Tb3+- and Eu3+-Doped Lanthanum Oxysulfide Nanocrystals. Gelatin-Templated Synthesis and Luminescence Properties
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- 作者：Zhigang Liu ; Xudong Sun ; Shukun Xu ; Jingbao Lian ; Xiaodong Li ; Zhimeng Xiu ; Qiang Li ; Di Huo ; Ji-Guang Li
- 刊名：Journal of Physical Chemistry C
- 出版年：2008
- 出版时间：February 21, 2008
- 年：2008
- 卷：112
- 期：7
- 页码：2353 - 2358
- 全文大小：251K
- 年卷期：v.112,no.7(February 21, 2008)
- ISSN：1932-7455
文摘
Tb3+- and Eu3+-doped lanthanum oxysulfide nanocrystals (NCs) with homogeneous grain size have beenprepared by a gel-network coprecipitation method using gelatin as the template and ammonium sulfate as thesulfurizing agent and a following reduction process at relatively low temperatures (750 
C) in a H2 atmosphere.The products were characterized using thermogravimetry-differential thermal analysis (TG-DTA), X-raydiffractometry (XRD), and transmission electron microscopy (TEM). The gelatin template can act as a"nanoreactor", which is beneficial to the dispersion and size control of the coprecipitation product. The highdecomposition temperature (about 482 C) of the gelatin network is advantageous to prevent aggregation ofthe newly formed (LaO)2SO4 NCs during calcination of the coprecipitation product. Single hexagonal phaseLa2O2S NCs were obtained by reduction of the (LaO)2SO4 powder, and the NCs are equiaxial in shape withparticle sizes ranging from 40 to 50 nm. The photoluminescence spectra and time-resolved spectra of theLa2O2S:Tb(Eu) in phosphate buffer were investigated. The results show that the La2O2S:Tb NCs have a strongluminescence at 544 nm, whose intensity decreases along with decreasing particle size. Concentration quenchingoccurs when the Tb concentration reaches 8 mol %. The fluorescence color of the La2O2S:Eu NCs dependson the concentration of Eu3+ ions. The red emission (at 625 nm) from 5D0 transition has a much longer decaytime than the green emission from 5D1 transition of the La2O2S:Eu NCs. The Tb3+- and the Eu3+-dopedLa2O2S NCs have respective fluorescence lifetimes of 1.10 and 0.41 ms in phosphate buffer, allowing theirpotential applications in biological labeling.
C) in a H2 atmosphere.The products were characterized using thermogravimetry-differential thermal analysis (TG-DTA), X-raydiffractometry (XRD), and transmission electron microscopy (TEM). The gelatin template can act as a"nanoreactor", which is beneficial to the dispersion and size control of the coprecipitation product. The highdecomposition temperature (about 482 C) of the gelatin network is advantageous to prevent aggregation ofthe newly formed (LaO)2SO4 NCs during calcination of the coprecipitation product. Single hexagonal phaseLa2O2S NCs were obtained by reduction of the (LaO)2SO4 powder, and the NCs are equiaxial in shape withparticle sizes ranging from 40 to 50 nm. The photoluminescence spectra and time-resolved spectra of theLa2O2S:Tb(Eu) in phosphate buffer were investigated. The results show that the La2O2S:Tb NCs have a strongluminescence at 544 nm, whose intensity decreases along with decreasing particle size. Concentration quenchingoccurs when the Tb concentration reaches 8 mol %. The fluorescence color of the La2O2S:Eu NCs dependson the concentration of Eu3+ ions. The red emission (at 625 nm) from 5D0 transition has a much longer decaytime than the green emission from 5D1 transition of the La2O2S:Eu NCs. The Tb3+- and the Eu3+-dopedLa2O2S NCs have respective fluorescence lifetimes of 1.10 and 0.41 ms in phosphate buffer, allowing theirpotential applications in biological labeling.