氢氧化镧湿法氟化法合成氟化镧工艺研究

采用了氢氟酸直接氟化氢氧化镧浆液的制备工艺，考察了工艺的可行性。研究了氢氟酸浓度、用量、反应温度、反应时间等因素对产物含氧量、氟化率和制备过程中过滤、洗涤的影响。通过差热分析、扫描电镜、X射线衍射等手段对产品的组成、形貌、结构等进行了研究。制备工艺为固液反应，工艺简单，产品分散性好，易过滤洗涤，质量稳定，工业可操作性强，流程短。     

蓝光激发锡酸盐红色荧光粉的光谱性能

采用高温固相法合成了Sr2-xSnO4∶Eu3+x系列红色发光粉,该荧光粉属于四方晶系结构。以465 nm的蓝光激发样品,Sr2-xSnO4∶Eu3+x荧光粉发射红光,以Eu3+的5D0-7F2电偶极跃迁发光最强。该材料能非常好地吸收465 nm波长的光。研究了激活剂Eu3+的浓度对Sr2-xSnO4∶Eu3+x样品发光性能的影响。结果表明,Eu3+的最佳掺杂浓度为5%。     

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。     

多面体镧铈铽氧化物荧光粉的制备研究

采用共沉淀-焙烧法制备镧铈铽氧化物绿色荧光粉,研究了表面助剂、酸碱度、底液溶剂及反应温度对镧铈铽氧化物形貌的影响.用X衍射、扫描电镜以及光学显微镜对产物进行分析表征.结果表明,前驱体镧铈铽草酸盐的结晶环境对镧铈铽氧化物的形貌有着重要影响;在非离子表面助剂、强酸性和有机溶剂做底液的体系环境中更利于得到分散性好、形貌规则、球形度较高的多面体镧铈铽氧化物.     

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。     

白光LED用YAG：Ce^3＋荧光粉的研究进展

介绍了近年来自光YAG：Ce^3＋荧光粉发光特性和合成方法,并展望该领域的发展前景及今后的研究趋势。     

稀土氟化镧对多孔铝的性能影响研究北大核心

采用添加造孔剂的方法制备多孔铝试样。研究烧结温度和稀土氟化镧含量对多孔铝材料的性能影响。结果表明,烧结温度为600℃时多孔铝材料的烧结性能最佳;稀土氟化镧的适量加入可以提高多孔铝的力学性能;稀土氟化镧添加量为0.5%时,多孔铝材料的抗压强度和弹性模量最佳,分别为52.4 MPa和1.56 GPa。     

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.     

SiO2@ZnWO4∶Eu3+红色荧光粉的制备及其发光性质研究

以正硅酸乙酯为硅源,用水热法制备了SiO2@ZnWO4∶Eu3+荧光粉,对样品分别进行了X射线衍射(XRD)、透射电镜(TEM)、荧光光谱(PL)等表征。XRD结果表明,当水热反应温度为180℃,反应时间12小时,可以得到ZnWO4的纯相。TEM和EDS结果表明,样品中含有Si、Eu、O、Zn、W元素。荧光光谱结果表明,SiO2@Zn-WO4∶Eu3+荧光粉能够被393 nm的紫外光激发,在615 nm处发出红色荧光,且SiO2@ZnWO4∶Eu3+荧光粉的发射光谱中电偶极跃迁5D0→7F2强度大于磁偶极跃迁5D0→7F1的强度,表明Eu3+在其中处于没有对称中心的格位。     

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.     

Synthesis and photoluminescence properties of ZnTiO3:Eu3+ red phosphors via sol-gel method

ZnTiO3:Eu3+ phosphors were synthesized with different concentrations of Eu3+ doping through sol-gel method. The samples were calcined at different temperatures for 2 h in air. The synthesized powders were characterized by X-ray diffraction(XRD), scanning electron microscopy-energy dispersive spectroscopy(SEM-EDS), transmission electron microscopy(TEM), Raman and photoluminescence spectroscopy. The XRD results showed that the Zn Ti O3:Eu3+ phosphors doped with different concentrations of Eu3+ ions calcined at 600 oC were of single phase, which indicated that the Eu3+ ions had been successfully incorporated into the Zn Ti O3 host lattice and did not destroy the lattice structure of Zn Ti O3 host. The Raman spectrum, SEM and TEM also proved that the doping of Eu3+ did not change the lattice structure of hexagonal Zn Ti O3 host. The photoluminescence(PL) of Eu3+ ions with the main emission peak at 614 nm was observed to increase with Eu3+ concentrations from 0.5 mol.% to 2.0 mol.% and decreased when the concentration was increased to 2.5 mol.%. The decrease in the PL intensity at higher Eu3+ concentrations could be associated with concentration quenching effect. The CIE1931 chromaticity diagram(x, y) of Zn Ti O3:2.0 wt.%Eu3+ phosphors were located in the red region(x=0.652, y=0.347). The luminescence properties suggested that Zn Ti O3:Eu3+ phosphors might be regarded as a potential red phosphor candidate for light emitting diodes(LEDs).     

Y2O3-SiO2∶Eu3+,Bi3+荧光材料的结构及性能研究

用溶胶-凝胶法(Sol-gel法)低温合成了Y2O3-SiO2∶Eu3+,Bi3+红色发光粉.X射线实验研究发现,850℃时,样品晶体结构为Y2SiO5,属单斜晶系(a=9.012,b=0.979,c=6.630),空间点群为PI1/C;SEM实验显示发光体为不规则片层结构;粒度分析表明发光体粒度分布均匀,平均粒度为0.79μm;T≥600℃时,发光体出现温度猝灭现象.     

Influence of urea on microstructure and optical properties of YPO4：Eu^3＋ phosphors

YPO4:Eu 3+ phosphors were synthesized by solution coprecipitation method assisted by urea in the precursor reaction solution. X-ray diffraction spectral analysis showed that the samples synthesized with urea had smaller particle size and lower crystallinity than those samples synthesized without urea.Moreover,the calculated strain result indicated that the Eu 3+ site in the former exhibited a lower crystal field symmetry than that in the latter.Hence,the influence of crystal field symmetry dominated luminescence efficiency rather than crystallinity because the luminescence intensity observed in Eu0.05Y0.95PO4 synthesized with 1.0 g urea was six-fold higher than that of the as-synthesized sample.With increased concentration of Eu 3+ ion,the luminescence intensity initially increased,and then subsequently decreased as the concentration of Eu 3+ ion exceeded 12 mol.%due to concentration quenching.The optimal condition for YPO4:Eu 3+ phosphor was Eu0.12Y0.88PO4 with 1.0 g urea added in the precursor.The luminescence intensity of the optimal condition was again enhanced 1.6-fold relative to that of Eu0.05Y0.95PO4 synthesized with 1.0 g-urea.     

Broadband downconversion in YVO4：Tm3＋,Yb3＋ phosphors

An efficient near-infrared (NIR) downconversion (DC) by converting broadband ultraviolet (UV) into NIR was demonstrated in YVO4:Tm3+,Yb3+ phosphors. The phosphors were extensively characterized using various methods such as X-ray diffraction, photoluminescence excitation, photoluminescence spectra and decay lifetime to provide supporting evidence for DC process. Upon UV light varying from 260 to 350 nm or blue light (473 nm) excitation, an intense NIR emission of Yb3+ corresponding to transition of 2F5/2→2F7/2 peaking at 985 nm was generated. The visible emission, the NIR mission and the decay lifetime of the phosphors of various Yb3+ concentrations were investigated. Experimental results showed that the energy transfer from vanadate group to Yb3+ via Tm3+ was very efficient. Application of the broadband DC YVO4:Tm3+,Yb3+ phosphors might greatly enhance response of siliconbased solar cells.     

Effect of gadolinium incorporation on optical characteristics of YNbO_4：Eu~（3＋） phosphors for lamp applications

Eu3+-doped (Y,Gd)NbO4 phosphor was synthesized by solid-state reaction for possible application in cold cathode fluorescent lamps. A broad absorption band with peak maximum at 272 nm was observed which was due to the charge transfer between Eu3+ ions and neighboring oxygen anions. A deep red emission at the peak wavelength of 612 nm was observed which could be attributed to the 5D0→7F2 transition in Eu3+ ions. The highest luminance for Y1-x-yGdyNbO4:Eux3+ under 254 nm excitation was achieved at Eu3+ concentration of 18 mol.% (x=0.18) and Gd3+ concentration of 8.2 mol.% (y=0.082). The luminance of Y0.738Gd0.082NbO4:Eu3+0.18 was higher than that of a typical commercial phosphor Y2O3:Eu3+ and the CIE chromaticity coordinate was (0.6490, 0.3506), which was deeper than that of Y2O3:Eu3+. The particle size of the synthesized phosphors was controlled by the NaCl flux and particle size as high as 8 μm with uniform size distribution of particles was obtained.     

Eu3+-Sm3+稀土配合物的合成与性能表征

合成了Eu3+、Eu3+-Sm3+稀土配合物,采用红外光谱、X-射线衍射对稀土配合物的组成和结构进行了表征,通过热分析表征了配合物的热性能,荧光分析测试了配合物的激发光谱和发射光谱。结果表明,Eu3+、Eu3+-Sm3+稀土配合物Eu3+的特征荧光发射,Sm3+的引入使得Eu3+的发光强度减弱。     

微波辅助液相沉淀法合成Ca(MoO4)1-x(WO4)x:Eu3+红色荧光粉

以尿素为沉淀剂,采用微波辅助液相沉淀法合成了类球状双基质Ca(MoO₄)_1-x(WO₄)_x:Eu3+红色荧光粉,通过采用XRD、SEM、荧光光谱(PL)等现代分析技术对荧光粉的结构、形貌及发光性能进行了表征.结果表明,制备的Ca(MoO₄)_1-x(WO₄)_x:Eu3+红色荧光粉晶型完整,纯度高,为白钨矿结构;掺杂WO₄2-离子后,CaMoO₄:Eu3+红色荧光粉的发光性能明显增强,当WO₄2-离子的掺杂量x=0.4时,在395 nm激发下,在616 nm处的主发射峰的发光强度达到最大,掺杂浓度过高时会出现浓度淬灭现象.其较优的煅烧温度为1 000 ℃,煅烧时间为4 h.      

Properties of red-emitting phosphors Sr2MgSi2O7:Eu3+ prepared by gel-combustion method assisted by microwave

Novel red-emitting phosphors Sr2MgSi2O7:Eu3+ were prepared by gel-combustion method assisted by microwave. The phase struc-ture and luminescent properties of as-synthesized phosphors were investigated by XRD and fluorescence spectrophotometer, respectively. The results showed that the as-synthesized sample was Sr2MgSi2O7 with tetragonal crystal structure. The excitation spectrum of Sr2MgSi2O7:Eu3+ was composed of two major parts: one was the broad band between 200 and 350 nm, which belonged to the charge transfer of Eu3+-O2-; the other consisted of a series of sharp lines between 350 and 450 nm, ascribed to the f-f transition of Eu3+. The emission spec-trum consisted of two emission peaks at 593 and 616 nm, which was attributed to 5D0→7F1 and 5D0→7F2 of Eu3+, respectively. The concen-tration of Eu3+ (x) had great effect on the emission intensity of Sr2-xMgSi2O7:Eu3+x. When x varied in the range of 0.04-0.18, the intensity of emission peaks at 593 and 616 nm increased gradually with the concentration of Eu3+ increasing. It was interesting that no concentration quenching occurred. Moreover, the luminescent intensity could be greatly enhanced with incorporation of charge compensator Li+ ions.