Ti（8）O（16）多晶样品，并对其进行了磁化强度、电阻率和X射线光电子能谱（XPS）研究。在磁滞测量中观察到室温铁磁行为。在电阻率测量中，样品显示出温度依赖性。对Ti 2 p（3/2）芯能级XPS谱的分析表明，钛离子具有Ti（4+）和Ti（3+）的混合价态。此外，价带谱表明，在Hollandite型TiO（2）晶格中，3d电子倾向于局域在Ti（3+）离子上.此外，价带谱的分析表明，所制备的样品是一个宽带隙的氧化物与3.6 eV的带隙。这些结果表明，本发明的奥朗石型K（x）Ti（8）O（16）样品可以归类为居里温度高于室温的TiO（2）基宽带隙半导体。在强还原性气氛下制备的样品，室温铁磁性（RTFM）降低，同时电阻率降低。结果表明，K（x）Ti（8）O（16）样品的RTFM是由定域的3d电子引起的.
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.