Photoluminescence Properties of CeO2:Eu3+ Nanoparticles Synthesized by a Sol-Gel Method

详细信息    查看全文

• 作者：Ling Li ; Hyun Kyoung Yang ; Byung Kee Moon ; Zuoling Fu ; Chongfeng Guo ; Jung Hyun Jeong ; Soung Soo Yi ; Kiwan Jang ; Ho Sueb Lee
• 刊名：Journal of Physical Chemistry C
• 出版年：2009
• 出版时间：January 15, 2009
• 年：2009
• 卷：113
• 期：2
• 页码：610-617
• 全文大小：477K
• 年卷期：v.113,no.2(January 15, 2009)
• ISSN：1932-7455

文摘

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 °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.