Local Structure of Nanocrystalline Lu2O3:Eu Studied by X-ray Absorption Spectroscopy

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• 作者：Zeming Qi ; Miao Liu ; Yonghu Chen ; Guobin Zhang ; Mei Xu ; Chaoshu Shi ; Weiping Zhang ; Min Yin ; Yaning Xie
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：February 8, 2007
• 年：2007
• 卷：111
• 期：5
• 页码：1945 - 1950
• 全文大小：202K
• 年卷期：v.111,no.5(February 8, 2007)
• ISSN：1932-7455

文摘

Eu-doped nanocrystalline Lu₂O₃ with different particle sizes was prepared by combustion synthesis. Thelocal structures around the rare-earth Lu and Eu ions were studied by using both Lu and Eu L₃ edge X-rayabsorption spectroscopy. According to the extended X-ray absorption fine structure (EXAFS) analysis, detailedlocal structure information such as coordination numbers, bonding length, and disorder has been obtained.The results showed that the samples with a particle size larger than 5 nm keep the cubic structure and thedisorder increases with decreasing size. However, when the particle size is smaller than 5 nm, the existenceof considerable amorphous components accounts for the rough interface and the obvious change of the localstructure around the rare-earth ions. A new type of coordination environment around Eu was formed, and themost probable symmetry of the Eu³⁺ site was determined by combining the real-space self-consistent fieldfull multiple scattering X-ray absorption near edge structure (XANES) calculation and the EXAFS result.The local structure information obtained from EXAFS and XANES was used to explain the size-dependentluminescent properties of the nanocrystalline Lu₂O₃:Eu. The decreasing intensity ratio between the hostabsorption band and the Eu³⁺-O^2- charge-transfer state (CTS) band with decreasing particle size can beattributed to a larger disorder and more defects in the small sized samples, while the red shift of the CTSband in the smaller size particles can be ascribed to the longer Eu-O bond length and the higher coordinationnumber.