Luminescence Properties Of NaTaOGeO₄:Mn²⁺ Co-doped Pr³⁺ Or Tb³⁺ System Phosphors

White light emitting diodes(WLEDs)are regarded as the new generation il-luminate light sources and have been widely applicated in many fields due to the properties of long lifetime,high photoluminescence efficiency and less pollution.At present,WLEDs are prepared by ultraviolet and near ultraviolet excitation trichro-matic phosphors.However,this kind of method needs a mixture of polyphase phos-phors.But the regulation of the ratio of polyphase phosphors seriously affects the color reproduction.In addition,the complicated preparation process and high cost factors limit the development and application of such phosphors.Therefore,the preparation of a novel and efficient single-phase white light emitting material has become a hot topic in the field of solid-state lighting.A novel single-phase tunable-emission phosphors,including NaTaOGeO4:Mn2+,Pr3+ and NaTaOGeO4:Mn2+,Tb3+,have been prepared by high-temperature solid-reaction in this paper.The crystal structure,photoluminescence properties,decay time of the sample and the thermal stability were investigated in this thesis.The result of X-ray diffraction indicates that doping Pr3+ ions,Tb3+ ions and Mn2+ ions has no influence on NaTaOGeO4 crystal structure.The excitation spectra of NaTaOGeO4:Mn2+ phosphors monitored at 576 nm consists of two peaks at 228 nm and 248 nm which attributed to the host matrix and Mn2+ ? O2-charge transfer transition.The emission spectra excited at 248 nm exhibits a strong band at 576 nm which is assigned to the 4T1?6A1 transition of Mn2+ ions,and the broad band from 350 nm to 500 nm is the emission of host matrix.The excitation spectra of NaTaOGeO4:Pr3+ phosphors consists of a broad band at 277 nm which assigned to the 4f5d state excitation transition of Pr3+ ions.The emission spectra excited at 277 nm shows blue-green emissions mainly originated of 3P0?3H4(492 nm and 498 nm).By doping different concentration of Pr3+ ions to NaTaOGeO4:Mn2+,a color tunable phosphor NaTaOGeO4:Pr3+,Mn2+ were obtained.And the spectra confirms the existence of energy transfer from Mn2+ ions to Pr3+ ions.The emission spectra of NaTaOGeO4:Tb3+ excited at 244 nm exhibit sharp blue-green emission peaks at 380,413,436,492 and 544 nm,which attributed to the 5D3?7FJ and 5D4?7FJ(J = 6,5,4)transition of Tb3+ ions,respectively.The emission spectra of NaTaOGeO4:Tb3+ excited at 277 nm mainly shows green emissions at 492 nm(5D4 ? 7F6)and 544 nm(5D4 ? 7F5).By doping differen-t concentration of Tb3+ ions to NaTaOGeO4:Mn2+,a color tunable phosphor NaTaOGeO4:Tb3+,Mn2+ were obtained.It confirms the existence of energy trans-fer from Tb3+ ions to Mn2+ ions from the decay time curves.Meanwhile,it can be demonstrated that the energy transfer mechanism is the electric multipolar in-teractions between Mn2+ ions alcording to the mechanisms for nonradiative energy transfer.