Synthesis And Optical Properties Of Photolumiescence Materials Based On Molybdate

In this study, the AgLaMo2O8:Pr3+ and BaLa2(MoO4)4:Pr3+ andCaMoO4:Eu3+/Na+phosphorswitharatherstrongf‐ftransitionexcitationintheUVandvisibleregionwerefabricatedbydifferentsynthesismethods.Inaddition,thestructures, morphologies and optical properties of as‐prepared products werethoroughlycharacterizedbyusingX‐raypowderdiffraction(XRD),Scanningelectronmicroscopy(SEM),Fieldmissionscanningelectronmicroscopy(FESEM),Transmissionelectron scanning microscopy (TEM), and Fluorescence spectroscopy (PL),respectively.Here,theeffectsofthesynthesismethodsandreactionconditionsonthestructure,morphologyandopticalpropertiesofas‐preparedsampleshavebeenstudied. Finally, the optimal preparation conditions, the related mechanisms ofsynthesis and luminescence mechanism were explained and discussed. The mainresultsaresummarizedasfollowing:1) The red phosphors AgLaMo2O8:Pr3+ were prepared by conventionalsolid‐statereactiontechnique.TheeffectsofsynthesistemperatureandPr3+dopedconcentrationontheluminescentpropertiesandcrystalstructuresofredphosphorshave been investigated. The detailed results indicate: The diameter of phosphorparticlesislessof1µm.InthePLspectraofas‐preparedsamples,theoptimalvalueofPr3+concentrationis3%andtheoptimizedtemperatureis1100Cforthestrongestemission.Theexcitationwavelengthranging430nm–500nminthevisibleregioncoverstheavailablerangeofcommercialblueLED.Moreover,thePLspectrashowsasatisfactoryredperformanceat649nmwiththeFWHMof3nmandthe CIE chromaticity coordinates is (0.685, 0.315), indicating this phosphor caneffectivelyimprovecolorrenderingindexofwhiteLED.2)The deep red phosphors BaLa2(MoO4)4:Pr3+ have been prepared by thesame solid‐state reaction technique. The effects of reaction conditions on theluminescent properties and crystal structures of compound have also beeninvestigated.Itsphysicalandchemicalpropertiesandphotoluminescencearesimilarwith AgLaMo2O8:Pr3+. But the alkali metal were introduced into the phosphor system BaLa2(MoO4)4:Pr3+ by adding appropriate amounts of alkali halide in thepreparing.Thedopingalkalimetalionscanincreasethenoncentrosymmetryofthecrystalstructureofmolybdate.TheredemissionintensitywasenhancedsignificantlybydopingalkalimetalintheBaLa2(MoO4)4:Pr3+phosphorsystemandtheemissionintensityis1.35timescomparedwiththatofundopedalkalimetal.3)The Eu3+/Na+‐codoped CaMoO4 microphosphors were successfullysynthesizedatlowtemperatureviaafacilehydrothermalmethodinsurfactant‐freeenvironment.SEM,FE‐SEMandTEMimagesoftheCaMoO4productspreparedatpH1.5,150°Cfor6hrevealed3Dflake‐ballandflake‐disksuperstructures,composedofdenselypackednanoflakes.TheformationmechanismofCaMoO4microstructureswas discussed in detail based on the hydrothermal temperature. Meanwhile, theaffect of pH value and Ca source on the morphology and photoluminescencepropertieswerealsoinvestigated.Room‐temperaturephotoluminescencepropertiesofmicrosizedCaMoO4:Eu3+/Na+phosphorswerestudied.Itsexcitationwavelengthsrangingfrom350to530nmintheUVandvisibleregionssignificantlyextendtheexcitation region of phosphor materials. Comparison with Eu3+‐doped sample,Eu3+,Na+‐codoped CaMoO4 samples play more stronger photoluminescenceintensity,whereNa+actsasachargecompensator.ThiscanbeexplainedbychargecompensationinthephosphorsystemCaMoO4:Eu3+/Na+.ThePLspectraindicatetheproductsemitbrightredfluorescenceandhavehighcolorpurity.