Preparation And Luminescence Properties Of LanbO₄-based Rare-earth-doped （Ln=Dy,Tb,Eu,Sm）

In this dissertation, we mainly focus on the rare earth doped LaNbO4which issuitable under254nm UV excitation. We prepare single matrix emitting white lightfluorescent material, which is single doped by rare earth Dy³⁺or co-doped by Dy³⁺withTb³⁺、Eu³⁺、Sm³⁺prepared by high-temperature solid-phase synthesis. The host latticestructure and the luminescent properties of Dy³⁺single-doped samples are detailedstudied, by X-ray diffraction, photoluminescence excitation and emission spectra,scanning electron microscopy （SEM）, fluorescence microscopy and other means. Thespectral tailoring by rare earth co-doped can achieve adjustable color temperature whitelight fluorescent material. To optimize the luminescent properties of the sample, we studyin detail the influence of flux on the changes in the emitting distribution of the LaNbO4-based luminescent materials. The main contents as follow:Using high-temperature solid phase, we achieve the single sample emitting whitelight new phosphors, which select monoclinic LaNbO4as matrix through rare earth ionsdoped.The studies of La31-xNbO4: Dy+x（0.01-0.1）photoluminescence properties showthat La1-xNbO4: Dy³⁺xcan be efficiently excited with UV. Peak at410nm broadband blueemission from Nb5+-O2-charge transfer band of the matrix, yellow luminescence emissionline at575nm from Dy³⁺ions characteristic emission （4F69/2�'H13/2transition）.Thecombination of broadband blue emission and the linear yellow emission can observe abright white light. With the increase of the concentration of Dy³⁺, the matrix chargetransfer band blue emission intensity gradually decreases, while the Dy³⁺characteristicemission （4F69/2�'H13/2transition） gradually increases, which lead to the luminescencechanges. To enrich the emission spectrum, we incorporate the rare earth ions of Tb³⁺tothe sample of La1-xNbO4: Dy³⁺x.In the excitation of254nm ultraviolet, we can observethe rare earth Dy³⁺ion575nm（4F6+9/2�'H13/2transition） and Tb3ion545nm （5D74�'F5transition）sharp characteristic emission peaks from the photoluminescence spectra of thesamples. We further incorporate rare earth ions Eu³⁺or Sm³⁺in co-doped samples, so thatwe can observe613nm （5D0�'7F2transition） characteristic emission peak of the rare earthEu³⁺ion in the red zone,as well as the647nm（4G65/2�'H7/2transition） characteristicsemission peak of rare earth ion Sm³⁺.By co-doped and multi-doping, we greatly enrichthe luminescence spectra. In the near ultraviolet/ultraviolet excitation,we can see thatmulti-doped sample presents a multi-color light-emitting phenomenon. We use H3BO3orNaF as the flux to synthesis samples. The fluorescence microscopy analyses show that ifwe select NaF as the flux, the samples particle uniformity and luminous performancehave greatly improved. The flux has a very important role for the optimization of theluminescent properties of the phosphor.