摘要
Water soluble upconversion （UC） luminescence hexagonal-phase NaGdF4： yb3＋/Tm3＋ nanoparticles have been successfully synthesized by the hydrothermal method. XRD, SEM, UC photoluminescence spectra and electron paramagnetic resonance （EPR） spectrum were used to characterize the nanoparticles. The intensity of UC emission region could be controlled through different sodium source and the fluorine source, 6PJ→8S7/2 emission of Gd3＋ is also observed at 310 nm. A broad spectrum with a dominant resonance at g of about 2 was observed by the EPR spectrum of the NaGdF4：Yb3＋/Tm3＋ nanoparticles. The transparent NaGdF4：yb3＋/Tm3＋ solution presented naked eye-visible violet-blue light under the 980 nm LD excitation. The current work paves the way for their potential application in infrared tomography and magnetic resonance imaging （MRI）.
Water soluble upconversion （UC） luminescence hexagonal-phase NaGdF4： yb3＋/Tm3＋ nanoparticles have been successfully synthesized by the hydrothermal method. XRD, SEM, UC photoluminescence spectra and electron paramagnetic resonance （EPR） spectrum were used to characterize the nanoparticles. The intensity of UC emission region could be controlled through different sodium source and the fluorine source, 6PJ→8S7/2 emission of Gd3＋ is also observed at 310 nm. A broad spectrum with a dominant resonance at g of about 2 was observed by the EPR spectrum of the NaGdF4：Yb3＋/Tm3＋ nanoparticles. The transparent NaGdF4：yb3＋/Tm3＋ solution presented naked eye-visible violet-blue light under the 980 nm LD excitation. The current work paves the way for their potential application in infrared tomography and magnetic resonance imaging （MRI）.
基金
Acknowledgements This work was supported by the National Natural Science Foundation of China （Grant No. 51361009）, Key Program for International S＆T Cooperation Projects of Hainan Province, China （GJXM201103）, Science and Technology Department of Hainan Province, China （Grant No. 090401）, and the Natural Science Foundation of Hainan Province, China （Grant No. 513136）.
