Spectrum-control And Thermal Stability Of MW_1-xMo_xO₄:Eu³⁺(M=Ca²⁺,Mg²⁺,Sr²⁺,Ba²⁺)

White light-emitting diodes（WLEDs）has been widely researched owing to their vast merits of high luminescence efficiency,energy saving,long lifetime and environmentally friendly.It has gradually replaced fluorescent lamps and incandescent lamps as green illumination sources.However,red phosphors excited by near-ultraviolet light are still lacking,and the absence of red light portions leads to low color rendering index of white LEDs,low color temperature,difficulty in meeting lighting requirements,and insufficient thermal stability.The rare earth tungsten molybdate series phosphor has a simple synthesis method,good thermal stability,and a strong charge transfer absorption band in the near ultraviolet light,and can emit red light of about 612 nm.In order to obtain high-efinciency red phosphor,we prepared Eu3+-activated MW1-xMoxO4:Eu3_{M=Ca2+,Mg2+,Sr2+,\Ba2+}phosphors by high-temperature solid phase method,and passed the traces of the second main group Ca2+,Mg2+,Sr2+,and Ba2+.And a lot of doping to explore the effcct of solid solution changes on the luminescence properties of the materials,and the thermal quenching effect of the doped tungsten molybdate phosphors.This paper mainly studies the following aspects:（1）In this experiment,WO3,MoO3,CaCO3.and Eu2O3 were used as raw materials to synthesize calcium tungsten molybdate phosphor by high-temperature solid phase method,and Li+Na+ K+ three kinds of charge compensators were selected for comparison.Li+ Na+ K+ The addition of three charge compensators did not change the structure of calcium molybdate.By comparison of the excitation spectrum and the emission spectrum,it can be seen that the selection of Li+ as the calcium-molybdate charge compensator is the best.（2）On the basis of deternining that Li+ is a charge compensator,the molar percentage（0%,25%.50%.75%,100%）of、MoO42-is changed,so that MoO42-is subsituted for WO42-.The structure of the sample was analyzed by XRD.The change of the ratio of tungsten to molybdenum did not affect the crystal structure of the tungsten molybdate calcium,and it was still a tetrahedral scheelite structure.When the ratio of tungsten to molybdenum is 3:1,the intensity of the emission peak of the sample is the highest.（3）Selecting the second main group Mg2+,Sr2+,Ba22+ to replace Ca2+,to explore the effect of solid solution composition change on the luminescence properties of red phosphor.The structure of the sample was analyzed by XRD.The addition of Sr2+,and Ba2+ did not have the lattice of the matrix material.due to the different ionic radii of Mg2+,Ca2+,Sr2+ and Ba2+,the sample of the tungsten molybdate system produces a significant blue shift phenomenon at the peak of the excitation peak of λem=612.The color coordinates of each sample are close to the ideal red phosphor.The fluorescent pink coordinates of the doped Ca2+ tungsten molybdate are（0.640,0.352）and are close to the NTSC standard value（0.67,0.33）.,This shows that the color of the sample we prepared is relatively high.And the thermal quenching phenomenon of the sample was analyzed.The thermal stability of Ca2+ at 150℃ is 72.70%at 25℃,and the thermal stability was better.The luminescence intensity of Mg2+ showed a positive correlation with temperature.It shows obvious thermal quenching and good thermal stability.（4）While doping a small amount of Mg2+,the excitation peak of the sample forms a new broadband spectrum at 352 nm,so that the luminescent color is closer to the ideal red when the composite excitation light and the emitted light illuminate.The luminescence heat quenching phenomenon of the slightly doped Mg2+ phosphor is serious.（5）By comparing the luminescence intensity,thermal stability and color purity,CaEu0.1Li0.1（WO4）0.75（MoO4）0.25 was selected as the matrix material,and the second main group of trace Mg2+,Sr2+,Ba2+ was substituted for Ca2+,and the changes of trace solid solution were investigated.The effect of red phosphor on the thermal stability is found by the comparison of excitation spectrum and emission spectrum.The red light emission is the strongest when the doped Sr2+ is excited at 294 nm and the concentration is 1%.The color coordinates（0.643,0.350）of the doped 10%Mg2+ are close to the NTSC standard values（0.67,0.33）.The luminescence heat of Sr2+ doped CaEu0.1Li0.1（WO4）0.75（MoO4）0.25 phosphor is better.When the temperature is 150℃,the relative luminescence intensity of 3%Sr2+ doping is 93.87%.