Preparation Of Ce³⁺,Tb³⁺,Sm³⁺ Doped Shelf Like Silicic Acid Luminescent Materials （AB） SiO₄ （A=Ba,Na,Li,B=Al,Sr） And The Regulation Of Photoluminescence Properties

In this paper,we investigated the three kinds of silicate luminescent materials including BaAl₂Si₂O₈,NaAlSiO₄ and Li₂SrSiO₄ doped with variety of rear earth.Methods of material synthesis,crystal structure,luminescence properties,fluorescence lifetime,color purity,energy transfer mechanism and color regulation are discussed in detail.Characterized by using powder X-ray diffractometer（XRD）,stable/transient fluorescence spectrometer,thermal quenched analyzer,etc.The main research contents include the following three aspects.1.The blue phosphors(BaAl₂Si₂O₈:Tb³⁺,Ce³⁺)were prepared by high temperature solid-state reaction.The spectral characteristics and the luminescence mechanism of Tb³⁺,Ce³⁺doping and Tb³⁺/Ce³⁺co-doped BaAl₂Si₂O₈ powders were studied both experimentally and theoretically,and the energy transfer process of Ce³⁺→Tb³⁺in combination with relevant theories also explained.It shows the luminescent powders were characterized in detail in terms of the crystal structure,band properties and chrominance.The crystal structure of BaAl₂Si₂O₈ agreed with the standard structure.The incorporation of Ce³⁺has not only improved the effective excitation of the BaAl₂Si₂O₈:Tb³⁺in the region of near ultraviolet light,but also greatly increased the luminous intensity of BaAl₂Si₂O₈:Tb³⁺.In addition,we explained the form of the energy transfer between the two ions.The energy transfer efficiency reached 76.04%.The achieved material is expected to be applied to ultraviolet white light-emitting diodes（UV-WLEDs）in green powder.2.A series of color tunable fluorescent materials with Ce³⁺and Sm³⁺co-doped NaAlSiO₄ were prepared by high temperature solid-phase method.Under the excitation of 325 nm,NaAlSiO₄:Ce³⁺,Sm³⁺shows strong blue emission located at444 nm and orange-reddish emission centered at 563 nm,601 nm,648 nm and 712nm,stemming from the characteristic emission for 4f-5d transition of Ce³⁺and ⁴G_5/2→⁶H_J（J=5/2,7/2,9/2,11/2）transition of Sm³⁺,respectively.In addition,we studied the detailed energy transfer process between Ce³⁺and Sm³⁺and found that it belonged to dipole-dipole resonance energy transfer.Furthermore,we noted that the white light emitting from the Ce³⁺,Sm³⁺co-doped phosphors with the color coordinate（x=0.313,y=0.283）can be observed under 325 nm excitation,which is close to the ideal white light（x=0.33,y=0.33）.The results indicated that this phosphor has a potential application as a single-phased alumino-silicate phosphor for UV-WLEDs.3.Li₂Sr_1-x-x Ba_xSiO₄:Ce³⁺（x=0,0.01,0.03,0.05,0.07,0.09,0.1）were synthesized,and the crystal structure and luminescence performance were characterized by powder X-ray diffraction and photoluminescence spectra.I also studied the effects of Ba²⁺ion doping on its crystalline structure and its luminescent properties.Incorporation of the Ba²⁺ion into the crystal structure caused to the shifts of the X-ray spectrum of the matrix material.In terms of luminescence properties,the intensity of the characteristic emission peak of Ce³⁺ion was enhanced and then weakened,and the optimal concentration was 0.03mol.The incorporation of Tb³⁺ions resulting to the color tunability of the materials.