Preparation And Photoluminescence Properties Of Rare Earth Ions Doped Typical Luminescence Material Upon120-980Nm Excitation

Due to the important application in many fields, rare earth ions doped luminescence materials upon120-980nm excitation have been studied widely. First, the luminescence materials under vacuum ultraviolet (VUV) excitation can apply to the plasma display panels (PDPs) and Hg-free lamps. Especially in the three-dimensional (3D) display arisen in recent years, they show strong advantages due to the characteristics of higher response speed. Thus, more requirements are also presented for the qualities of VUV phosphors such as luminous efficiency, color purity, decay lifetime, stability, and so on. On the other hand, the mechanism of luminescence upon VUV excitation is not very clear for the time being, which will lead to blindness easily when exploring new luminescence materials. So investigation on the luminescence mechanism is also an important issue. Second, Near-UV excited luminescence materials can apply to white light-emitting diodes, and some requirements of characters are also put forward correspondingly. Firstly, the luminescence materials should have strong absorption in near-UV region. Secondly, high brightness is needed. Thirdly, high stability is also included. Third, the luminescence materials for near infrared (NIR) quantum cutting (QC), which converts one phonon with high energy into two or multiple NIR phonons, can help to promote the efficiency of crystalline Si solar cell. Fourth, the upconversion (UC) materials use NIR light as excitation source, which occurs by converting two or multiple phonons with low energy into one phonon with high energy. These materials have strong advantages in biological labeling to reduce tissue damage. Based on the above reasons, we designed and preprared some luminescence materials under120-980nm excitation, and studied their luminescence properties. The main points are listed below:1. Ln3+(Ln=Eu, Tb, Sm, Ce, Tm) and Mn2+doped Ca8MgGd(PO4)7, Ca10K(PO4)7, Ca3(PO4)2and SrY2O4phosphors were prepared by high temperature solid-state reaction, and their photoluminescence spectra upon VUV excitation were measured. The brightnesses of Tb’+doped CagMgGd(PO4)7and Ca3(PO4)2are comparable to that of the commercial green Zn2SiO4:Mn2+phosphor, with shorter decay lifetimes than Zn2SiO4:Mn2+which has a stronger advantage for the application in3D display. Ce3+-Tb3+-Mn2+tri-doped CagMgGd(PO4)7phosphor could realize white emission under147run excitation, which has an important application in Hg-free lamps; Ln3+(Ln=Eu, Sm, Tb, Tm, Ce) actived Ca10K(PO4)7samples have potential application in multicolor display due to their different emitting colors. Low quenching concentration of Tb3+was found in Tb3+activated SrY2O4under147nm excitation, which is due to the short Y-Y distance in SrY2O4host. But the f-d transition of Tb3+in this phosphor was found to lie in the much lower energy region, owing to the strong crystal field in SrY2O4host. In addition, Eu3+activated YPO4was synthesized by a hydrothermal route, in which spherical and rod-shaped morphologies were obtained under acidic and alkaline condition, respectively. Upon147nm excitation, the Eu3+emission peaks are observed, in which the red5D0-7F2transition is predominated, resulting in a good color purity. After annealing, the luminescence intensity is enhanced obviously, originating from the increased crystallinity and particle growth.2. Eu3+activated Ca10K(PO4)7and Ba3Bi(PO4)3phosphors were synthesized by high temperature solid-state reaction, and their photoluminescence properties upon near-UV excitation were studied. Both phosphors exhibit characteristics Eu3+emission with good red color purity and high brightness of about twice as much as that of the commercial red Y2O3：Eu3+phosphor. And when doping Mo6+into Ca10K(P04)7, the brightness is enhanced largely, mainly due to the slightly variety of the excited energy levels in the compound, leading to the red-shift of the absorption edge.3. SrY2O4:Eu3+phosphor was prepared by both solid-state reaction and sol-gel method. The location of Eu3+in the host lattices was discussed, and luminescence related with defects of host was found in SrY2O4:Eu3+prepared by solid-state reaction, whereas it was not detected in the sample prepared by sol-gel method. This result may be due to the anti-defects in the sample prepared by solid-state reaction. Upon147nm excitation, the SrY2O4:Eu3+phosphor prepared by sol-gel method demonstrates higher brightness compared with that by solid-state reaction, owing to the former sample has more regular morphology, which reduces the disadvantage scattering of the incident VUV light.4. Y6O5F8:Ln3+(Ln=Yb, Er, Ho) phosphors were prepared by hydrothermal method, and their photoluminescence properties under near-UV, blue and NIR light were investigated. With the additives of CTAB, PVP and EDTA, hollow hexagonal prisms, microbundle gatherings by rods and solid hexagonal prisms were abtained. Under near-UV and blue light excitation, the NIR emission with QC phoemenon was observed. Under450nm excitation, a modified equation for QC efficiency was proposed, and the characteristics of the NIR emission spectra were interpreted by anti-energy-transfer. Under980nm excitation, Y534O5F8:10%Yb3+ 1%Er3+and Y5.34O5F8:10%Yb3+,1%Ho3+samples exhibit intense green and red emissions, respectively.5. SrGd2O4:Ln3+(Ln=Yb, Tm, Er, Ho) and Ca3(PO4)2:Ln3+，Na+(Ln=Yb, Tm, Er, Ho) UC materials were synthesized by solid-state reaction. Upon980nm excitation， Yb3+-Er3+Yb3+-Tm3+and Yb3+-Ho3+doped SrGd2O4samples show yellow, blue and green emissions, respectively. And in Yb3+-Er3+-Tm3+tri-doped SrGd2O4sample, the cross-relaxation process of3H4(Tm)+4I13/2(Er)â†'3H6(Tm)+4S3/2(Er) is found, which can be used to interpret why the green emission of Er3+in this tri-doped sample is stronger than that in the Yb3+-Er3+co-doped SrGd2O4sample. Yb3+-Er3+, Yb3+-Tm3+and Yb3+-Ho3+doped Ca3(PO4)2samples exhibit yellow-green, blue and red emissions, respectively, and Yb3+-Er3+-Tm+3-Ho3+quadric-doped Ca3(PO4)2sample can realize white emission.6.(Y, Gd)VO4:Ln3+(Ln=Eu, Yb, Er, Ho) samples were prepared by hydrothermal method, and (Y, Gd)VO4:Ln3+@nSiO2@mSiO2(Ln=Eu, Yb, Er, Ho) samples were further obtained via a TEOS hydrolysis method. For (Y, Gd)VO4, monodisperse regular ellipsoid-like hollow particles were obtained. By adjusting the reactant concentrations, the control of particle size was realized, but the hollow characteristic was not affected. For (Y, Gd)VO4:Ln3+@nSiO2@mSiO2(Ln=Eu, Yb, Er, Ho), the core-shell structure with mesoporous SiO2shell was obtained. Under980nm excitation, Y0.78VO4:0.2Yb3+,0.02Er3+and Yo.78V04:0.2Yb3+,0.02Ho3+samples exhibit green and red emissions, respectively. By cell cytotoxicity assay, the samples show good biocompatibility. In the drug-release experiment, fast release appears in the initial stage, but it slows in the later stage, and the final release is completed beyond30h.