Synthesis, Characterization And Luminescence Properties Of Upconversion Luminescent Materials

The experiment and theory study of upconversion luminescence(UCL)material have become one of the hotspots in the research fields of advanced materials now, because of the extensive application prospect in the area of three dimensional display, laser anti-counterfeiting brand and biology molecule fluorescence label.This paper mainly research on the synthesis and luminescence property of Y₂SiO₅:Er, Y₂SiO₅:Er,Yb bulk materials and Y₂O₃:Er,Yb,Y₂O₂S:Er,Yb nano-materials.The main contents and results are as following:(1)The upconversion phosphor samples of Y₂SiO₅:Er were prepared by solid state method,and the lithium carbonate was used as reactive flux.The phase and luminescent properties of samples were characterized by X-ray diffraction(XRD)analysis and spectroscopic analysis.The results show that the samples were X1 and type Y₂SiO₅ after calcined at 1300 and 1400℃,respectively.Furthermore,we found that in the same doped concentration,the upconversion luminescence intensity of X2 type Y₂SiO₅ was larger than that of X1 type.In addition,the influence of different Er³⁺ions doped concentration on luminescence properties was studied detailedly.The results showed the optimum doped concentration of Er³⁺ions was 1.0mol%.The possible upconversion mechanisms were discussed.(2)On the base of successful prepare X2 type Y₂SiO₅:Er,the X2 type Y₂SiO₅:Er,Yb samples also were synthesized.The influence of Yb³⁺ions doped concentration on luminescence properties was studied detailedly.The results showed that with the increase of Yb³⁺ions concentration,the intensity of red and green upconversion emission firstly increased and then decreased,and the ratio of red and green upconversion emission intensity drastically increased.As the Er³⁺and Yb³⁺were 1.0mol%and 12.0mol%,respectively,under pumping of several mW powers,the pure red upconversion luminescence was found.The possible upconversion mechanisms were discussed detailedly.(3)The nano-scale upconversion phosphor samples of Y₂O₃:Er,Yb were synthesized by direct precipitation method,and the ammonium hydrogen carbonate was used as the precipitator.In the nitrogen atmosphere,Y₂O₂S:Er,Yb nano-materials were synthesized by sulfurization of Y₂O₃:Er,Yb.The phase,particle size and morphology were characterized by XRD and transmission electron microscope(TEM).The influence of Yb³⁺ions concentration and calcined temperature on upconversion luminescence properties of Y₂O₃:Er,Yb was studied,and energy transfer mechanism of rare earth ions was discussed.Furthermore,the upconversion spectra of Y₂O₃:Er,Yb and Y₂O₂S:Er,Yb were compared,and the influence of host materials on upconversion luminescence properties was discussed detailedly.