Preparation And Luminescent Properties Of Rare Earth Ion Doped Molybdate Phosphor

White LEDs are regular as widely regarded as a new generation of solid-state lighting source that can replace high-fluorescent lamps?CFDS?,because it has many unique properties,like high reliality,long life,low energy consumption,greem emvirnmental protection.Fluorescence conversion is the main way to realize white LEDs.Along with the development of research and application,the low color rendering index and high color temperature of white LEDs greatly limits the development and application of high-efficiency white LEDs.Therefore,the research focus at present stage is studied can be effectively by near ultraviolet light with high luminous efficiency,and the good stability of red phosphors.Molybdate have low synthesis temperature,stable performance,molybdenum sulfate can effectively absorb energy and transfer energy to the luminescence center,etc.,which is a good phosphor matrix.In this paper,molybdate red phosphors of KGd?Mo O₄?₂,Sr Y₂?Mo O₄?₄ and K₅Y?Mo O₄?₄ systems are prepared by high temperature solid.?1?The preparation process of KGd?Mo O₄?₂:Sm³⁺red phosphor powder was explored,which determined that the calcining temperature was 800 ^oC and the soaking time is 3h.The influence of activator ion Sm³⁺concentration on KGd?Mo O₄?₂:Sm³⁺red phosphor luminescence performance and the introduction of sensitized ion Bi³⁺on the luminescence performance of the phosphor was studied.The results showed that the luminescence intensity is the highest when doped amount of Sm³⁺ion is x=0.06.Excitation spectra shows the phosphor is excitated by the n-UV LED,and the maximum emission peak is located at 646 nm.The incorporation of Bi³⁺in KGd?Mo O₄?₂:Sm³⁺red fluorescence is a kind of excellent sensitizing ions,it can effectively broaden and strengthen in the excitation spectrum of ultraviolet to the blue area,and effectively improve the luminous intensity,the optimal doping amount of Bi³⁺y=0.07,KGd?Mo O₄?₂:Sm³⁺phosphor luminescent intensity improved 2.4 times.?2?The high ligand molybdate Sr Y₂?Mo O₄?₄ red phosphors were prepared by high temperature solid phase method.In this chapter,luminescent properties of doped Sm³⁺ions of Sr Y₂?Mo O₄?₄:Sm³⁺were studied.and luminescent properties of this phosphor are greatly improved by doping the different types of oxyacid root(BO₃^3-,PO₄^3-).The experimental results showed that the optimal excitation and emission peaks of Sr Y₂?Mo O₄?₄:Sm³⁺red phosphor were located at 407nm and 648 nm respectively,and the optimal doping amount of Sm³⁺is x=0.05.The CIE coordinate of the experimental sample is?0.600,0.395?,which showed a red light.A small amount of oxyacid root(BO₃^3-,PO₄^3-)didn't change phase structure of the Sr Y₂?Mo O₄?₄ matrix,the BO₃^3-and PO₄^3-in the form of solid solution in Sr Y₂?Mo O₄?₄ crystal,through the test results by XRD,SEM and IR spectra,and can increase the crystallinity of the sample,but excess oxyacid root can make the structure distortion and even be destroyed.The addition of oxygen-containing acid can effectively improve the absorption capacity of phosphor in ultraviolet region.And the luminescent intensity of phosphor increases greatly,which BO₃^3-the best doping amount of y=0.2,luminous intensity can be improved about 2.2 9 times.PO₄^3-the optimal doping amount is y=0.15,and the luminous intensity can be increased by 2.56 times.At the same time,the color coordinates of the sample will be shifted to red.?3?K₅Y?Mo O₄?₄ red phosphors of different rare earth ions(Eu³⁺,Sm³⁺)were prepared by high temperature solid phase method.For K₅Y?Mo O₄?₄:Eu³⁺red phosphors,There is a strong absorption of 395nm near ultraviolet light and 466 nm blue light,which indicated that K₅Y?Mo O₄?₄:Eu³⁺red phosphors can excited by near-UV LED chip and blue LED chip,and emitting the red light locate at 612 nm,the optimum doping amount of x=0.2,the chromaticity coordinates is?0.656,0.343?.And then,the concentration quenching phenomenon will occur w hen increased again the doping amount of Eu³⁺ions.The mechanism of concentration quenching due to the interaction between the electric dipole-electric dipole of adjacent Eu³⁺.For K₅Y?Mo O₄?₄:x Sm³⁺red phosphors,there is a series of excitation peaks at 340 nm to 500 nm,and the strongest peak is near UV light of 407 nm.Main emission peak at 561 nm,561 nm and 646 nm,the optimum doping amount of Sm³⁺ions is x=0.05,continue to increase the amount of doping concentration quenching phenomena will happen,The concentration quenching mechanism of d-d interaction.