BaMgAl10O17:Eu2+蓝色荧光粉表面包覆MgF2的性能

采用机械研磨包覆法对BaMgAl10O17:Eu2 (BAM)粉体进行表面包膜处理,获得了表面均匀包覆MgF2膜层的BAM荧光粉。并用SEM、XRD和IR手段对其表面形貌、晶格结构性能进行了表征;用EDS对BAM粉体的表面元素进行了定性分析;用荧光光谱测试对荧光粉的发光性能进行了研究。结果表明,在BAM粉体表面均匀包覆MgF2层后,BAM的晶格结构、发光性能没有改变,初始亮度较未包覆的荧光粉有所降低,经过相同条件的热处理后,包覆MgF2荧光粉的亮度热衰减程度明显低于未包覆的荧光粉,且没有发生明显的色坐标偏移现象。     

银颗粒包覆CaTiO3∶Eu3+荧光粉的制备及其光学性能的研究

本文利用非均匀成核结晶的原理,在CaTiO3∶Eu3+荧光粉表面包覆银颗粒.利用场发射扫描电镜(FE-SEM)和荧光光谱分析仪(PL),对包覆有银颗粒荧光粉的形貌和性能进行了表征.FE-SEM图显示该方法可成功将银颗粒包覆到荧光粉表面,通过调节反应温度,氨水滴加速度和AgNO3溶液浓度,可改变包覆形貌.当荧光粉表面均匀包覆着银颗粒时,由于银颗粒的局部表面等离子体激元共振(localized surface plasmon resonance,简称LSPR),荧光粉发光效率较高.     

近红外上转换发光材料的稳定性

利用吸附层媒介机制,采用正硅酸四乙酯（TEOS）包覆近红外上转换材料CaS：Eu,Sm,在其表面生成了一层致密的SiO2膜,可使其发光性能在潮湿空气中不衰减．通过X射线衍射仪（XRD）、扫描电镜（SEM）、能谱仪（EDS）比较经TEOS包覆改性前后的CaS：Eu,Sm的组分和形貌．同时,用荧光光谱仪测定了包覆前后荧光粉发光性能的变化情况以及在空气中的稳定性．结果表明：先用无水乙醇洗涤试样,再加入TEOS用超声波分散的方法可以在CaS：Eu,Sm荧光粉颗粒的表面包覆一层SiO2膜,能显著地提高荧光粉的化学及发光稳定性．     

荧光粉表面包覆研究概况

荧光粉的表面包覆可以改善粉体团聚、润湿、烧结以及耐温、耐化学腐蚀等诸多性能。本文介绍了荧光粉表面包膜体系和包覆技术,并对荧光粉的包覆前景进行了展望。     

Y3Al5O12∶Eu3+荧光粉表面包覆SiO2的研究

采用化学均相沉淀法在YAG∶Eu3+荧光粉表面包覆了SiO2.利用XRD、SEM、Zeta电位分析、傅里叶红外光谱和荧光光谱等手段对包覆处理前后的样品进行了测试和表征.结果表明:SiO2包覆层紧密附着在荧光粉表面,而不改变YAG∶Eu3+荧光粉的晶体结构和发光中心;并通过改善荧光粉的表面状态,在一定程度上提高了荧光粉的发光强度.     

白光发光二极管用单体白色荧光粉的研究进展

近年来,单体白色荧光粉,尤其是基于能量传递原理构建的白色荧光粉成为发光领域的研究热点。简要评述了近5年紫外一近紫外基白光LEDs用单体白色荧光粉的研究进展。重点阐述了单掺杂体系,以及基于能量传递原理构建的双掺杂及三掺杂等单体白色荧光粉的研究结果与最新进展;同时,分析和预测了该类材料的研究前景及发展方向。     

碱土铝酸盐蓄光型发光材料的后处理研究

采用胶体包覆和表面成膜包覆相结合的方法,对碱土铝酸盐蓄光型发光材料进行包覆后处理研究。分析了包覆后处理对材料表面结构变化、发光性能及应用性能的影响。研究表明:经过包覆后处理的发光材料在水中浸泡时,发光材料对水能保持稳定,水相的pH值和电导率保持基本稳定;而未经包覆后处理的发光材料在水中分解,其水相的pH值和电导率上升很快。经过包覆处理的SrAl_2O_4:Eu,Re(Re为稀土元素)(PLO)在水中浸泡720 h后能保持80％的初始亮度,未经处理的发光材料则失去发光性能。包覆后处理能在发光材料表面形成了一层连续的比较致密的保护层,有效地减少外界对发光材料的影响,而且可以修复发光材料颗粒原有的裂纹等缺陷。包覆处理后能有效提高发光材料的应用性能,如耐水性、分散性及耐高温性能,更能适应不同的应用领域。     

Sr2MgSi2O7∶Eu2+,Dy3+荧光粉包覆改性后的热稳定性能研究

以Al(NO3)3作为包覆材料,通过直接沉淀法在Sr2MgSi2O7∶Eu2+,Dy3+荧光粉表面包覆了一层勃姆石(γ-AlOOH).采用XRD、SEM、TEM、TG-DSC和瞬态/稳态荧光光谱仪对未包覆的荧光粉和包覆后的荧光粉进行了测试表征.结果 表明,γ-AlOOH包覆膜均匀地沉积在荧光粉的表面,且其厚度约为40 nm.γ-AlOOH在高温热处理过程中会转变成Al2O3.当热处理温度≥1000℃时,Al2O3与Sr2MgSi2O7基质发生固相置换反应并生成了SrAl2Si2O8,MgO和SrO,包覆后的荧光粉新出现了一个峰值为384 nm的紫外发射带.当热处理温度为900℃、1000℃、1150℃和1200 ℃时,包覆后的荧光粉的蓝光发光强度比包覆前的荧光粉更强,而在1050℃和1100℃时反而更弱,这与Al2O3晶体的F色心缺陷有关.     

发光二极管用荧光粉Sr2-xBaxSiO4:Eu的制备、发光性能及应用

采用高温固相法制备了发光二极管(light-emitting diode,LED)用硅酸盐荧光粉Sr2-xBaxSiO4:Eu.用热重-差热分析、X射线衍射和扫描电镜对荧光粉进行了表征,讨论了碱土元素锶钡的含量对激发光谱与发射光谱的影响.结果表明:在还原气氛下,1 245 ℃反应3 h能得到发光性能较好的荧光粉;荧光粉中锶钡的含量对其发射光谱及激发光谱有较大影响,随着荧光粉中钡含量的增加,发射峰及激发峰位置逐渐蓝移,强度也逐渐增强;并用晶体场强及共价性对其进行了讨论.该荧光粉颜色可调,可用于紫外、近紫外、蓝色LED的封装.     

白光LED照明用新型荧光粉的制备和性能研究

首次报道利用高温固相法结合超声波分散技术合成了Sr3-xMgSi2O8:xEu2 高亮度白色荧光粉,并对其发光性能进行了研究。该荧光粉在近紫外光激发下发出较强的白光,发射光谱由两个主峰组成,分别位于468.4nm和546.0nm处,并具有不同的荧光寿命,归结为处于不同格位上的Eu2 离子的5d-4f电子的跃迁发射,从而在单一基质中混合得到了白光,这两个发射峰所对应的激发光谱均分布在250nm-450nm的紫外区,该荧光粉可以被具有400nm的近紫外光发射的InGaN管芯产生的紫外辐射有效激发而产生白光,是一种性能良好的很有前途的单一基质白光LED照明用稀土荧光粉。     

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.     

适用于催化剂和发光材料研究的并行合成和高通量表征技术

介绍了作者课题组近年来所发展的适用于催化材料和发光材料研究的并行合成和高通量表征技术,以及在新材料筛选方面开展的工作。在并行合成方面包括组合喷射合成仪、微型阵列式溶液燃烧技术以及结合四元掩模和连续掩模的磁控溅射和脉冲激光沉积系统;高通量表征部分包括真空紫外荧光照相系统和组合光谱扫描仪、红外热成像筛选装置和同步辐射红外光谱成像系统。最后,简要介绍了利用所发展的组合技术在稀土聚合物敏化发光材料、真空紫外荧光材料以及可见光响应光催化材料方面开展的工作。     

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.     

ZnO:Al包覆CaSiO3:(Pb,Mn)荧光粉

利用溶液中的共沉淀反应制备了CaSiO3:(Pb,Mn)红色光致荧光粉.以Zn(NO3)2·6H2O和AlCl3·6H2O为原料,借助CO(NH2)2水解反应,用化学均相共沉淀法和热处理工艺在荧光粉表面包覆一层ZnO:Al透明导电薄膜.对包覆前后的样品进行了X射线衍射结构分析、光致荧光分析、透射电镜形貌观察及电阻测量.结果显示:包覆后荧光粉的电导率显著提高,但光致荧光峰的位置和强度无明显变化.综合考虑包覆对荧光粉电阻率和荧光性质的影响,优化包覆条件和热处理条件为:n(Zn)/n(Ca)=10%,n(Al)/n(Zn)=5%,75℃水解1 5 h;包覆后的样品在500℃热处理45 min.     

助熔剂对YAG:Ce3+荧光粉性能的影响

采用微波均相沉淀方法,添加NaF、BaF2及其与H3BO3的混合助熔剂制备YAG:Ce3+荧光粉。同纯YAG:Ce3+荧光粉相比,其结晶度高,衍射峰无杂峰,且有明显团聚性;发光强度更高,加入NaF的添加量为6%最佳。加入BaF2的YAG:Ce3+荧光粉与纯YAG:Ce3+荧光粉相比,其发光强度较高。加入混合助熔剂(1%BaF2+1%H3BO3)的荧光粉的发光强度最大。     

燃烧法合成掺铕硼酸镧钙荧光粉及其发光性能研究

采用燃烧法合成Eu：La2CaB10O19荧光体,用XRD、SEM并研究了所得荧光粉的形态、粒度和物相,用荧光分光光度计测定了荧光粉的发光性能并与高温固相法制备的粉体对比。结果表明Eu：La2CaB10O19荧光体的晶体结构属于单斜晶系结构。燃烧后所得的前驱体样品在800℃下烧结1.5 h便具有很好的晶相,制备产物粒度在300 nm左右,在395 nm激发下的发射强度跟高温固相法制备的Eu：La2CaB10O19强度接近。     

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。     

Dy and Eu activated Ca3B2O6 phosphors for near ultraviolet‐based light‐emitting diodes

The Dy‐ and Eu‐activated Ca₃B₂O₆ phosphors were synthesized by a high‐temperature solid‐state reaction technique and their structural and luminescent properties were investigated. The phosphors are characterized by X‐ray diffraction, photoluminescence spectra, and Commission International de I'Eclairage (CIE) chromaticity coordinates. It is found that the charge compensator Na⁺ plays an important role in modifying the emission spectral profiles of Dy and Eu ions in the phosphors. The ratio of the emission located at the yellow wavelength portion to that located at the blue wavelength region of the Dy³⁺ ions can be apparently tuned by changing the Na⁺ content. The luminescence intensity of the phosphors can be enhanced with introducing Na⁺ ions as well. The emission colors of Dy/Eu codoped phosphors change from blue to white and successfully acquire the superior white light emission (x = 0.330, y = 0.329) by appropriately tuning the Na⁺/Dy³⁺ content and the excitation wavelength. The energy transfer process from Eu²⁺ to Dy³⁺ and Eu³⁺ occurs in the Dy/Eu codoped phosphors, providing a further approach to modify the emission spectral profile of the examined phosphors. The phosphors presented here have promising applications in the fields of light‐emitting diodes.     

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.