Research On Preparation And Upconversion Properties Of LiTaO₃:Ho³⁺/Yb³⁺/Tm³⁺ Poly Crystals Luminescence Materials

Up-conversion fluorescent materials have a wide range of applications,and have been applied in many fields such as medical,lighting,energy,scientific research,etc.,and have gradually become a research star in the 21st century.The up-conversion properties of rare earth doped LiTaO3 polycrystalline rare earth ions and the excellent optical properties of lithium niobate described in this paper are of great significance for the research and development of luminescent materials and actual production.In the experiment,a plurality of LiTaO3 polycrystals with different Ho3+,Yb3+ and Tm3+doping concentrations were prepared by high temperature solid phase synthesis.X-ray diffraction patterns,UV-visible absorption spectra,up-conversion fluorescence emission spectra and up-conversion fluorescence lifetimes of double-doped Ho3+/Yb3+,double-doped Tm3+/Yb3+and three-doped Ho3+/Yb3+/Tm3+LiTaO3 polycrystals were tested.The effects of different rare earth ions on the upconversion fluorescence intensity and chromaticity were investigated.The mechanism of upconversion luminescence in this process was analyzed,which provided theoretical basis and experimental guidance for obtaining efficient upconversion white light.According to the X-ray diffraction spectrum test results,it is judged whether the lattice structure of LiTaO3 polycrystals after doping with rare earth ions has changed,and the occupancy of rare earth ions in the crystal is analyzed by combining the moving tendency of the absorption edge in the ultraviolet-visible absorption spectrum.The upconversion luminescence spectra of Ho3+/Yb3+ double-doped and Tm3+/Yb3+ double-doped LiTaO3 polycrystals were tested under the excitation of a 980 nm pump source,and the up-conversion fluorescence lifetime decay curves were tested,combined with the energy levels of Ho3+,Yb3+,and Tm3+ ions.Distribution to analyze the up-conversion mechanism of the fluorescence output of Ho3+/Yb3+ double-doped Tm3+/Yb3+ double-doped LiTaO3 polycrystal system.In this part of the experiment,the single-factor experiment was used to adjust the doping ion concentration,which laid a foundation for realizing the output of up-converted white light in Ho3+/Yb3+/Tm3+ three-doped LiTaO3 polycrystal system.For the Ho3+/Yb3+double doped Tm3+/Yb3+double-doped LiTaO3 polycrystalline sample,we tested the upconversion fluorescence spectrum and upconversion fluorescence lifetime under excitation of a 980 nm pump source.Combined with the energy level distribution of Ho3+,Yb3+ and Tm3+ ions,the up-conversion mechanism between rare earth ions in the double-doped system was analyzed.In this part of the experiment,the single doping concentration variable is used to lay the foundation for the upconversion white light emission in Ho3+/Yb3+/Tm3+tri-doped LiTaO3 polycrystal.On the basis of the double doping experiment,we immediately tested the upconversion fluorescence spectra and upconversion fluorescence lifetime of Ho3+/Yb3+/Tm3+tri-doped LiTaO3 polycrystals,and based on this,the CIE chromaticity coordinates of each sample were obtained.Compare this to standard equivalent energy white light.The effect of changing the concentration of luminescent ions in the material on the upconversion fluorescence intensity and chromaticity of LiTaO3:Ho3+/Yb3+/Tm3+polycrystal system was studied.The upconversion luminescence mechanism in Ho3+/Yb3+/Tm3+-tridoped system was discussed.Based on the previous analysis,we adjusted the concentrations of Ho3+,Yb3+and Tm3+in the material to achieve upconversion white light output of the LiTaO3:Ho3+/Yb3+/Tm3+polycrystalline system excited by a 980 nm pump source.Finally,we get the fluorescence of the output closest to the standard white light emission when the ratio is LiTaO3:0.05 mol%Ho3+/2.0 mol%Yb3+/0.4 mol%Tm3+.