【作者】 周永勤；

【导师】 余锡宾；

【作者基本信息】 上海师范大学 ， 应用化学， 2011， 硕士

【摘要】 本论文采用不同的化学方法分别合成了三种基于钼酸盐的发光材料:可紫外和可见蓝光区域激发的AgLaMo2O8:Pr3+荧光粉、BaLa2(MoO4)4:Pr3+荧光材料和纳米组装的CaMoO4:Eu3+/Na+荧光粉。应用X‐射线粉末衍射(XRD)、荧光光谱(PL)、场发射扫描电子显微镜(FESEM)、扫描电子显微镜(SEM)、透射电子扫描显微镜(TEM)等测试手段分别对材料的结构、形貌和性能进行表征,研究了不同反应条件对所得材料的晶型结构、形貌以及光学性能的影响,得到了最佳制备工艺条件,并对相关合成机理和发光机理进行了解释和讨论。主要研究内容叙述如下:1.通过一种简便的高温固相法成功合成了AgLaMo2O8:Pr3+红色荧光粉,讨论了合成荧光粉的最佳工艺条件,并研究了不同反应条件对物质结晶性能和发光性能的影响。通过各项表征结果可知:该发光材料粒径在1µm以下,在430～500nm的光谱区间有很好的吸收,与商业蓝光LED的发射波长相一致,并在以649 nm为中心的红光区有很强的发射,其发光强度约是商业红粉Y2O2S:Eu3+发光强度的3.2倍。此外,发光性能受到反应温度和激活剂掺杂浓度的影响,镨离子最佳摩尔浓度是3%,最优化的温度是1100℃。在649 nm处的半峰宽仅有3 nm,红色纯度很高,其色坐标指数是(0.685,0.315),表明钼酸银镧掺镨红色荧光体能有效地改善白光LED的显色性。2.同样利用简单的固相反应法制备BaLa2(MoO4)4:Pr3+红色荧光材料,研究了其在各制备条件下的影响,其物理化学性能与之前制备的AgLaMo2O8:Pr3+相似。但在制备过程中加入碱金属卤化物,从而在材料中引入了碱金属离子,成功地制备了碱金属掺杂的BaLa2(MoO4)4:Pr3+荧光材料。其中,碱金属的引入加大了钼酸盐离子晶体结构的非对称性。引入碱金属后,荧光材料的发光性能得到了大幅度地改善,是掺杂前BaLa2(MoO4)4:Pr3+荧光材料发光强度的1.35倍。3.利用一种方便,环保,无任何有机添加剂的低成本的水热方法制备了自组装多级结构CaMoO4:Eu3+,Na+荧光体。由SEM,FE‐SEM和TEM表征照片知:在150°C‐ 6 h‐ pH1.5的反应条件下合成的钼酸盐样品颗粒平均直径为5µm,其结构是纳米片一层一层叠加而成的三维圆球和圆盘状。我们通过温度实验探讨了多级结构的形成机制,利用Ostwald熟化和自组装聚集机制对晶体生长进行了解释。此外,本章中还研究了pH值和钙源等反应条件对产物形貌和分散性的影响,得出了pH值在1.5和CaNO3做钙源时为这些材料的最佳条件。在激发光谱图中,激发波长范围从350到530nm的紫外和可见光区,显著的扩展了发光材料的应用区域。同时,该钼酸钙荧光材料中存在的少量Na+离子能够起到电荷补偿的作用,提高了材料的发光性能。发射光谱表明,样品发出了明亮的红色荧光,且具有较高的色纯度.更多还原

【Abstract】 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.更多还原