Preparation And Optical Properties Of Rare Earth Doped Silicate Luminescent Materials

As we all know,the application of luminous materials is very wide and has penetrated into the production and life of all aspects of human society.In recent years,more and more scholars have developed a variety of new luminescent materials,constantly expanding the content of the existing luminescent material system.In this paper aiming at the silicate system phosphors bearing substrate,using high temperature solid phase method,the preparation of a series of new type of phosphor powder samples,including the selection of specific silicate substrate have Li2CaSiO4,Na2CaSiO4,specific rare earth ions doped with Pr³⁺,Dy³⁺,Y³⁺,and adopt the single or double kinds of rare earth ions doped rare earth ions doped way,Li₂CaSiO₄:Pr³⁺,Na₂CaSiO₄:Pr³⁺,Li₂CaSiO₄:Pr³⁺/Dy³⁺and Na₂CaSiO₄:Pr³⁺/Y³⁺phosphors were successfully prepared.Then,by detecting the XRD pattern,emission and excitation spectra and fluorescence attenuation curves of the samples,the fluorescence lifetime,color coordinates and color temperature of the samples were calculated to analyze the specific spectral characteristics of the samples,and the factors affecting the luminous performance of the samples in the experiment were further studied to continuously optimize the preparation process of the samples.(1)(M)₂CaSiO₄:Pr³⁺silicate phosphors(M=Li,Na)The basic spectral characteristics of Li2CaSiO4:Pr3+phosphors:at 598nm monitoring wavelength,the excitation spectrum is mainly located in the blue region,which is divided into three continuous narrow bands,with the central positions at449nm,477nm and 488nm,respectively,which belong to the³H₄?³P₂,³H₄?³P₁,³H₄?³P₀transition of Pr³⁺.Under the monitoring wavelength of488nm,its emission spectrum is mainly located in the orange-red light region,and the emission peaks at 598nm,619nm and 651nm are higher,which are sequentially attributed to the transition of ³P₁?³H₆,³P₀?³H₆,³P₀?³F₂of Pr³⁺.The basic spectral characteristics of Na₂CaSiO₄:Pr³⁺phosphors:at 598nm,the main excitation peak is located at 488nm,which is attributed to the ³H₄?³P₀transition of Pr³⁺.Similarly,the characteristic excitation peak of Pr³⁺also exists at449nm and 477nm,but the intensity is very weak.At 488nm,the main emission peak is located at 598nm,which is attributed to the ³P₁?³H₆transition of Pr^3+.At611nm and 652nm,there are weak emission peaks,which are attributed to the³P₀?³H₆,³P₀?³F₂transition of Pr³⁺.In addition,it has a narrow-band emission peak at 640nm under the excitation of 522nm monitoring wavelength,which are attributed to the ³H₅?³P₁and ³P₀?³F₂transition of Pr³⁺,respectively.Comparing the basic spectral properties of Li₂CaSiO₄:Pr³⁺phosphors and Na₂CaSiO₄:Pr³⁺phosphors,it is found that the excitation and emission spectra of Li₂CaSiO₄:Pr³⁺phosphors are similar to some extent due to the different effects of matrix crystal field on Pr³⁺,but the overall peak shape is very different.As for(M)₂CaSiO₄:Pr³⁺silicate phosphors(M=Li,Na),various factors(doping concentration,temperature,holding time,flux,Charge compensating agent)that affect the luminescence properties of(M)₂CaSiO₄:Pr³⁺silicate phosphors(M=Li,Na)have also been studied.A series of preparation conditions and methods for improving the luminescence properties of(M)₂CaSiO₄:Pr³⁺silicate phosphors have been obtained.(2)Li₂CaSiO₄:Pr³⁺/Dy³⁺silicate phosphorThe Li₂CaSiO₄:Pr³⁺/Dy³⁺double rare earth ion doped phosphors were synthesized experimentally.The co-doping of Pr³⁺and Dy³⁺could be used as the luminescence center,so that the Li₂CaSiO₄:Pr³⁺/Dy³⁺phosphors could contain the characteristic excitation and emission peaks of Pr³⁺and Dy³⁺at the same time.In addition,the experimental results by adjusting the Pr³⁺and Dy³⁺doping ratio,found Dy³⁺add exacerbate Pr³⁺clusters effect,thereby enhancing the self-excited effects between the Pr³⁺,449nm wavelength monitoring,the blue light emission peak at488nm with other orange light range emission peak intensity ratio gradually reduced,greatly changed the sample overall emission peak form.After the calculation and characterization of the sample color coordinates,it is known that the luminescence color of Li₂CaSiO₄:Pr³⁺/Dy³⁺silicate phosphor can be adjusted in the orange region by controlling the doping ratio of co-doped ions Dy³⁺and Pr³⁺(1%).(3)Na₂CaSiO₄:Pr³⁺/Y³⁺silicate phosphorNa₂CaSiO₄:Pr³⁺/Y³⁺double rare earth ion doped phosphors were synthesized.Compared with the single doped Pr³⁺phosphors,the excitation and emission peak positions and shapes of the two phosphors were basically consistent.When the co-doped 0.3%Y³⁺increased the overall emission intensity of Na₂CaSiO₄:2%Pr³⁺to about 1.3 times,the fluorescence lifetime was also enhanced.