Eu~(3+)激活红色荧光粉的研究进展

白光LED具有体积小、能耗低、寿命长、环保等优点,是未来照明光源的发展方向。现阶段白光LED的低显色指数和高色温限制了其发展,而红色荧光粉的性能对白光LED显色指数的提高及色温的改善非常关键。介绍了国内外用Eu3+激活红色荧光粉的钼酸盐体系,硅酸盐体系,钨酸盐体系,钒酸盐体系的研究进展,指出了目前红色荧光粉存在的问题及未来的发展趋势。     

LED用的Gd2(MoO4)3:Eu3+红色荧光粉的制备和性能研究

本文利用液相沉积法合成白光LED用的Gd2(MoO4)3:Eu3+红色荧光粉,利用X射线衍射、荧光光谱以及扫描电镜进行系列表征,系统研究掺杂离子浓度、退火温度等条件对Gd2(MoO4)3:Eu3+荧光粉的发光性能影响。结果表明:当pH=7,退火温度为1100℃,Gd:Eu摩尔比例为1.8:0.2时,所合成的荧光粉为正交晶系的类白钨矿结构Gd2(MoO4)3化合物(20-0408),荧光粉在395 nm左右有高的激发效率,发射主峰位置位于615 nm是近紫外LED中一种比较有应用价值的红色荧光粉。     

阳离子置换在白光LED灯用荧光粉中运用的研究进展

根据目前LED实现白光的两种主流方式:近紫光LED芯片+红/绿/蓝三基色荧光粉和蓝光LED芯片+黄色荧光粉(或+绿色/红色荧光粉),本文重点从黄色荧光粉、绿色荧光粉、红色荧光粉及蓝色荧光粉四个方面综述了利用阳离子置换实现对白光LED灯用荧光粉发光性能改善的研究进展,并对利用该方法对荧光粉的发光性能改善的研究趋势进行了展望。     

白光LED用Eu掺杂钨、钼酸盐红色荧光粉的研究进展

详细介绍了近几年来白光LED用Eu掺杂钨、钼酸盐红色荧光粉的制备方法:高温固相法、溶胶—凝胶法、水热法、共沉淀法等。总结了这几种方法及钨、钼酸盐红色荧光粉的优缺点,并对高发光效率样品的制备提出了一些可行研究方案。     

钨/钼酸盐体系红色荧光粉合成方法的研究与发展

红色荧光粉是白光发光二极管(LED)照明应用中的一种关键发光材料,有效改善红色荧光粉的发光性能对制造出高显色指数、低色温、大功率白光LED起到重要作用。荧光粉的合成工艺是影响红粉的表面形貌和光学性能的因素之一。本文以钨/钼酸盐基红色荧光粉为依托,对近年来红粉合成工艺的应用和研究进行了简要分析,详细介绍了国内外制备钨/钼酸盐红色荧光粉的合成方法,如高温固相法、溶胶-凝胶法、沉淀法、水热法、喷雾热解法、燃烧法等的研究现状,讨论了不同制备方法的生产流程、工艺特点以及相关制备技术参数对合成荧光粉性能的影响,并对其未来在计算机模拟、现代技术辅助以及机理研究等方面的发展方向进行了展望。     

近紫外激发单一基质荧光粉的研究进展

白光LED （light-emitting diode）因其优异的发光性能被誉为是第四代固体照明光源。本文以量子效率作为核心参数,以暖白光为最终目标,分别对蓝、绿、红三基色稀土掺杂无机荧光粉和单一基质单掺、共掺、多掺的暖白光荧光粉的研究现状进行调研。结果表明,高量子效率的近紫外激发蓝色荧光粉其激活离子主要为Eu²⁺、Ce³⁺,绿色荧光粉为Tb³⁺和Eu²⁺,红色荧光粉为Eu³⁺和Eu²⁺。现有的单一基质暖白光荧光粉仍然存在诸多技术瓶颈,如：红光不足、显色指数偏低、量子效率偏低等。基于此,建议从已有的高效红粉出发制备单一基质白光荧光粉,以消除光谱中缺乏红色成分这一难题,并适当引入除Mn之外的过渡金属元素,同时加强对基质动力学理论,以及基质和稀土之间的电子耦合作用动力学理论的研究,期望能实现稀土掺杂无机荧光粉的设计计算与可控制备。     

白光LED用新型荧光粉的探索

白光LED具有效率高、寿命长、响应快、安全、环保等优点,被誉为继白炽灯、荧光灯和高强度气体放电灯后的“第四代照明光源”.白光LED用荧光材料的制备及其发光性能的研究已成为半导体照明领域的一个热点.本文主要从蓝光芯片激发和近紫外光芯片激发的角度分别介绍了钼酸盐红色荧光粉和单一基质白光荧光粉的研究概况.     

白光LED用Ca_6Sr_4(Si_2O_7)_3Cl_2:Ce~(3+),Eu~(2+),Sm~(3+)荧光粉的合成及其发光性质

采用传统的高温固相法合成了Ce3+,Eu2+,Sm3+离子分别单激活和三种稀土离子共激活的Ca6Sr4(Si2O7)3Cl2荧光粉,并通过X射线粉末衍射、荧光光谱和CIE色坐标对其结构和发光性质进行了研究。荧光粉Ca5.91Sr3.96(Si2O7)3Cl2:0.02Ce3+,0.04Eu2+,0.04Sm3+在365 nm激发下能发射高强度白光,其色坐标为x=0.2183,y=0.2187,有望成为一种新型白光LED灯用荧光粉。     

CaMoO4:Eu3+红色荧光粉的制备及光谱分析

采用溶胶—凝胶法合成了CaMoO4:Eu3+白光LED用红色荧光粉。用XRD和荧光光谱对物相结构、发光性能进行了分析,XRD表明Mg2+,Sr2+,Ba2+部分取代Ca2+后,只有Sr2+的取代能形成连续固溶体;荧光光谱分析表明样品在220～490 nm范围内存在基质电荷迁移吸收带和Eu3+离子f-f跃迁吸收带两个较强的能量吸收带。通过光谱拟合分析了CaMoO4:Eu3+激发光谱能量吸收带的组成,研究表明通过选择不同的掺杂离子,从而改变吸收波长,可以制备出适应于不同激发波长LED芯片的荧光粉。     

白光LED用Ca0.5-yWO4∶Eu3+0.25,Li+0.25,Sm3+y红色荧光粉的合成及发光特性

采用固相法制备了白光LED红色荧光粉Ca0.71WO4∶Sm3+0.04,Li+0.25和Ca0.5-yWO4∶Eu3+0.25,Li+0.25,Sm3+y(y=0.00,0.02,0.04,0.06),通过X射线衍射(XRD)、荧光分光光度计以及稳态/瞬态荧光光谱仪研究了荧光粉样品的物相、Sm3+的掺杂量对荧光粉发光性能以及荧光寿命的影响.XRD分析表明,合成的样品均为白钨矿结构.荧光光谱表明,所合成的系列荧光粉均可以被近紫外光(393 nm)和蓝光(464 nm)有效激发,其发射主峰位于615nm处,归属于Eu3+的5D0→7F2跃迁.发光衰减曲线表明,Sm3+的掺杂对荧光粉Ca0.5WO4∶Eu3+0.25,Li+0.25荧光寿命没有影响.实验结果表明,在系列Ca0.5-yWO4∶Eu3+0.25,Li+0.25,Sm3+y荧光粉中Sm3+的最佳掺杂量为4％(摩尔分数).     

白光LED用荧光粉的研究进展

白光LED被誉为第四代照明光源,有着显著的节能前景和庞大的应用市场,荧光粉光转换型是未来白光LED发展的主流方向。本文重点介绍了蓝光芯片激发的黄色,绿色和红色荧光粉以及紫光芯片激发的红色,绿色荧光粉的研究进展,和该领域存在的问题及其发展趋势。     

Tunable chromaticity and high color rendering index of WLEDs with CaAlSiN3:Eu2+ and YAG:Ce3+ dual phosphor-in-silica-glass

Phosphors-in-glass (PiG), which serves as a potential bi-replacement of both phosphors and organic encapsulants in high-power white light-emitting diodes (WLEDs), has captured much attention due to its high thermal stability and excellent luminescent properties. However, due to the high-temperature sensitivity and the chemical reactions between phosphors with glass matrix, a variety of phosphors, especially red phosphors could be hardly dispersed into the glass without thermal quenching and decomposition, which greatly limits the improvement of color rendering index and chromaticity tunability of the WLEDs. In this study, adopting the mesoporous silica (FDU-12) and commercial phosphors as raw materials, the phosphors-in-silica-glasses (PiSGs) embedded with red phosphor CaAlSiN₃:Eu²⁺ and yellow phosphor YAG:Ce³⁺ have been successfully prepared at low sintering temperature (950°C) and short preparation time (10 minutes) using spark plasma sintering. Owing to the well preservation of the originally emissive properties of the embedded phosphors, the warm WLEDs with tunable chromaticity and exhibited a superior performance with LE of 133 lm/W, CCT of 3970 K and CRI of 81 were fabricated by encapsulating the as-prepared PiSGs on the blue chips. Moreover, the PiSG composite exhibits a high thermal conductivity up to 1.6 W/m·K.     

Particle Size Effect on the Packaging Performance of YAG:Ce Phosphors in White LEDs

The synthesis of cerium-doped yttrium aluminum garnet (YAG:Ce) phosphor of different sizes with uniform size distribution was carried out using solid-state reaction followed by grinding and sieving method. The effect of particle size distribution of YAG:Ce phosphors on the photoluminescence (PL) properties was investigated. The results demonstrate that the uniform size distribution and particle size affects the packaging performance in white light emitting diode (LED) applications. The YAG:Ce phosphors with different particle sizes were packaged in white LEDs using different amounts of each phosphors in order to get similar efficiency as that of commercially available YAG:Ce phosphors. It was observed that minimum amount of phosphor material is required for smaller particle size for getting the similar efficiency as that exhibited by commercially available YAG:Ce phosphors. The results are particularly interesting in view of reducing the cost of current LEDs by lowering the amount of phosphors without compromising the efficiencies of final LED package. A systematic study of YAG:Ce phosphors on the packing performance in white LEDs is reported.     

In-doped LiCa2.98MgV3O12 rare-earth-free phosphor with a high photoluminescence quantum yield of 67.4%

Rare earth resources applied in numerous novel materials, are increasingly scarce in worldwide. Meanwhile, great attention has been focused on the blue rare-earth-free fluorescent phosphors as an excitation source of near-ultraviolet (NUV) chips, which are available in white-light-emitting diodes (WLEDs) that combined with yellow commercial phosphors. Many solutions have been found to improve the photoluminescence quantum yield (PLQY) of phosphor. In this study, we effectively increased PLQY by introducing indium ion to vanadate garnet phosphor forming a series of LiCa_3−XMgV₃O₁₂: xIn³⁺ (x = 0.01, 0.02, 0.04, 0.06, 0.08, and 0.10). The resultant In-doped vanadate garnet phosphors exhibit a relative increase in PLQY, and the optimal phosphors is LiCa_2.98MgV₃O₁₂: 0.02In³⁺ with a PLQY as high as 67.4%. These In-doped vanadate garnet phosphors have a broad emission at 480 under 320 nm where near UV-light excitation. It is revealed that the distortion of V-V and V-O bond length in [VO₄] crystal structure and unit cell volume data of phosphors have an extensive influence on PLQY. Therefore, these novel vanadate garnet phosphors can be the essential blue color choice for WLED devices application in illumination.     

高显色白光LED用YAG：Ce^3＋，Ln^3＋荧光粉的研究进展

综述了YAG：Ce荧光粉的制备方法,着重介绍了高显色白光LED用YAG：Ce^3＋,Ln^3＋（Ln=Sm,Pr,Gd,Tb）荧光粉的最新研究进展和发光性能。YAG：Ce^3＋,Ln^3＋荧光粉的发射谱带发生红移,或在红光区增加尖锐的红光发射峰,从而提高了白光LED的显色性能。     

白光LED用硅基氮(氧)化物荧光转换材料的研究进展

硅基氮(氧)化物荧光转换材料的结构由SiX_4(X=O,N) 四面体形成的网络组成,具有优异的热和化学稳定性以及优良的荧光性能,成为白光LED的理想下转换荧光材料.本文在综述了硅基氮(氧)化物材料体系和荧光性能的基础上,分析和讨论了硅基氮(氧)化物荧光发光材料的发光机理与性能改进.最后展望了硅基氮(氧)化物荧光转换材料的发展趋势和在白光LED中的应用前景.     

SPS烧结制备新型荧光玻璃材料

以实验室自制SiO2粉体和商用Ce∶YAG荧光粉为玻璃原料,采用放电等离子体烧结（SPS）技术,在1 200℃保温2 min烧结得到有望用于白光LED封装的Ce∶YAG荧光玻璃。用X射线衍射仪（XRD）、荧光光谱（PL）等方法对制备获得的荧光玻璃样品进行表征。结果显示,烧结并没有破坏Ce∶YAG荧光粉的晶体结构,且荧光玻璃主体相仍为玻璃体,该荧光玻璃在460nm具有强吸收峰,在此波长激发下发射出530 nm左右的黄光。研究结果表明,本实验制备的Ce∶YAG荧光玻璃是一种具有重要应用前景的LED封装用新型荧光材料。     

Fluorescence improvement of Ba1.3Ca0.7SiO4:Eu,Mn phosphors via Dy addition and their color-tunable properties

A series of novel single-phase white phosphors Ba_1.3Ca_0.69−x−ySiO₄:0.01Eu²⁺,xMn²⁺, yDy³⁺ were synthesized by the solid-state method. The excitation spectra of these phosphors exhibit a broad band in the range of 260–410 nm, which can meet the application requirements for near-UV LED chips (excited at 350–410 nm). The emission spectra consist of two broad bands positioned around 455 nm and 596 nm, which are assigned to 5d→4f transition of Eu²⁺, and ⁴T₁→⁶A₁ transition of Mn²⁺, respectively. The luminescence intensity of phosphors enhances obviously by doping Dy³⁺ ions, and the intensity of two bands reaches an optimum when Dy³⁺ amounts to 2 mol%. In addition, thermoluminescence investigation of phosphor was conducted, getting two shallow trap defects with activation energy of 0.43 eV and 0.45 eV, which demonstrates the energy transfer mechanism of Dy–Eu through the process of hole and electron traps. By precisely tuning the Mn²⁺ content, an optimized white light with color rendering index (CRI) of R_a=84.3%, correlated color temperature (CCT) of T_c=8416 K and CIE chromaticity coordinates of (0.2941, 0.2937) is generated. The phosphor could be a potential white phosphors for near-UV light emitting diodes.     

白光发光二极管用荧光粉的研究进展

白光LED被称作第四代照明光源,有着庞大的市场。文章主要介绍了白光LED用荧光粉,特别是紫外/近紫外光激发的白光LED用荧光粉的技术现状,并指出今后的发展需要解决的问题。