Highly Uniform and Monodisperse -NaYF4:Ln3+ (Ln = Eu, Tb, Yb/Er, and Yb/Tm) Hexagonal Micropris
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- 作者：Chunxia Li ; Zewei Quan ; Jun Yang ; Piaoping Yang ; Jun Lin
- 刊名：Inorganic Chemistry
- 出版年：2007
- 出版时间：August 6, 2007
- 年：2007
- 卷：46
- 期：16
- 页码：6329 - 6337
- 全文大小：759K
- 年卷期：v.46,no.16(August 6, 2007)
- ISSN：1520-510X
文摘
-NaYF4:Ln3+ (Ln = Eu, Tb, Yb/Er, and Yb/Tm) hexagonal microprisms with remarkably uniform morphology andsize have been synthesized via a facile hydrothermal route. X-ray diffraction (XRD), scanning electron microscopy(SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), andphotoluminescence (PL) spectra as well as kinetic decays were used to characterize the samples. It is found thatsodium citrate as a shape modifier introduced into the reaction system plays a critical role in the shape evolutionof the final products. Furthermore, the shape and size of the products can be further manipulated by adjusting themolar ratio of citrate/RE3+ (RE represents the total amount of Y3+ and the doped rare earth elements such as Eu3+,Tb3+, Yb3+/Er3+, or Yb3+/Tm3+). Under the excitation of 397 nm ultraviolet light, NaYF4:xEu3+ (x = 1.5, 5%) showsthe emission lines of Eu3+ corresponding to 5D0-3 
7FJ (J = 0-4) transitions from 400 to 700 nm (whole visiblespectral region) with different intensity, resulting in yellow and red down-conversion (DC) light emissions, respectively.When doped with 5% Tb3+ ions, the strong DC fluorescence corresponding to 5D4 7FJ (J = 6, 5, 4, 3) transitionswith 5D4 7F5 (green emission at 544 nm) being the most prominent group that has been observed. In addition,under 980 nm laser excitation, the Yb3+/Er3+- and Yb3+/Tm3+-codoped -NaYF4 samples exhibit bright green andwhitish blue up-conversion (UC) luminescence, respectively. The luminescence mechanisms for the doped lanthanideions were thoroughly analyzed.