Solvothermal synthesis and tailored upconversion emission of monodisperse ultrasmall face-centered cubic Sr₂YF₇ nanocrystals

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• 作者：Mo Ma^a ; ^b ; Chang-fu Xu^a ; ^b ; ^{xcf@xtu.edu.cn} ; Li-wen Yang^a ; ^b ; Qi-bin Yang^a ; ^b ; Jian-guo Lin^a ; ^b
• 关键词：Sr2YF7 nanocrystal ; Upconversion ; Monodisperse ; Ultrasmall
• 刊名：Journal of Alloys and Compounds
• 出版年：2012
• 期刊代码：45_09258388
• 类别：ms
• 出版时间：5 June, 2012
• 卷：525
• 期：Complete
• 页码：97-102
• 文件大小：1895 K

摘要

Monodisperse Sr₂YF₇ nanocrystals with the size of sub-10 nm were synthesized via a solvothermal method by using oleate as a capping ligand. X-ray diffraction and transmission electron microscopy assays reveal that the as-synthesized Sr₂YF₇ nanocrystals are face-centered cubic structure with the cell parameter a = 5.704 脜. Intense upconversion luminescence can be observed in Er³⁺/Yb³⁺ and Tm³⁺/Yb³⁺ codoped Sr₂YF₇ nanocrystals under the excitation of a 980 nm laser and near-white-color emission can be obtained in Er³⁺/Tm³⁺/Yb³⁺ tri-doped Sr₂YF₇ nanocrystals. Energy transfer (ET) from Yb³⁺ to Er³⁺ and Tm³⁺ is mainly responsible to pump Er³⁺ and Tm³⁺ from the ground state to higher states. In Er³⁺/Tm³⁺/Yb³⁺ tri-doped Sr₂YF₇ nanocrystals, ET from Tm³⁺ to Er³⁺ leads average three-photon process, which renders the 523 nm emission.