燃烧法合成YVO4：Ln（Ln=Eu，Sm）荧光粉及其发光特性

采用柠檬酸和尿素作为燃料,通过燃烧法分别制备了Eu^3＋和Sm^3＋单掺的YVO4荧光粉。采用差示扫描量热仪对样品前驱体的热分解特性进行分析,并采用X射线衍射仪、扫描电子显微镜和荧光分光光度计对所得样品的物相、表面形貌、激发光谱和发射光谱进行表征。实验结果表明,所得样品的晶相为YVO4,四方晶系。并讨论了该荧光粉发光性能的影响因素。     

低温熔盐合成YVO4:Eu3+红色荧光粉及其发光性能研究

采用低温熔盐法合成了YVO4:Eu3+红色发光材料,用X射线粉末衍射对其结构进行表征,证实样品为具有锆石结构的YVO4相;扫描电镜结果表明,低温熔盐法合成的样品粒径明显小于高温固相法,而且显著降低了烧结温度;荧光光谱分析表明:YVO4:Eu3+的激发光谱在250～350nm范围内有极强宽带吸收,对应于Y3+-O2-、E...     

YVO_4:Eu纳米微粒的合成及光谱性质研究

在水热条件下,以Y(NO3)3.6H2O,Eu2O3,NH4VO3,Na3C6H5O7.2H2O为原料合成了YVO4纳米微粒以及稀土离子Eu3+掺杂的YVO4:Eu纳米微粒,利用XRD,FE-SEM,TEM,HRTEM和SAED对所得产物的结构和形貌进行表征,并用FT-IR、F-4600对所得产物的光谱性质进行了分析.结果表明,产物为纯净的四方相YVO4,具有较为规则的饼状形貌,单个饼状YVO4纳米微粒的直径约为500nm.XRD图谱显示稀土离子Eu3+取代了Y3+进入YVO4晶体,但在纳米YVO4:Eu的荧光光谱上没有出现VO43-发射峰,这表明YVO4是良好的发光基质材料.水热合成方法简单易行,合成出的YVO4:Eu粒子荧光强度大且荧光强度稳定.     

水热法制备NaY(WO4)2∶Eu3+荧光粉及其上转换发光性能研究

采用水热法合成出NaY(WO4)2∶Eu3+荧光粉.研究了水热反应时间对样品晶体结构、形貌及上转换发光性能的影响.结果 表明:水热反应6h后所得样品均属四方相,且掺入的Eu3+进入到基质NaY(WO4)2晶格中,并占据Y3+的格位.添加聚乙二醇(PEG-2000)作为表面活性剂,可得到形貌统一且分散性良好的微米针状球....     

Eu2+、Dy3+、Li+共掺杂CaSi2O2N2荧光粉的发光性能

采用高温固相反应法制备了一系列白光LED用CaSi2O2N2:0.05Eu2+,xDy3+,xLi+(0≤x≤0.03)荧光粉.利用X射线衍射仪对样品的物相结构进行了分析,结果表明:Dy3+和Li+离子的掺入没有改变CaSi2O2N2:Eu2+荧光粉的主晶相.利用荧光光谱仪对样品的发光性能进行了测试,发现所有样品的激发光谱均覆盖了从近紫外到蓝光的较宽范围,400 nm激发下得到的发射光谱为宽波段的单峰,峰值位于545 nm左右,是Eu2+离子5d-4f电子跃迁引起的.Dy3+离子掺杂可以提高CaSi2O2N2:Eu2+荧光粉的发光强度,Dy3+与Li+共掺杂可进一步提高荧光粉的发光强度,当Dy3+和Li+的掺杂量为1mol%时,荧光粉的发光强度达到最大值,是单掺杂Eu2+的荧光粉发光强度的157%.     

Bi3+、Y3+掺杂对Gd2(MoO4)3:Eu3+发光性能的影响

采用高温固相法制备Bi3+、Y3+掺杂LED用小颗粒红色荧光粉Gd2(MoO4)3∶Eu3+.通过X粉晶衍射仪、F-4500荧光分光光度计、JSM-35CF型扫描电子显微镜对离子掺杂后的红色荧光粉进行检测和表征.结果表明,经过Bi3+、Y3+掺杂,红色荧光粉Gd2(MoO4)3∶Eu3+的相对发光强度提高,荧光粉晶体的结构完整、颗粒细小均匀,平均粒径约为2靘,具有较好的涂覆性能,能满足白光LED用红色荧光粉的要求.     

喷雾热解法制备球形SrMoO4∶Eu3+荧光粉及发光性能

采用喷雾热解法制备了球形SrMoO4∶Eu3+荧光粉。研究了温度对SrMoO4∶Eu3+荧光粉体的晶相结构、显微形貌及发光性能的影响。结果表明,不同温度下得到的粉体都具有纯的SrMoO4晶相;300℃下喷雾制得的钼酸锶粉体颗粒部分具有空心球形结构,在400、500和600℃下喷雾制得的钼酸锶粉体颗粒呈现实心球形结构;温度为500℃时所得样品发光强度最强。     

Lu2(MoO4)3:Eu3+荧光粉的制备及热增强发光

采用固相法制备了Lu₂(MoO₄)₃:Eu³⁺系列红色荧光粉，利用X射线粉末衍射仪(XRD)、场发射扫描电子显微镜(FE-SEM)、能谱仪(EDS)和荧光光谱(PL)仪对制备荧光粉的结构、形貌、元素组成及光致发光性能进行表征与分析。实验结果表明Eu³⁺成功掺入基质晶格中并得到Lu₂(MoO₄)₃:Eu³⁺纯相样品，荧光粉颗粒大小在2μm左右。制备温度依赖样品光致发光结果表明1 000℃下制备Lu₂(MoO₄)₃:Eu³⁺样品发光性能最好。煅烧时间依赖样品光致发光结果表明1 000℃下煅烧时间为6 h时样品发光效果最好。反常于荧光粉发光热猝灭现象，Lu₂(MoO₄)₃:Eu³⁺样品在外界测试温度为250℃左右时出现热增强...     

Li+掺杂对NaY(WO4)2:0.07Yb3+/0.025Er3+上转换荧光粉发光性能的影响

采用高温固相法制备一系列不同浓度Li+离子(0.00,0.03,0.05,0.07,0.09和0.11 mol)掺杂NaY(WO4)2:0.07Yb3+/0.025Er3+上转换荧光粉.通过X射线衍射(XRD)、扫描电子显微镜(SEM)、荧光发射光谱及荧光衰减曲线等表征所制备样品物相、形貌及发光性能.结果表明,晶体结晶...     

白光LED用LiY(MoO_4)_2∶RE~(3+)(RE=Eu,Sm,Pr)荧光粉的制备与性能

采用水热法制备了LiY(MoO4)2∶RE3+(RE=Eu、Sm、Pr)系列荧光粉,通过X射线衍射(XRD),扫描电镜(SEM)对该系列荧光粉的物相、形貌进行了表征。结果表明,稀土离子的掺入没有改变荧光粉的晶相,3种稀土离子的加入使得LiY(MoO4)2粉体形成片层状结构。利用PL(光致发光光谱)对样品的发光性能进行了测试,分析了稀土离子掺杂浓度对发光强度的影响并进行浓度猝灭机理分析,结果表明,Eu3+、Sm3+、Pr3+最佳掺杂浓度分别为7%,4%和1.5%。LiY(MoO4)2∶Eu3+荧光粉能够很好地被395nm的紫外光和465nm的蓝光有效激发而发射红光,而Sm3+和Pr3+掺杂的LiY(MoO4)2分别在406和453nm激发下,发射出650和657nm的红光,LiY(MoO4)2∶RE3+(RE=Eu、Sm、Pr)系列荧光粉有望成为白光LED用红色荧光粉。     

Study on UV excitation properties of Y2O3:Ln3+ (Ln = Eu3+ or Tb3+) luminescent nanomaterials

Y2O3:Ln3+ (Ln = Eu or Tb) nanocrystals with different Ln3+ doping concentrations and average sizes were prepared by chemical self-combustion. The corresponding bulk materials with various doping concentrations were obtained by annealing the nanomaterials at high temperature. The emission spectra, excitation spectra, and X-ray diffraction spectra were used in this study. It was found that the charge transfer band of Y2O3:Eu3+ red-shifted as particle size decreased, and the charge transfer band in the 5-nm particles obviously broadened toward the long wavelength. It was also found that the profile of excitation spectra corresponding to the 4f5d (4f8 --> 4f(7)5d1) transition changed a lot with the variation of the particle size. The dependence of the excitation spectra of Y2O3:Ln3+ on particle size was investigated.     

Template-free Fabrication and Luminescent Characterization of Highly Uniform and Monodisperse Y2O2S:Sm3+ Hollow Submicrospheres

Well dispersed and homogeneous Y2O2S:Sm3+ hollow submicrospheres were successfully achieved by a templatefree solvothermal method combining with a postcalcining process.The crystalstructure and particle morphology were investigated by the X-ray diffraction(XRD),Fourier transform infrared(FT-IR) spectra,scanning and transmission electron microscopy(SEM and TEM),respectively.A possible growth mechanism was proposed to reveal the formation process.Luminescence properties of the Y2O2S:Sm3+ long-lasting phosphor were analyzed by measuring the excitation spectra,emission spectra,afterglow decay curve and thermoluminescence curve.The excitation spectra indicated that the phosphor could be excited effectively by the ultraviolet-light emitting diode(UV-LED) or blue LED,and the emission spectra showed that the phosphor could emit red light from 600 to 650 nm.     

Solvothermal synthesis of SrMoO4:Ln (Ln = Eu, Tb, Dy) nanoparticles and its photoluminescence properties at room temperature

Rare-earth ions (Eu³⁺, Tb³⁺, Dy³⁺) doped SrMoO₄ nanoparticles were prepared by solvothermal route using oleic acid as surfactant to control the particle shape and size. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), photoluminescence spectra (PL) and the kinetic decay times were applied to characterize the obtained samples. The XRD patterns reveal that all the doped samples are assigned to the scheelite-type tetragonal structure of SrMoO₄ phase. In addition, the as-synthesized SrMoO₄:Ln (Ln = Eu³⁺, Tb³⁺, Dy³⁺) particles are high purity well crystallized and with the average size of 30-50 nm. The possible formation process of SrMoO₄:Ln (Ln = Eu³⁺, Tb³⁺, Dy³⁺) nanoparticles have been discussed as well. Upon excitation by ultraviolet radiation, the as-synthesized SrMoO₄:Ln (Ln = Eu³⁺, Tb³⁺, Dy³⁺) nanoparticles exhibit the characteristic emission lines of corresponding Eu³⁺, Tb³⁺, Dy³⁺, respectively.     

Nanostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Tb3+ particles: polyol-mediated synthesis and luminescent properties

Nano-submicrostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Tb3+ particles were prepared by polyol method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), thermogravimetry-differential thermal analysis (TG-DTA), photoluminescence (PL), cathodo-luminescence (CL) spectra and PL lifetimes. The results of XRD indicate that the as-prepared samples are well crystallized with the scheelite structure of CaWO4. The FE-SEM images illustrate that CaWO4 and CaWO4 : Pb2+ and CaWO4 : Tb3+ powders are composed of spherical particles with sizes around 260, 290, and 190 nm respectively, which are the aggregates of smaller nanoparticles around 10-20 nm. Under the UV light or electron beam excitation, the CaWO4 powders exhibits a blue emission band with a maximum at about 440 nm. When the CaWO4 particles are doped with Pb2+, the intensity of luminescence is enhanced to some extent and the luminescence band maximum is red shifted to 460 nm. Tb(3+)-doped CaWO4 particles show the characteristic emission of Tb3+ 5D4-7FJ (J = 6 - 3) transitions due to an energy transfer from WO4(2-) groups to Tb3+.     

Molten salt synthesis and luminescent properties of YVO4:Ln (Ln = Eu3+, Dy3+) nanophosphors

Eu3+ and Dy(3+)-doped YVO4 nanocrystallites were successfully prepared at 400 degrees C in equal moles of NaNO3 and KNO3 molten salts. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, transmission electronic microscopy (TEM), photoluminescence (PL) spectrum and lifetime were used to characterize the nanocrystallites. XRD results demonstrate that NaOH concentration and annealing temperature play important roles in phase purity and crystallinity of the nanocrystallites, the optimum NaOH concentration and annealing temperature being 6:40 and 400 degrees C respectively. TEM micrographs show the nanocrystallites are well crystallized with a cubic morphology in an average grain size of about 18 nm. Upon excitation of the vanadate group at 314 nm, YVO4:Eu3+ and YVO4:Dy3+ nanocrystallites exhibit the characteristic emission of Eu3+ and Dy3+, which indicates that there is an energy transfer from the vanadate group to the rare earth ions. Moreover, the structure and luminescent properties of the nanocrystallites were compared with their bulk counterparts with same composition in detail.     

白光LED用YAG∶Ce~(3+)发光材料的性能增强研究

以硼酸和碱土氟化物作为助熔剂,调整助熔剂比例和组分,采用高温固相法合成一系列白光LED用YAG∶Ce3+发光材料。采用XRD、扫描电镜(SEM)和荧光光谱(PL)等对样品进行表征。研究表明,合适的助熔剂有助于降低样品的烧结温度,不会有杂相产生,加入不同浓度和成分的助熔剂对样品的发射、激发光谱形状和峰值波长位置无影响,但对发光强度影响较大;采用助熔剂质量分数为0.4%(0.2%H3BO3-0.2%BaF2)时,所合成样品的颗粒比较均匀,发光性能的增强最为有效。将其和蓝光Ga(In)N芯片封装成白光LED,光效也得到显著提高。封装后白光LED的色坐标为(0.3341,0.4190),色温为5470K,显色指数为67,光效可达到78.3lm/W,高于其它条件合成荧光粉封装的白光LED。     

Eu3+掺杂β-NaYF4∶20%Yb3+, 0.5%Tm3+的合成与双频光转换性能

采用高温溶剂热法合成了Eu3+掺杂的双频转换发光材料β-NaYF4∶20%Yb3+,0.5%Tm3+,并使用X射线衍射仪(XRD)、场发射扫描电镜(FESEM)和光致发光谱(PL)仪对所制备样品的物相结构、形貌特征和发光性质进行了表征,通过分析发光原理,解释了上、下转换发光的竞争机制,并探讨了稀土离子Tm3+与Eu3+之间的能量转移。结果表明:所合成的β-NaYF4∶20%Yb3+,0.5%Tm3+,xEu3+为纯六方相晶体,结晶良好,颗粒尺寸在200nm左右。改变Eu3+的掺杂浓度后晶格结构没有发生明显变化,样品可在394nm和980nm光的激发下,分别发生下转换和上转换发光。     

Molten salt synthesis and luminescent properties of YVO4:Ln (Ln = Eu3+, Dy3+) nanophosphors

Eu3+ and Dy(3+)-doped YVO4 nanocrystallites were successfully prepared at 400 degrees C in equal moles of NaNO3 and KNO3 molten salts. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, transmission electronic microscopy (TEM), photoluminescence (PL) spectrum and lifetime were used to characterize the nanocrystallites. XRD results demonstrate that NaOH concentration and annealing temperature play important roles in phase purity and crystallinity of the nanocrystallites, the optimum NaOH concentration and annealing temperature being 6:40 and 400 degrees C respectively. TEM micrographs show the nanocrystallites are well crystallized with a cubic morphology in an average grain size of about 18 nm. Upon excitation of the vanadate group at 314 nm, YVO4:Eu3+ and YVO4:Dy3+ nanocrystallites exhibit the characteristic emission of Eu3+ and Dy3+, which indicates that there is an energy transfer from the vanadate group to the rare earth ions. Moreover, the structure and luminescent properties of the nanocrystallites were compared with their bulk counterparts with same composition in detail.     

立方相NaYF_4∶Ce~(3+)材料的合成及上转换发光性能

以氟化钠、硝酸钇、硝酸铈为原料,采用水热法和共沉淀法合成棒状NaYF4∶Ce3+材料,利用XRD、SEM、红外光谱、荧光光谱分析仪对其结构和发光性能进行表征。结果表明,制备样品均为立方相结构,表面含有以化学吸附方式存在的EDTA分子。经水热法制备样品的上转换发射发射出波长在404.5nm和436nm处的蓝光,以及波长在520.5nm和539nm处的绿光。     

NaYF4:Er3+六棱柱的水热合成及上转换发光性能

以氟化钠、硝酸钇、硝酸铒为原料,利用水热法合成NaYF4:Er3+材料。利用X射线粉末衍射仪(XRD)、场扫描电子显微镜(SEM)、红外吸收(FT-IR)以及发光光谱等手段对产物的物相结构、形貌和荧光性能进行分析。结果表明,NaYF4:Er3+为六角棱柱晶体,属于六方晶系,具有P63/m(176)空间点群结构。在980nm光激发下,NaYF4:Er3+展现出强的上转换光,波长在520nm和539nm为绿光发射,对应为Er3+离子的2 H11/2→4/I15/2和4S3/2→4/I15/2跃迁发射,而652nm为红光发射,则对应于Er3+离子的4F9/2→4/I15/2跃迁发射。