弱碱溶液后处理对固相合成铈掺杂钇铝石榴石荧光粉发光性能的改进

为改善高温固相反应制备的铈掺杂钇铝石榴（YAG∶Ce3+）黄光荧光粉的发光性能,分别采用浓氨水、N,N-二甲基乙酰胺(DMAC)、三乙醇胺、聚丙烯酰胺和六次甲基四胺等的水溶液对其进行浸泡处理,比较了处理剂浓度、用量和处理剂类型对荧光粉发光强度、荧光粉温度、猝灭性能和形貌的影响,确定了以30%氨水在50 ℃浸泡50 min为优化的处理工艺,YAG∶Ce3+荧光粉发光强度比处理前约提高9.5%,荧光粉分散程度也得到改善,处理后粒径分布更加均匀。     

NaF助熔剂对Sr2MgSi2O7:Eu2+,Zr4+荧光粉结构及发光性能影响

在还原性气氛下采用高温固相法合成了适合近紫外(λex=375 nm)激发的光致发光蓝色荧光粉Sr2MgSi2O7:Eu2+,Zr4+,研究了NaF助熔剂对Sr2MgSi2O7:Eu2+,Zr4+荧光粉晶体结构、颗粒形貌及发光性能影响。结果表明:适量的NaF助熔剂有利于样品的晶化,所获得样品的颗粒形貌更加规整,能有效降低中间粒径(D50)并控制粒径分布;只含中间颗粒(D50)样品的发光强度高于含全颗粒样品的发光强度;NaF助熔剂最佳添加含量为6%(质量分数),可使样品的发光强度提高446%;掺杂适量的Zr4+有利于样品的发光强度的提高,最后探索NaF助熔剂及掺杂Zr4+离子提高发光性能的机制。     

银纳米颗粒对CaSrSiO_4:Tb~(3+)光致发光性能的影响

采用高温固相反应法制备了系列的Ag, Tb~(3+)单掺和共掺CaSrSiO_4纳米荧光粉。XRD和SEM分析结果表明, Tb~(3+)和Ag颗粒的掺入对纳米粉末晶体结构的影响较弱,但CaSrSiO_4:0.7Tb~(3+),0.1Ag样品呈现了立方体结构,且颗粒尺寸明显增大。XPS结果显示Ag单质和Ag~+共存于荧光粉中。在243 nm激发下,同时观测到强的545, 415和381 nm的光致发光谱,以及较弱的437, 586和624 nm发光峰。掺入0.1%(摩尔分数)Ag纳米颗粒时,能够使CaSrSiO_4:0.7Tb~(3+)纳米荧光粉的光致发光强度增强25%。最后讨论了掺Ag颗粒浓度对Tb~(3+)的545和381 nm特征峰衰减曲线的影响。     

GdAlO_3:Er~(3+),Yb~(3+)荧光粉的制备与上转换发光性能

采用共沉淀、溶胶-凝胶和固相反应法制备了GdAlO3:Er3+,Yb3+荧光粉.借助X射线衍射、扫描电子显微镜、傅里叶变换红外光谱、N2-吸附、吸收光谱和荧光光谱等手段研究了不同方法制备的GdAlO3:Er3+,Yb3+荧光粉结构、形貌、表面基团和光吸收及上转换发光性能.结果表明:用共沉淀法比固相反应法和溶胶-凝胶法可以在更温和的条件下制得纯相GdAlO3:Er3+,Yb3+荧光粉,用共沉淀法和溶胶-凝胶法制备的GdAlO3:Er3+,Yb3+荧光粉颗粒都在纳米尺寸,溶胶-凝胶法制得的样品存在相对严重的颗粒团聚现象,而用固相反应法制备的荧光粉为微米级颗粒.GdAlO3:Er3+,Yb3+荧光粉在980 nm激发的上转换发射光谱包含波长为524和546 nm的绿光与659 nm的红光,且三种方法制备的样品绿光发射强度都显著高于红光.不同方法制备的荧光粉上转换发光强度和红光/绿光强度比相差较大,共沉淀法制备的样品上转换发光强度要显著高于固相法以及溶胶-凝胶法制备的样品,而溶胶-凝胶法制备的样品发光中红光/绿光相对强度比最高.红外光谱显示,不同方法制备的GdAlO3:Er3+,Yb3+荧光粉表面OH-、CO32-及CO2官能团含量不同,溶胶-凝胶法制备的样品要明显高些.基于红外光谱、不同Er3+和Yb3+离子掺杂浓度及不同激光功率上转换发光的结果,对Er3+和Yb3+之间的能量传递过程及不同方法制备荧光粉的上转换发光性能进行了讨论.     

Sr5(PO4)3Cl:Eu2+蓝色荧光粉合成新方法的研究

Sr5 (PO4)3Cl:Eu2+是一种重要的蓝色发射荧光材料,通常采用高温固相反应法来制备.本文利用Sr5(PO4)3(OH)与Sr5(PO4)3Cl结构相同的特点,采用沉淀法合成出羟基磷酸锶铕前体,经过氯化铵和助熔剂作用下的固相氯代反应合成出Sr5(PO4)3Cl:Eu2+荧光粉.考察了pH值与原料比例等对沉淀反应过程及产物的影响,并讨论了氯化铵作用下的氯代过程以及助熔剂对产物荧光粉形貌的作用机制.研究结果表明,本合成方法条件易控,且合成产物Sr5 (PO4)3Cl:Eu2+的物相纯度高,尺寸分布均匀,形貌规则,发光性能优良.     

高掺杂Ce,Gd(Y_(3-x-y)Ce_xGd_y)Al_5O_(12)荧光粉的发光下降及温度猝灭特性

采用高温固相法分别合成了不同Ce浓度掺杂的和固定Ce浓度为0.06不同Gd浓度掺杂的Y3Al5O12(YAG)系列荧光粉,通过测量其激发、发射光谱、漫反射光谱、荧光寿命和变温发射光谱,研究了掺杂元素的浓度对荧光粉发光性能的影响以及荧光粉发光的温度猝灭性质。研究结果表明:荧光粉发光强度随着Ce3+掺杂浓度和Gd3+掺杂浓度的提高均呈下降趋势。分析发现,荧光粉发光强度下降并非主要由浓度猝灭所引起,而是由于高浓度掺杂下发生YAG基质与Ce3+对激发光的竞争吸收,导致Ce3+对激发光的吸收量减少,从而影响发光强度。温度实验表明,随着温度的升高,荧光粉发光强度下降。Ce含量的改变对YAG:Ce荧光粉的热猝灭性质影响较小,Gd的掺杂使荧光粉的发射波长向长波方向移动,同时热猝灭现象严重。     

白光LED用荧光材料Ba3 Gd( BO3 )3:Eu3+的发光性能研究

用高温固相反应法制备了稀土离子Eu3+ 掺杂的三元稀土硼酸盐Ba3Gd(BO3)3发光材料, 通过X射线衍射 (XRD) 、荧光光谱和扫描电镜 (SEM) 等测试手段对Ba3Gd(BO3)3:Eu3+ 荧光粉的制备条件、发光性能以及形貌进行了研究. XRD结果表明, 在1000 ℃时可得到Ba3Gd(BO3)3 纯相. 扫描电镜照片显示颗粒基本为球形, 粒径约为200～400 nm. 发光光谱测试表明, Ba3Gd(BO3)3:Eu3+荧光粉在近紫外区(UV) (396 nm)和蓝光区(466 nm)可以被有效地激发, 分别用255和396 nm的紫外光激发样品时, 以Eu3+ 的 5D0-7F2 (611和616 nm) 超灵敏跃迁为主要发射峰. 当Eu3+的掺杂浓度为10%(摩尔分数)时, Ba3Gd(BO3)3:Eu3+ 在611和616 nm处的发光强度最大. 因此, 这种荧光粉是一种可能应用在白光LED上的红色荧光材料.     

Eu~(2+)、Mn~(2+)、Sr~(2+)掺杂BaMgAl_(10)O_(17)的燃烧法合成及光致发光性能（英文）

在600℃温度下,采用液相燃烧法合成了Sr~(2+)、Eu~(2+)和Mn~(2+)三掺的Ba Mg All0O17(BAM)蓝绿荧光粉。用XRD、SEM和荧光光谱仪分别分析和表征该荧光粉的物相、形貌和光致发光性能。结果表明,液相燃烧法合成BAM的温度明显低于传统的高温固相合成法;合成的纳米棒均匀、无团聚现象;荧光光谱仪分析表明Eu~(2+)、Mn~(2+)离子间存在能量传递,且Sr~(2+)能有效提高BAM的发光强度,约为固相法制备荧光强度的1.8倍。BAM:0.1Eu~(2+),0.04Mn~(2+),0.05Sr~(2+)色坐标为(0.146,0.250),属于蓝绿光。     

荧光粉Ba_(5-3x/2)B_4O_(11):xEu~(3+)的制备及发光性能

采用高温固相烧结法成功制备了Ba_(5-3x/2)B_4O_(11):xEu~(3+)(x=0. 02～0. 22)荧光粉,利用XRD和SEM等对荧光粉进行了结构和形貌表征。在激发波长为393 nm的条件下,发射峰(596、621、657和706 nm)与Eu~(3+)的5D0-7FJ(J=1,2,3,4)电子跃迁相对应,其中621 nm最强发射峰由Eu~(3+)离子5D0→7F2电偶极跃迁造成。文章还研究了Eu~(3+)掺杂浓度对Ba_(5-3x/2)B_4O_(11):xEu~(3+)发光性能的影响,结果表明,荧光粉的发光强度随着Eu3+掺杂量的增加呈现先增大后减小的趋势,Eu~(3+)最佳掺杂量为0. 16。     

形貌可控的NaCaGd(WO4)3:Eu3+红色荧光粉的制备及发光性能

采用水热法成功合成了形貌可控的NaCaGd_(1-x)(WO_4)_3∶x Eu~(3+)红色荧光粉。系统地研究了初始溶液pH值、反应温度和Eu3+掺杂浓度对NaCaGd_(1-x)(WO_4)_3∶x Eu~(3+)荧光粉物相结构、微观形貌和发光性能的影响。结果表明,当pH值为9、反应温度为180℃时,可合成单相四方晶系的NaCaGd(WO_4)_3,且颗粒微观形貌呈现分散性好、尺寸较均一的四方盘状纳米晶。在394 nm激发下,荧光粉显现典型的红光发射,其对应于Eu~(3+)的特征4f-4f跃迁。荧光粉发射光谱的强度随着pH值、反应温度及Eu~(3+)掺杂浓度的变化而变化。当pH=9、反应温度为180℃时,NaCaGd_(1-x)(WO_4)_3∶x Eu~(3+)(x=1)获得最佳发光强度。此外,研究了NaCaEu(WO_4)_3荧光粉的热稳定性,结果显示随着温度的升高,荧光粉发光强度逐渐降低。最后,通过理论计算得到荧光粉的色坐标和色纯度分别为(0.658,0.341)和96.1%,接近标准红色CIE坐标(0.673,0.327)。     

Comparative study on the synthesis, photoluminescence and application in InGaN-based light-emitting diodes of TAG:Ce phosphors

Cerium-doped terbium aluminum garnet phosphors, Tb₃Al₅O₁₂:Ce³⁺ (TAG:Ce³⁺), were prepared with different methods: co-precipitation (CP), half dry-half wet (HDHW), sol-combustion (SC) and Pechini method plus conventional solid state reaction (SS) method. Comparative study on the phase-formation, particle size, morphologies and luminescent characteristics of the phosphors synthesized with different methods was carried out by means of XRD, FE-SEM and photoluminescence (PL) analysis and SC method was confirmed by the comparison of the results to be an easy and an effective process for preparing efficient and nano-sized Tb₃Al₅O₁₂:Ce³⁺ phosphors. Various factors influencing particle size, morphology and PL of the phosphors, such as precursor preparation, reaction temperature and heating time, were also investigated. Light-emitting diodes (LEDs) were fabricated with each phosphor and a ∼460 nm emitting InGaN chip. The LEDs from SS, HDHW and CP exhibit strong white emission while those from SC and Pechini emit yellow, revealing that the emission characteristics of LEDs are influenced not only by the morphology and the particle size of the phosphors, but also by the preparing process of the phosphors.     

Effect of particle size and dopant concentration on photophysical properties of Eu3+-doped rare earth oxysulphide phosphor coatings

Europium-doped rare-earth oxysulphides (red phosphors) are often used as reference luminophore in pyrene-based pressure sensor coatings for aerodynamic applications. Different red phosphor samples were characterized for their particle size, chemical composition, photoluminescent properties and temperature sensitivity. The red phosphor samples were characterized using energy-dispersive X-ray spectroscopy (EDX) for elemental analysis and scanning electron microscopy (SEM) for morphology and particle size measurement. The particle size was in the range of 1.5-5.7 μm with morphology of hexagonal or spherical shape. It was found that phosphor with higher europium content exhibited higher luminescent emission intensity. The phosphor coatings were prepared by spraying a dispersion of the material in silicone resin. Smooth coatings were obtained by using phosphor samples with smaller particle size. Upon 334 nm excitation, the coatings showed characteristic luminescence 5D0→7FJ (J=0, 1, 2, 3, 4) of the Eu3+ ions. The electronic transition located at 626 nm (5D0→7F2) of Eu3+ ions was stronger than the magnetic dipole transition located at 595 nm (5D0→7F1). Luminescence decay curves obeyed double exponential behaviour. The phosphor samples showed temperature sensitivity of -0.012 to -0.168%/°C in the temperature range of 25-50 °C.     

白光LED用新型红色荧光粉KCaY(MoO4)3:Eu3+的制备及发光性能

采用高温固相法制备了新型KCaY1-x(Mo04)3:Eux红色荧光粉.利用X射线衍射(XRD)、扫描电镜(SEM)和荧光光谱技术对粉体进行了结构、表面形貌和发光性能表征.结果表明:该系列荧光粉均为四方晶系的白钨矿结构,能够被近紫外光(394 nm)和蓝光(465 nm)有效激发,产生Eu3的5 D0→7 F2特征跃迁红光发射(613 nm).对这种荧光粉作后处理,可改善其表面形貌,并提高其发光强度.该系列荧光粉在394,465 nm的吸收与目前广泛应用的近紫外和蓝光LED芯片的输出波长相匹配.因此这种荧光粉是一种可能应用在白光LED上的红色荧光粉材料.     

Synthesis, characterization and luminescence properties of SrLa2(MoO4)4:Eu phosphors

SrLa₂(MoO₄)₄ (SLM) phosphors doped with Eu³⁺ ions were prepared by a sol–gel combustion method using citric acid as a fuel/reductant and nitrates as oxidants. The crystallization processes were tracked by means of X-ray diffraction and thermo-gravimetric analysis and differential scanning calorimetry. The size and shape of the products were characterized using a scanning electron microscope, while the luminescent spectra of these resulting phosphors were recorded using a photoluminescence (PL) spectrophotometer. PL studies reveal that the emission intensity of SLM:Eu phosphors was strongly related to sintering temperature as well as the doping concentration of Eu³⁺ ions. The present phosphor has a strong excitation at 395 and 459 nm, indicating that it could serve as a promising red-emitting candidate for near-UV and GaN-based blue light-emitting diode chips.     

Solvothermal synthesis and characterization of Ln (Eu3+, Tb3+) doped hydroxyapatite

Luminescent Ln (Eu3+, Tb3+) doped hydroxyapatite (Eu:HAp, Tb:HAp) phosphors were successfully fabricated via the cetyltrimethylammonium bromide (CTAB)/n-octane/n-butanol/water microemulsion-mediated solvothermal process. The structure, morphology, and optical properties were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FT-IR), and photoluminescence (PL) spectra as well as the kinetic decays, respectively. The XRD results reveal that the obtained Eu:HAp and Tb:HAp show the characteristic peaks of hydroxyapatite in a hexagonal lattice structure. It is observed that the as-prepared luminescent samples exhibit rod-like morphology with well dispersed and non-aggregated size distribution. Upon excitation by UV radiation, the phosphors demonstrate the characteristic 5D 0-7F 1-4 emission lines of Eu3+ and the characteristic 5D4-7F 3-6 emission lines of Tb3+. Moreover, the photoluminescence intensities (PL) of Eu3+ and Tb3+ can be tuned by altering the solvothermal temperature and the doping concentration of Eu3+ and Tb3+.     

反相微乳液聚合法制备聚(丙烯酰胺-co-丙烯酸)pH敏感微凝胶及其性能

以丙烯酰胺(AM)和丙烯酸(AA)单体的水溶液为分散相,失水山梨醇单油酸脂(Span80)/聚氧乙烯失水山梨醇脂肪酸脂(Tween80)/异辛烷为分散介质,分别以N,N′-亚甲基双丙烯酰胺(MBA)、过硫酸铵/亚硫酸氢钠((NH4)2S2O8/NaHSO3)为交联剂和氧化还原引发剂,在30℃进行反相微乳液聚合制备了一系列不同单体摩尔百分数的P(AM-co-AA)微凝胶.通过傅立叶红外光谱、浊度法、透射电镜(TEM)和动态光散射(DLS)等测试手段分别对微凝胶特征官能团的存在、pH敏感性、微观形态、粒径大小及粒径分布等进行表征分析.结果表明,共聚物中存在AM和AA结构单元;样品的TEM照片显示在原料中AA的摩尔百分数为60%时,P(AM-co-AA)微凝胶粒子的数均粒径为90 nm左右,呈现非规则球形;DLS结果表明,P(AM-co-AA)微凝胶与PAM微凝胶相比具有较宽的粒径分布,且随原料中AA摩尔百分数增加,粒径分布逐渐变宽;P(AM-co-AA)微凝胶具有良好的pH敏感性,敏感pH值与AA的解离常数有关,通过调节pH值可以迅速控制自身体积的溶胀与收缩.     

Effect of the vanadium(V) concentration on the spectroscopic properties of nanosized europium-doped yttrium phosphates

Nanosized rare earth phosphovanadate phosphors (Y(P,V)O(4):Eu(3+)) have been prepared by applying the organic-inorganic polymeric precursors methodology. Luminescent powders with tetragonal structure and different vanadate concentrations (0%, 1%, 5%, 10%, 20%, 50%, and 100%, with regard to the phosphate content) were then obtained for evaluation of their structural and spectroscopic properties. The solids were characterized by scanning electron microscopy, X-ray diffractometry, vibrational spectroscopy (Raman and infrared), and electronic spectroscopy (emission, excitation, luminescence lifetimes, chromaticity, quantum efficiencies, and Judd-Ofelt intensity parameters). The solids exhibited very intense (5)D(0)→(7)F(J) Eu(3+) transitions, and it was possible to control the luminescent characteristics, such as excitation maximum, lifetime and emission colour, through the vanadium(V) concentration. The observed luminescent properties correlated to the characteristics of the chemical environments around the Eu(3+) ions with respect to the composition of the phosphovanadates. The Eu(3+) luminescence spectroscopy results indicated that the presence of larger vanadium(V) amounts in the phosphate host lattice led to more covalent and polarizable chemical environments. So, besides allowing for control of the luminescent properties of the solids, the variation in the vanadate concentration in the obtained YPO(4):Eu(3+) phosphors enabled the establishment of a strict correlation between the observable spectroscopic features and the chemical characteristics of the powders.     

A mesoporous template route to the low-temperature preparation of efficient green light emitting Zn2SiO4:Mn phosphors

Green light emitting Zn2SiO4:Mn phosphors have been prepared via a low-temperature solid-state reaction using mesoporous silica SBA-15 template. This mesoporous silica template method features low-temperature formation of phosphors and easy doping. The structure and morphology of the phosphors were characterized by XRD, SEM, TEM, and N2 adsorption/desorption techniques, which confirmed the single crystallinity, ordered mesostructure, closed pore channels, and elongated ropelike morphology. The luminescent properties were examined by photoluminescence spectroscopy at room temperature, and the results of fluorescence decay time measurements show non-single-exponential decay behavior and a decrease of the decay time with an increase of the Mn concentration.     

PDP用纳米BaMgAl10O17:Eu荧光粉的燃烧合成及发光性能

采用溶液燃烧合成法直接合成了PDP用纳米BaMgAl10O17∶Eu(BAM)荧光粉, 并对产物进行了XRD、TEM分析和发光性能测试. 结果表明, 合成产物由单一的BAM组成, 且结晶完好, 不存在位错、孪晶等缺陷；BAM颗粒近似球形, 平均粒径约为20 nm；在334 nm UV光激发下, 样品的发射峰值波长为450 nm, 归属于Eu2+离子的4f 65d→ 4f 7(8S7/2)宽带允许跃迁, 与稀土三基色荧光材料中的蓝色组分发光完全一致. 与高温固相法相比, 燃烧合成法具有合成温度低, 反应时间短, 所得产物纯净且颗粒细小, 发光强度高等优点.     

Mg^2＋掺杂对锂离子正极材料Li3V2（PO4）3的影响

随着市场对锂离子电池(LIB)需求的日趋增长,对电极活性物质的要求也在朝着高能量密度、低成本、安全稳定、环境友好的方向努力,其中正极材料相对负极材料的发展较为缓慢,成为制约LIB发展的瓶颈。NASICON结构的Li3V2(PO4)3属于单斜晶系,相对金属锂具有很高的电势,理论容量高达19