Y2Zr2O7：Eu^3＋纳米微粒的合成与变温发光特性研究

采用低温燃烧法制备了Y2Zr2O7:Eu3+纳米微粒,用XRD和HRTEM对纳米微粒的结构、形貌进行了分析和表征.作为对比,采用高温固相法制备了Y2Zr2O7:Eu3+体相材料,对其变温发光特性进行了测试和对比研究.结果表明,Y2Zr2O7:Eu3+纳米晶的606和628nm发射(5D0→7F2)最强,与5D0→7F1磁偶跃迁相对发光强度较体相材料增强60%,且随着温度的降低,Eu3+离子5D0→7FJ(J=1,2,3,4)跃迁发光强度均有变化.另外,采用盐酸"浸蚀"技术对Y2Zr2O7:Eu3+纳米微粒进行了表面处理,室温发射光谱测试表明:5D0→7F2,3,4电偶跃迁与5D0→7F1磁偶跃迁的相对强度较表面处理前减小约15%.对观测到的结果通过纳米微粒的表面效应和激活离子所处局域环境的变化进行了定性解释和讨论.     

微波水热合成球形Al_2O_3：Eu~（3＋）及发光性能研究

采用微波水热法制备Al2O3∶Eu3＋红色发光材料。通过XRD、SEM和荧光光谱对系列样品的物相、形貌、发光性质进行表征。XRD测试结果表明合成的样品为γ-Al2O3;SEM显示样品形貌为片组装成的微球;光致发光测试表明,Al2O3∶Eu3＋的发射以594nm的5 D0→7F1磁偶极跃迁为主,最佳激发波长为394nm。随着掺杂浓度的增大,样品5 D0→7F2电偶极跃迁强度变大,掺杂量为0.09%（摩尔分数）的样品在618nm的5 D0→7F2电偶极跃迁强度明显提高。     

Eu掺杂纤维状Sr_2SiO_4的合成与发光性能

采用凝胶-燃烧法合成了Sr2SiO4∶Eu3+红色荧光粉,利用XRD、SEM、PL对样品进行了结构、形貌及发光性能表征。结果表明,所得样品为单斜晶系结构,呈粒径为0.1～0.3μm、长1μm左右的纤维状小颗粒。在波长394nm的紫外激发下,样品发射光谱由位于红光区的5个主要荧光发射峰组成,峰值分别位于578nm、590nm、612nm、650nm和700nm,对应Eu3+的5 D0→7F0、5 D0→7F1、5 D0→7F2、5 D0→7F3和5 D0→7F4特征跃迁发射,612nm处的发射最强,是一种适用于白光LED的红色荧光粉。     

低温单斜相BiPO_4∶Tb~(3+)纳米晶的合成及其发光性能

以无水乙醇为反应溶液,采用室温共沉淀制备了低温单斜相BiPO4∶Tb3+绿色荧光纳米材料,并进行高温烧结处理。利用X-射线衍射(XRD)、透射电镜(TEM)和荧光光谱分别对所得样品的相结构、形貌以及发光性能进行研究。结果表明:通过高温烧结,样品没有发生晶型转变,仍然保持单斜相结构和纳米颗粒形貌。同时,Tb3+离子作为绿色发光中心进入到BiPO4的晶格中取代Bi 3+的格位,在370nm激发下,观察到Tb3+离子的特征跃迁(5D4→7FJ,J=6~3),其中以5D4→7F5跃迁发射(543nm)为主;并考察了BiPO4∶Tb3+纳米晶发光强度随Tb3+掺杂量的变化关系,发现其淬灭浓度高达20mol%。     

新型黄绿色发光材料Sr2MgSi3O9:Ce3+,Tb3+的合成及光谱分析

采用凝胶-燃烧法在活性炭弱还原气氛下成功合成了新型荧光粉Sr2MgSi3O9 :Tb3+、Sr2MgSi3O9:Ce3+,Tb3+,用X射线粉末衍射仪(XRD)、扫描电镜(SEM)、荧光分光光度计等对合成产物进行了分析和表征.结果表明,所合成的发光材料与Sr2MgSi2O7具有相似的晶体结构,同属四方晶系.样品一次颗粒近似球形,粒径在100nm左右.Sr2MgSi3O9:Tb3+的激发光谱为一位于249nm的宽带,发射光谱主要由473、491、547、585nm等一系列发射峰组成,其中473nm(5D3→<7F3)为主发射峰,547nm(5D4→7F5)为次发射峰;样品Sr1.955MgSi3O9:Tb3+0.04,Ce3+0.005的激发光谱由峰值分别位于249和335nm的双激发带组成,其中后者为主激发带.在335nm激发下,其发射光谱由两部分组成,其中400nm附近的带状发射对应于Ce3+的发射,而491、547、588nm处的发射峰归属为Tb3+的5+D4→7FJ(J=6,5,4)跃迁发射,最强峰位于547nm,对应Tb3+的5D4→7F5跃迁.此外,探讨了Ce3+掺杂量对样品发光亮度的影响,发现Ce3+可以把能量传递给Tb3+,对Tb3+起到敏化作用.     

ZnAl2O4：Eu^3＋红色发光材料的燃烧法合成与光谱性能研究

采用燃烧法在550℃合成了红色纳米发光材料ZnAl2O4：Eu^3＋，并用X射线粉末衍射对其结构进行了表征。XRD分析证实样品具有尖晶石结构的ZnAl2O4相。测定了样品的激发光谱和发射光谱，光谱数据表明：对应于Eu^3＋的。^5D0→^7F2跃迁的发射强度。^5D0→^7F0,1,3,4跃迁的发射强度，ZnAl2O4：Eu^3＋ 形成红色发光材料,推测是由于基质结构的不对称性，Eu^3＋在基质ZnAl2O4中占据非对称中心的格位所致。并考察了不同退火温度处理后，样品Eu^3＋的^5D0→^7Fj跃迁辐射变化情况。     

铽掺杂氟化铈微纳米材料的水热合成与荧光性质

以氯化铈和氟化钠为原料制备铽掺杂的氟化铈纳米颗粒,采用水热法,在不同保温时间下制得3种样品。通过X-射线衍射仪(XRD)、扫描电子显微镜(SEM)、紫外-可见光谱仪(UV)、荧光光谱仪(PL)对样品进行表征。XRD分析结果表明:制备的CeF3:Tb3+纳米颗粒为六方晶系结构,SEM证实不同的保温时间,样品的形貌差别较大。在310nm的光激发下,350nm处宽而强的发射峰对应三价Ce3+离子的特征发射峰,位于540nm处来源于Tb3+离子的特征发射(5 D4-7F5),在482nm处的发射峰对应于Tb3+离子的5 D4-7F6的跃迁。     

一种新型红色长余辉材料的制备及其发光性能

采用高温固相法制备出Sr3Al2O6∶Eu3x+红色荧光材料,可被可见光激发。在392和463nm激发下的线状发射峰,可归属为Eu3+离子的5DJ(J=0,1,2,3)→7FJ(J=0,1,2,3,4,5)跃迁,以612和617nm附近对应于5D0→7F2的电偶极跃迁发光最强。随着Eu3+掺杂量的增加,612nm附近发射峰相对减弱,而617nm处的发射峰相对增强,当x值为0.16时,样品发光强度最大。将所制样品与蓝、紫色长余辉材料混合,在停止光照后,利用长余辉材料所发出的光作为激发光源,使样品能够继续发射红光,从而得到一种新型的红色长余辉材料。     

纳米Y2O2S∶Tb X射线发光粉的合成及发光性质

以EDTA为螯合剂、尿素为沉淀剂,采用络合沉淀法制备了Y2O2S:Tb纳米X射线发光粉.通过X射线衍射(XRD)、光致发光(PL)光谱和X射线激发发光(XEL)光谱对纳米发光粉进行了表征,并研究了纳米晶的发光性能及Tb3+离子的能量传递过程.研究表明:所制备样品显示了单一的六角结构,其一次粒径约为32nm.在254nm紫外光和X射线激发下,Y2O2S:Tb X射线发光粉都显示了Tb3+离子的特征发射峰,分别起源于5D3和5D4能级到基态能级的跃迁.     

纳米Y2O2S:Tb X射线发光粉的合成及发光性质

以EDTA为螯合剂、尿素为沉淀剂,采用络合沉淀法制备了Y2O2S:Tb纳米X射线发光粉.通过X射线衍射(XRD)、光致发光(PL)光谱和X射线激发发光(XEL)光谱对纳米发光粉进行了表征,并研究了纳米晶的发光性能及Tb3+离子的能量传递过程.研究表明:所制备样品显示了单一的六角结构,其一次粒径约为32 nm.在254 nm紫外光和X射线激发下,Y2O2S:Tb X射线发光粉都显示了Tb3+离子的特征发射峰,分别起源于5D3和5D4能级到基态能级的跃迁.     

Luminescent properties of La3PO7:Eu3+ nanoparticles

La3PO7:Eu3+ samples were prepared by combustion and annealing and characterized by X-ray diffraction and transmission electron microscopy. It was found that the average size of the particles is about 80 nm. The red emission from the 5D0 --> 7F2 transition of the Eu3+ ions under ultraviolet light excitation is much stronger than the orange emission from the 5D0 --> 7F1 transition. The emission spectra, charge transfer band, laser selective excitation spectra, and time-resolved spectra indicate that symmetry of the local environment of Eu3+ lacks an inversion center and Eu3+ ions occupy at least two types of sites in the La3PO7 crystal. The superior color chromaticity compared to other phosphates and borates doped with Eu3+ means La3PO7:Eu3+ may have potential as a luminescent material.     

Study on luminescence behavior of BaAl12O19:Tb, Eu

BaAl12O19:Tb, Eu phosphors were prepared by sol-gel technique. The luminescence properties and the energy transfer between Eu2+ and Tb3+ were investigated. For BaAll2O19:Tb phosphor, the strongest excitation peak and emission peak produced from Tb3+ transition of 5D4-7F5 were at 240 nm and at 550 nm respectively, while the peak shape was narrow and peak intensity was large. The Eu2+ added in the BaAl12O19:Tb induced energy transfer to Tb3+ and different color luminescence from blue (400 nm) to green (570 nm) was obtained by changing the ratio of Tb3+/Eu2+ with excitation at 240 nm.     

The sol-gel process synthesis of GdAl3(BO3)4:Eu3+ nanophosphors

GdAl3(BO3)4:Eu3+ red phosphors were prepared using citric acid as complex agent by sol-gel technique. The preparation conditions of the precursor synthesis, including crystallization temperature and crystallization time were investigated. Their structure and luminescence properties were characterized by X-ray diffraction (XRD) analysis and fluorescence spectrometry. The results showed that GdAl3(BO3)4:Eu3+ phosphor crystallized at 960 degrees C for 2 h have been synthesized by sol-gel method. The phosphor is distributed into hexagonal system and the lattice parameters are a = 9.2992 nm c = 7.2577 nm. The excitation spectrum of Gd(0.95)Al3(BO3)4:Eu(0.05)3+ samples is complex and the frequency scale is wide. It consists of a number of main excitation transitions namely 8S(7/2) --> 6IJ (270 nm) of Gd3+, and the others 7F0 --> 5L6 (400 nm), 7F0 --> 5D2 (472 nm) and 7F0 --> 5D1 (542 nm) of Eu3+. The main emission peaks are 614 nm and 619 nm, which are the characteristic emission peaks of Eu3+. These emission peaks correspond to the transition from 5D0 to 7F2 of Eu3+. The shape and the wavelength range of the emission spectrum are similar when the sample was excited by different excitation spectrum. Only the relative intensity of the emission peaks is different from each other.     

Characterization and luminescence of Eu3+ ions doped 12CaO 7Al2O3 nanopowders

Eu3+ ions doped 12CaO 7Al2O3 (C12A7) powders with different Eu3+ concentrations were prepared by sol-gel combined with solid state reaction method. The results of XRD and Raman spectra showed that single cubic phase polycrystalline C12A7:Eu3+ powders were prepared. The absorption peaks attributed to f-f transition of Eu3+ ion can be observed, indicating that Eu3+ had been incorporated into C12A7 lattice site. Visible PL peaks around 578, 588, 614 nm were ascribed to 5D0 --> 7FJ (J = 0, 1, 2) transitions of Eu3+ under the excitation of 488 nm line. The PL of C12A7:Eu3+ showed the strongest emission intensity at Eu3+ concentration of 0.5 at%. Two different types of Eu3+ centers were identified by the two lines from 5D0 --> 7F0 transition emission. The doping mechanism of C12A7:Eu3+ might be attributed to Eu3+ ions substitution for two types of Ca2+ lattice sites in C12A7. The temperature dependent PL spectra of Eu-doped C12A7 were measured in the range from 100 to 300 K under the excitation of 488 nm laser line. The PL intensities as a function of temperature were well fitted by using a unified theoretical model, considering thermal activation and nonradiative energy transfer processes.     

钼酸锶红色荧光粉的燃烧合成及其表征

采用燃烧法合成了SrMoO4:Eu3+红色荧光粉,用X射线衍射(XRD)和荧光光谱对其结构和发光性能进行了表征。研究了燃烧温度、保温时间、Eu3+和电荷补偿剂Na+浓度对荧光粉发光性能的影响,确定了燃烧合成SrMoO4:Eu3+红色荧光粉的优化工艺参数。SrMoO4:Eu3+荧光粉样品的激发光谱在200～350nm之间有一个宽带主激发峰和分别在近紫外394nm、蓝光465nm处有2个次激发峰,其红光发射峰位于617nm处。     

Temperature-Dependent Luminescence Characteristic of SrSi2O2N2：Eu2＋ Phosphor and Its Thermal Quenching Behavior

The yellow SrSi2O2N2：Eu2＋ phosphor has been synthesized by using a simple solid-state reaction method with Sr2SiO4：Eu2＋ as the precursor. It shows a broad excitation band extending from 250 to 520 nm and an asymmetric emission band with a main peak at about 550 nm. The emission intensity of the SrSi202N2：Eu2＋ is about 1.2 times higher than the commercial yellow phosphor YAG：Ce3＋ （P46-Y3）. The temperature- dependent luminescence characteristic of SrSi202N2：Eu2＋ has been investigated in this paper. With increasing temperature, the emission band of SrSi202N2：Eu2＋ shows anomalous blue-shift along with decreasing emission intensity and the broadening full width at half maximum （FWHM）. Particularly, compared with YAG：Ce3＋ （P46-Y3）, the yellow SrSi202N2：Eu2＋ phosphors exhibit higher thermal stability due to their weaker electron-phonon coupling strength （1.1）, lower stokes shift （0.0576 eV） and larger activation energy （0.288 eV）. All these results indicate that SrSi202N2：Eu2＋ yellow phosphors have potential application for white light-emitting diodes （LEDs）, What＇s more, an energy level scheme is constructed to explain the anomalous blue-shift phenomenon.     

Luminescence properties of nano-crystalline Ba3MgSi2O8:Eu2+, Mn2+ phosphors

Ba3MgSi2O8:Eu2+, Mn2+ phosphors were synthesized by the sol-gel method and high temperature solid-state reaction method, respectively. XRD (X-ray diffraction), FT-IR (Fourier transform infrared spectroscopy), PL (photoluminescence spectra), and PLE (photoluminescence excitation spectra) were measured to characterize the samples. Emission and excitation spectra of our Ba3MgSi2O8:Eu2+, Mn2+ phosphors monitored at 441, 515, and 614 nm are depicted in the paper. The emission intensities of 441 and 515 nm emission bands increase with increasing Eu2+ concentration, while the peak intensity of the 614 nm band increases with increasing Mn2+ concentration. We conclude that the 515 nm emission band is attributed to the 4f(6)5d transition of Eu2+ ions substituted by Ba2+ sites in Ba2SiO4. The 441 nm emission band originates from Eu2+ ions, while the 614 nm emission band originates from Mn2+ ions of Ba3MgSi2O8:Eu2+, Mn2+. Nano-crystalline Ba3MgSi2O8:Eu2+, Mn2+ phosphors prepared by the sol-gel method show higher color rendering and better color temperature in comparison with the samples prepared by high temperature solid-state reaction method.     

Preparation and luminescent properties of YVO4:Eu3+ nanofibers by electrospinning

This paper describes a procedure based on electrospinning for generating europium-doped yttrium vanadate (YVO4:Eu3+) nanofibers with diameters ranging from 30 to 50 nm. The YVO4:Eu3+ nanofibers were obtained through calcining precursory nanofibers, which were prepared through the electrospinning method. Suitable electrospinning parameters, such as concentration of PVP in solution, spinneret tip-to-collector plate distance (TCD), and applied voltage between spinneret and collector plate, are used to obtain thinner and more uniform precursory nanofibers of YVO4:Eu3+, which is important for preparing smaller diameter pure YVO4:Eu3+ nanofibers. The luminescent properties of the YVO4:Eu3+ nanofibers including excitation and emission spectra and fluorescence lifetime were studied. The excitation spectrum shows a broad band extending from 200 to 350 nm, which corresponds to the strong vanadate absorption in YVO4:Eu3+. The emission spectrum is dominated by the red 5D0 --> 7F2 hypersensitive transition of Eu3+. The fluorescence lifetime of Eu3+ 5D0 --> 7F2 (619 nm) is determined to be 493 micros at room temperature, which is basically in accordance with that in the bulk (521 micros).     

Study on luminescent properties of Eu3+ doped new type yttrium tungsten oxide nanophosphors

In this paper, a novel nanophosphor, Y10W2O21:Eu, was synthesized through co-precipitation which is a simple and low-costing method. The structure and morphology of the nanocrystal samples were characterized by using XRD and FE-SEM. The emission spectra, excitation spectra and fluorescence decay curves were measured. J-O parameters, quantum efficiencies of Eu3+ 5D0 energy level, color coordinates and Huang-Rhys factor of Y10W2O21:Eu nanophosphors were calculated. The results indicate that EU3+ 5D0-7F2 red luminescence at 610 nm can be effectively excited by 394 nm near-UV light and 464 nm blue light in Y10W2O21 host, which is similar to the familiar Eu3+ doped tungstate phosphors (e.g., Gd2(WO4)3:Eu, CaWO4:Eu). Besides, compared with the other types of tungstate phosphors, a less expensive tungsten was used, which can effectively reduce cost. Therefore, the Y10W2O21:Eu red nanophosphors may have a potential application for white LED.     

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%.