Synthesis And Upconversion Properties Of Lanthanide-doped NaYF₄/PMMA

The upconversion （UC） phosphors have been investigated extensively due totheir potential applications in some fields, such as materials science and bioscience.Especially, the three-dimensional （3D） volumetric optical displays are opening up anew period for the development of upconversion utility. The ability to synthesizetransparent upconverting polymer nanocomposites can facilitate the manufacture ofthe three-dimensional （3D） volumetric optical displays.In this paper, we have synthesized size-and phase-controlled lanthanide-doped（Ho, Tm, Yb, Ce）NaYF₄nanocrystals by hydrothermal method. In order to obtainsize-and phase-controlled lanthanide-doped （Ho, Tm,Yb, Ce）NaYF₄nanocrystals,we have investigated the reaction time, reactant temperature, concentration, and F-/RE³⁺in hydrothemal method which can influence the size and phase of lanthanide-doped （Ho, Tm, Yb, Ce）NaYF₄nanocrystals. Lanthanide-doped （Ho, Tm, Yb, Ce）NaYF₄nanocrystals can emit different colour luminesence through changing thekind of rare earth and percentage. The energy transfer properties of theseLanthanide-doped （Ho, Tm, Yb, Ce） NaYF₄nanocrystals were investigated in detail.In this work, we synthesized a series of NaYF₄: Yb, Ho, Ce（Tm）/PMMAnanocomposites by in situ bulk polymerization.In this paper, we get the following conclusions. When the reactiontemperature for180℃, reaction time for12h, rare earth ions concentration of0.033mol/L, F-/RE³⁺for5, we got rare earth doped NaYF₄spherical particles with100nm. By changing the type of rare earth doped and the proportion of rare earthions, we obtained rare earth doped NaYF₄powder which can emit different colors.NaYF₄:1%Ho,10%Yb powder emit green color; NaYF₄:2%Ho, x%Tm（x=0.5,1,1.5,2）,10%Yb powder emit green, weak green, weak yellow green, weakyellow respective ly; NaYF₄:2%Ho,0.5%Tm, x%Ce（x=0,5,7,10,）10%Yb emitgreen, white, yellow, reddish yellow; NaYF₄:1%Ho,1%Tm,15%Ce, Yb20%emit bright white; NaYF₄:1%Ho,1%Tm,7%Ce,20%Yb powder and NaYF₄:1%Ho,1%Tm,10%Ce,20%Yb powder emit approximate white color.We dealt the Lanthanide-doped （Ho, Tm, Yb, Ce）NaYF₄nanocrystals withsilane coupling agent. We utilized modified treatment to achieve high dispersionquanlity of the nanopartic les in polymeric medium. We investigated the influence ofmodified inorganic particles to NaYF₄: Yb, Ho, Ce（Tm）/PMMA nanocomposites.The conclusion is that the luminescent properties of modified NaYF₄: Yb, Ho,Ce（Tm）/PMMA nanocomposites reduce. Through investigating the influence ofdifferent content （1%,2%,3%） of the rare earth doped NaYF₄on the performance of the composite material, the study found that with the increases of content, thelight transmittance of the rare earth doped NaYF₄/PMMA composite decrease, butthe stability increase. Even if the content is3%, light transmittance still can reach67%. Finally, obtain the rare earth doped NaYF₄/PMMA composite materials withhigh light transmittance and stability.