Paramagnetism and improved upconversion luminescence properties of NaYF4：Yb,Er/NaGdF4 nanocomposites synthesized by a boiling water seed-mediated route

作     者：Chao-Qing YANG Ao-Ju LI Wei GUO Peng-Hua TIAN Xiao-Long YU Zhong-Xin LIU Yang CAO Zhong-Liang SUN 

作者机构：Key Laboratory of Ministry of Education for Advanced Materials in Tropical Island Resources Hainan University Haikou 570228 China 

出 版 物：《Frontiers of Materials Science》 (材料学前沿（英文版）)

年 卷 期：2016年第10卷第1期

页      面：38-44页

核心收录：

学科分类：08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0702[理学-物理学] 

基　　金：Acknowledgements Authors would like to acknowledge the National Natural Science Foundation of China (NSFC  Grant No. 51361009)  the International Joint Project of Hainan Province (Grant No. KJHZ2014-19)  the Postgraduate Innovative Project of Hainan Province in 2015 (Grant No. Hys2015-24) and the Postgraduate Practice & Innovation Projects of Hainan University in 2015 for financial support. The Instrumental Analysis Center of Hainan University is also acknowledged here 

主　　题：boiling water upconversion nanoparticle fluorescence imaging paramagnetism 

摘      要：In a route boiling water served as reaction medium, a stoichiometric amount of rare-earth compound and fluoride are put into this system to form a-NaYF4：Yb, Er nuclei. Then prepared sample is heated at elevated temperature to improve the fluorescence intensity, and next a NaGdF4 shell grows on the surface of NaYF4 nuclei. NaYF4：Yb,ErlNaGdF4 core-shell structured upconversion nanoparticles （CSUCNPs） have been successfully synthesized by above route. The use of boiling water decreases the cubic-to-hexagonal phase transition temperature of NaYF4：Yb,Er to 350℃ and increases its upconversion （UC） luminescence intensity. A heterogeneous NaGdF4 epitaxially growing on the surface of Ln^3＋-doped NaYF4 not only improves UC luminescence, but also creates a paramagnetic shell, which can be used as contrast agents in magnetic resonance imaging （MRI）o The solution of CSUCNPs shows bright green UC fluorescence under the excitation at 980 nm in a power density only about 50 ***-2. A broad spectrum with a dominant resonance at g of about 2 is observed by the electron paramagnetic resonance （EPR） spectrum of CSUCNPs. Above properties suggest that the obtained CSUCNPs could be potential candidates for dual-mode optical/magnetic bioapplications.