高亮度白光LED用YAG:Ce3+荧光粉的研制

根据蓝光芯片的发光特性,从激活剂、助熔剂、基质Y3+的替代物等方面较系统地研究了YAG:Ce3+荧光粉的制备.最终的荧光粉产品制成φ5mm封装20mA蓝光激发的白光LED后,光效可达70lm/W,显色指数≥80.     

高亮度白光LED用YAG∶Ce~(3+)荧光粉的研制

根据蓝光芯片的发光特性,从激活剂、助熔剂、基质Y3+的替代物等方面较系统地研究了YAG∶Ce3+荧光粉的制备。最终的荧光粉产品制成5mm封装20mA蓝光激发的白光LED后,光效可达70 lm/W,显色指数≥80。     

白光LED用氮化物荧光粉的研究现状及发展趋势

对白光LED(发光二极管)用氮化物荧光粉目前的研究状况、存在问题及发展趋势进行了分析和论述。重点介绍了M2Si5N8∶Eu(M=Ca,Sr,Ba)氮化物荧光粉,展望了新型氮化物荧光粉的应用前景,并指出开发新型氮化物荧光粉的关键在于高纯金属Eu、Ca、Sr等原料的制备及氮化物粉的合成这两个方面。     

Kinetics of Fluorescence Decay in Er^3＋ ：YAG under 408.6 nm Excitation

The violet and green fluorescence spectra and the kinetics of fluorescence decay in Er^3＋ ：YAG crystal under 408.6 nm excitation were investigated by the time-resolved laser-induced fluorescence technique. The influence of multiphonon and energy transfer on the fluorescence decay of the ^4S3/2 rnultiplet were theoretically analyzed. A good agreement of the measured and the simulated decay curves was achieved. The continuous profile variety of the decay curves in the region from 548 to 561.2 nrn is found and it originates from the fluorescence overlap of ^2G9/2 and ^4S3/2 and the intensity ratio dominates the profile.     

用于白光LED的荧光粉Sr3MgSi2O8:Eu2+的发光特性

使用高温固相法制备不同NH4Cl(作为助熔剂)加入量和不同Eu2+浓度的Sr3MgSi2O8:Eu2+,并研究其成相和发光性质.研究结果表明:NH4Cl加入量为24%时,样品为纯相,发光最强.Sr3MgSi2O8:Eu2+样品在近紫外区存在强激发带(250～400 nm),谱峰位于366 nm相应的发射谱带位于蓝光区(420～500nm),为一个不对称宽带,谱峰位于457 nm,该发射带由两个发射峰组成,其位置较接近,因此不能复合出白光,Sr3MgSi2O8:Eu2+仅适合作为紫外LED芯片激发的蓝光荧光粉.     

共沉淀法制备白光LED用CaMO_4:Eu~(3+),Bi~(3+)(M=Mo,W)红色荧光粉及其发光性能的研究

采用共沉淀法制备了Ca_(0.93-x)(Mo_(0.9)W_(0.1))O_4∶Eu_(0.07)~(3+),Bi_x~(3+)(0≤x≤0.05)系列样品,通过XRD、SEM及荧光光谱仪对粉体的晶体结构、形貌及荧光性能进行测试和表征。结果表明,Bi~(3+)、Eu~(3+)及WO_4~(2-)的掺杂没有改变CaMoO_4原有的四方晶系体心结构,且样品粒径分布较均匀,无明显团聚现象。随着Bi~(3+)的掺杂,Ca_(0.93-x)(Mo_(0.9)W_(0.1))O_4∶Eu_(0.07)~(3+),Bi_x~(3+)样品的激发光谱带边会发生红移,且激发强度呈现先增强后减弱的趋势,其发射光谱也具有相应的规律,Bi~(3+)的最佳掺杂浓度为x=0.02 mol,在395 nm激发下,样品的发光强度提升至134%;较之商用红色荧光粉Y_2O_2S∶Eu~(3+),Ca_(0.91)(Mo_(0.9)W_(0.1))O_4∶Eu_(0.07)~(3+),Bi_(0.02)~(3+)样品显现出更好的色纯度和发光强度,适合于近紫外LED用红色荧光粉。     

白光LED用高效荧光转化材料钪硅酸盐的研究进展

由于目前LED用绿色荧光粉体系分别存在热稳定性差、显色指数低、制备复杂苛刻等问题,因此日本三菱化学开发出了一种新型LED用绿色Ca3Sc2Si3O12∶Ce3+钪硅酸盐荧光粉。在综述Ca3Sc2Si3O12∶Ce3+荧光性能的基础上,总结分析了Ca3Sc2Si3O12∶Ce3+荧光发光材料的晶体结构和发光机制,表明这种荧光粉兼备了硅酸盐和YAG∶Ce荧光粉的石榴石结构,使得晶体场能够与Ce3+配合展现出良好的匹配性,可以很好的与现行蓝光芯片匹配得到高品质的白光,并且类似YAG晶体的石榴石结构有着良好的发光性能和热稳定性;讨论了在电荷补偿作用和这种作用下基质改变后荧光粉的性能变化,以及激活剂改变、能量传递的影响,表明荧光粉光色可调幅度较大,能够根据不同变化产生不同的发光;然后分固相法和液相法总结了该荧光粉的制备方法,证明该荧光粉烧结温度低、合成工艺适应性广泛,并且高温固相法是工业化生产该系列荧光粉的最佳方法;最后展望了Ca3Sc2Si3O12∶Ce3+荧光转换材料的发展趋势和在白光LED中的应用前景,作为一种新型高效的白光LED用绿色荧光粉,需要进一步的研究和探索。     

YAG:Ce3+荧光粉制备技术的研究进展

综述了白光LED用YAG:Ce3+黄色荧光粉多种制备技术的新进展,包括固相反应法、溶胶-凝胶法、喷雾干干燥法、燃烧法、共沉淀法、共沉淀-熔盐法等,并对这些方法的优缺点进行了综合比较,展望了该领域的发展前景及研究趋势.     

熔盐法制备白光LED用Ca_(1-x)Eu_xWO_4红色荧光粉的工艺研究

采用熔盐法合成了白光LED用Ca_(1-x)Eu_xWO_4红色发光材料。利用XRD、SEM、激光粒度仪、荧光光谱仪等手段对荧光粉物相、颗粒形貌、粒径及发光性能进行了表征。考察了Eu~(3+)掺杂浓度、熔盐的种类、熔盐用量以及焙烧温度和时间等工艺参数对白光LED用Ca_(1-x)Eu_xWO_4荧光粉性能的影响。结果表明:在CaWO_4中掺杂Eu~(3+)没有改变基质的四方晶系白钨矿结构;随着Eu~(3+)掺杂量的增加,Eu~(3+)的特征发射峰强度逐渐增强,Eu~(3+)掺杂浓度达到30%也不会发生浓度猝灭现象;以复合熔盐(NaCl-KCl)为助熔剂体系,熔盐与荧光粉的摩尔比为3,在850℃下焙烧3 h,可获得分散性好、表面光滑平整、颗粒细小,形貌为四方双锥结构的白光LED用Ca_(1-x)Eu_xWO_4红色荧光粉。     

Preparation and Upconversion Luminescence of Y3Al5O12 ： Yb^3＋ , Er^3＋ Trapsparent Ceramics

YAG： 1% （atom fraction） Yb^3＋ , 0.5% （atom fraction） Er3＋ transparent ceramics were fabricated by the solid state reaction method using high-purity Y2O3, Al2O3, Yb2O3, and Er2O3 powders as starting materials. The mixed powder compact was sintered at 1760 ℃ for 6 h in vacuum and annealed at 1500 ℃ for 10 h in an air atmosphere. The ceramics consisted of about 10μm grains and exhibited a pore-free structure. The optical transmittance of the ceramics at 1064 nm was nearly 80%. Upconversion emissions were investigated on the ceramics pumped by a 980 nm continuous wave diode laser, and strong green emission centered at 523 and 559 nm and red emission centered at 669 nm were observed, which originated from the radiative transitions of ^2H11/2→^4I15/2, ^4S3/2→^4I15/2, and ^4F9/2→^4I15/2 of Er^3＋ ions, respectively.     

红色荧光粉La2O3：Eu3＋的合成及发光性质

利用复合沉淀法制备了性能稳定的红色荧光粉La2O3：Eu3＋,同时研究了煅烧温度及掺杂Eu3＋浓度对La2O3：Eu。’发光性能的影响．通过X射线粉末衍射（XRD）和扫描电子显微镜（SEM）来表征荧光粉的晶体结构和颗粒大小及形貌：用激发光谱和发射光谱以及荧光衰减曲线来袁征荧光粉的荧光性能．结果表明：煅烧温度在900℃时,所制备样品为六方晶系La2O3：Eun;SEM图显示掺杂Eu0＋含量为5％的La2O3颗粒直径为15μm左右．最大发射波长和激发波长分别为626nm和396nm,发射光谱中596nm和626nm的发射峰对应的是Eu3＋离子的0D—F1和5D—F2跃迁,其荧光寿命为0．754ms．     

VUV Spectroscopy of GdPO4： Eu^3＋ and GdBO3： Eu^3＋

The emission and the excitation spectra of GdPO4 ： Eu^3＋ and GdBO3： Eu^3 ＋ prepared by solid state reaction method were investigated using the synchrotron radiation source of SUPERLUMI station of HASYLAB. The energy transfer between Gd^3＋ and Eu^3＋ was discussed with the probability of quantum cutting process. In the excitation spectra monitoring the red emission from Eu^3＋ , the distinct lines corresponding to the intraconfigurational 4f-4f transitions from Gd^3＋ were observed for both samples, indicating an efficient energy transfer from host Gd^3＋ ions to the doped Eu^3＋ ions. The efficient energy transfer is necessary for the quantum cutting process based on the two-step energy transfer from Gd^3＋ to Eu^3＋ . However, the overlapping of the lines corresponding to Gd^3＋ ：^8S7/2→^6GJ and the broad excitation band （180 - 270 nm） due to Eu^3＋- O^2- charge transfer states （CTS） around 200 nm cause excitation energy on ^6GJ levels to dissipate into CTS by direct energy transfer, unfavorable to the cross relaxation energy transfer between Gd^3＋ and Eu^3＋, thus unfavorable to the quantum cutting process. With the help of the general rules governing the energy positions of Eu^3＋-O^2- ：CTS, the suggestions concerning searching suitable oxide hosts for Gd^3＋-Eu^3＋ quantum cutting were made.     

白光LED用LaPO4:Eu3+红色荧光粉的合成与表征

利用水热法制备了性能稳定的红色荧光粉LaPO4:Eu3+,同时研究了不同的Eu3+浓度、煅烧温度对荧光粉发光性能的影响.通过X射线粉末衍射(XRD)和扫描电子显微镜(SEM)来表征荧光粉的晶体结构和颗粒大小及形貌;用激发光谱和发射光谱以及荧光衰减曲线来表征荧光粉的荧光性能.结果表明:未煅烧时前躯体主要是六方晶相LaPO4·0.5H2O,煅烧温度在900℃时,所制备样品为单斜相LaPO4:Eu3+;SEM图像显示5 at.%Eu3+掺杂LaPO4呈椭球形,颗粒长约为500 nm,宽约为300 nm.最大发射波长和激发波长分别为592 nm和393 nm,发射光谱中592 nm和612 nm的发射峰对应的是Eu3+离子的5D0→7F1和5D0→7F2跃迁.其荧光寿命为3.32 ms.     

Effect of fluxes on structure and luminescence properties of Y3Al5O12：Ce^3＋ phosphors

Ce3+-activated yttrium aluminum garnet (YAG) was prepared by the solid-state reaction, in which H3BO3, LiF, NaF, KF and BaF2 were used as the fluxes. The effect of fluxes on optical properties of phosphors was studied in detail, especially the fluxes of alkali fluorides, which could enhance the emission intensity and change the wavelength of emission peaks. Among these YAG:Ce phosphors, the phosphor sintered with H3BO3 and NaF exhibited the strongest emission. The emission peaks of phosphors prepared with fluxes from LiF to KF were shifted to long wavelength. The effect of NaF concentration on the emission intensity of YAG:Ce was also investigated. The value of emis-sion intensity reached the maximum when the concentration of NaF was 0.5%.     

Synthesis and Luminescence Properties of Gd2O3：Eu^3＋ Phosphors

Gd2O3: Eu^3 phosphors were prepared by urea homogeneous precipitation with different surfactant and sol-gel method. XRD patterns show that all the obtained samples are in cubic Gd2O3, and the results of FTIR and fluorescent spectra conformed that OP is a good surfactant for preparing the Gd2O3:Eu^3 phosphors. The SEM photographs show that the particles prepared by urea homogeneous precipitation method are all spherical and well-dispersed, and grain morphology can be controlled by different surfactant. XRD and SEM indicate that the particle sizes prepared by sol-gel method are in the range of 5-30 nm, and the grain sizes increase with increasing of heated temperatures. Luminescence spectra indicat that the main emission peaks of all samples are at 610 nm, the intensities are different from samples prepared with different surfactant and the luminescence intensities increase with increasing of annealed temperatures.     

Luminescent properties of Ba3Gd（BO3）3：Eu^3＋ phosphor for white LED applications

Luminescent material Ba3Gd(BO3)3 doped with Eu3+ ion was prepared by high temperature solid-state method. The preparing conditions, luminescent properties, and particle morphology of Ba3Gd(BO3)3:Eu3 + phosphor were studied with X-ray diffraction (XRD), fluorescence spectroscopy, and scanning electron microscopy (SEM). The results obtained by XRD showed that pure phase of Ba3Gd(BO3)3 was obtained at 1000℃. Images from SEM displayed that the particles of Ba3Gd(BO3)3:Eu3+ phosphor had a spherical shape with an average diameter of about 200-400 nm. The luminescence spectra showed that Ba3Gd(BO3)3:Eu3+ phosphor was effectively excited by the near ultraviolet (UV) light (396 nm) and blue light (466 nm). The main emission peaks of Ba3Gd(BO3)3:Eu3+ phosphor were assigned to the supersensitive transition 5D0-7F2 (611 and 616 nm) of Eu3+ ion when samples were excited at 255 and 396 nm, respectively, and the luminescent intensity of Ba3Gd(BO3)3:Eu3+ at 611 and 616 nm reached to the maximum when the doped content of Eu3+ ion was 10mol.%. Therefore, this phosphor could be a promising red component for possible applications in the field of white LED.     

作为白光LED用铕掺杂氟化镧红色荧光粉的制备与光谱性能研究

采用水热法制备具有单一相六方晶系的LaF₃:Eu3+纳米荧光粉.通过X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、光致发光光谱(PL)和荧光衰减曲线对LaF₃:Eu3+纳米荧光粉进行表征.LaF₃:Eu3+荧光粉的激发光谱主要由250 nm处的宽带(O2-→Eu3+的电荷转移跃迁)和一些尖峰(Eu3+ f-f跃迁)构成,其中位于近紫外区396 nm处有一较强的激发峰.通过发射光谱探测Eu3+在LaF₃晶体中的局部晶场环境.在298 K下激发光谱和发射光谱可知,在六方晶系的LaF₃纳米晶体中的Eu3+晶格位置从D_4h降至到C_2v,这是由于晶格变化所造成的.在396 nm激发下,观测到较优掺杂浓度为10%的LaF₃:Eu3+荧光粉在591 nm(5D₀→7F₁跃迁)处有强烈的红色发射峰.其发光性能表明,LaF₃:Eu3+红色荧光粉在近紫外发光二极管领域具有潜在的应用价值.      

国内PDP用绿色荧光粉的研究进展

简要介绍了目前国内等离子体显示器（PDP）用绿色荧光粉的研究现状及合成研究进展，并展望了其发展前景。     

Comparative Study on Photoluminescent Properties of CaGdAlO4：Eu3＋ Phosphors Synthesized with Three Methods

CaGdAlO4 ： Eu^3＋ powder phosphors were prepared using citrate sol-gel （CSG）, haft-dry and half-wet （HDW） and solid state （SS） methods, respectively. X-ray diffraction results confirm the formation of CaGdAlO4：Eu^3＋ at 900 % （CSG）, 1200℃ （HDW） and 1400℃ （SS）, respectively. Field emission scan electron microscopy （FE-SEM） images show that the CaGdAlO4：Eu^3＋ powder prepared by the CSG and HDW method has an elliptical shape and that prepared under the SS method has a flaky shape. Upon excitation with 280 nm UV light, all the CaGdAlO4： Eu^3＋ powders show bright red emission on account of the 4f-4f transitions of the Eu^3＋ ions. Moreover, the size of the phosphor particles and the emission intensity increase with the increase of calcined temperature. At the same calcination temperature of 1400 ℃, the ^5D0→^7F2 emission intensity of the sample prepared by HDW method is the highest. Stark components of the ^5D0→^7FJ emission transitions, both at room temperature and at a low temperature, reveal that the Eu^3＋ ions occupy only one site with non-centrosymmetry in the crystals.