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    Please use this identifier to cite or link to this item: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/96247

    Title: Towards understanding the electronic structure of Fe-doped CeO2 nanoparticles with X-ray spectroscopy
    Authors: Wang, Wei-Cheng;Chen, Shih-Yun;Glans, Per-Anders;Guo, Jinghua;Chen, Ren-Jie;Fong, Kang-Wei;Chen, Chi-Liang;Gloter, Alexandre;Chang, Ching-Lin;Chan, Ting-Shan;Chen, Jin-Ming;Lee, Jyh-Fu;Dong, Chung-Li
    Contributors: 淡江大學物理學系
    Date: 2013
    Issue Date: 2014-03-06 16:47:20 (UTC+8)
    Publisher: Cambridge: Physical Chemistry Chemical Physics
    Abstract: This study reports on the electronic structure of Fe-doped CeO2 nanoparticles (NPs), determined by coupled X-ray absorption spectroscopy and X-ray emission spectroscopy. A comparison of the local electronic structure around the Ce site with that around the Fe site indicates that the Fe substitutes for the Ce. The oxygen K-edge spectra that originated from the hybridization between cerium 4f and oxygen 2p states are sensitive to the oxidation state and depend strongly on the concentration of Fe doping. The Ce M4,5-edges and the Fe L2,3-edges reveal the variations of the charge states of Ce and Fe upon doping, respectively. The band gap is further obtained from the combined absorption–emission spectrum and decreased upon Fe doping, implying Fe doping introduces vacancies. The oxygen vacancies are induced by Fe doping and the spectrum reveals the charge transfer between Fe and Ce. Fe3+ doping has two major effects on the formation of ferromagnetism in CeO2 nanoparticles. The first, at an Fe content of below 5%, is that the formation of Fe3+–Vo–Ce3+ introduces oxygen deficiencies favoring ferromagnetism. The other, at an Fe content of over 5%, is the formation of Fe3+–Vo–Fe3+, which favors antiferromagnetism, reducing the Ms. The defect structures Fe3+–Vo–Ce3+ and Fe3+–Vo–Fe3+ are crucial to the magnetism in these NPs and the change in Ms can be described as the effect of competitive interactions of magnetic polarons and paired ions.
    Relation: Physical Chemistry Chemical Physics 15(35), pp.14701-14707
    DOI: 10.1039/C3CP52054D
    Appears in Collections:[物理學系暨研究所] 期刊論文

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