期刊
JOURNAL OF PHYSICAL CHEMISTRY C
卷 113, 期 2, 页码 610-617出版社
AMER CHEMICAL SOC
DOI: 10.1021/jp808688w
关键词
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资金
- Korean Government (MOEHRD, Basic Research Promotion Fund) [KRF-2007-412-J00902]
- MOST
- KOSEF [R15-2006-022-03001-0]
- National Research Foundation of Korea [핵06B2812, 2006-0052001] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
Nanocrystalline Eu3+-doped CeO2, CeO2, Sm3+-doped CeO2, and Li+, Eu3+-codoped CeO2 samples were prepared through a sol-gel process. The structure and the optical properties of the samples were characterized by X-ray diffraction, diffuse reflection spectra, and photoluminescence spectra. No luminescence was observed for nanocrystalline CeO2. The systematic investigation shows that the broad band in the excitation spectrum of CeO2:Eu3+ comes from the charge transfer (CT) transition from O2- to Ce4+, not from the oxygen vacancy, or from the CT of O2- to Eu3+. Upon increasing the fired temperature from 600 to 800 degrees C, the excitation spectrum shifts to lower energy. With increasing concentrations of Eu3+ up to 1% in CeO2, red shifts of the excitation spectra are observed; however, when the concentration of Eu3+ increases to 5% and 10%, blue shifts occur. The emission spectrum shows that the symmetry of the Eu3+ site becomes lower with increasing Eu3+. Based on the dielectric theory of complex crystals, the environmental factor (h(e)) and the dielectric definition of average energy gap around the centers of Eu3+ are calculated. The reasons for the shifts of the excitation spectra are discussed in detail.
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