Ca2SnO4:Eu3+的固相反应形成机理及发光性质研究

利用高温固相反应法合成了Ca2-xEuxSnO4发光粉末样品，采用X射线衍射技术和荧光光谱等测试手段对样品的固相反应形成机理及光谱特性进行了研究．对于CaCO3和SNO2（2：1）混合粉料，在1250℃进行固相反应时将优先反应生成不稳定的中间相CaSnO3，该相再与CaO继续反应生成最后稳定的目标相Ca2SnO4．Ca2-xEuxSnO4样品在240-360nm范围内存在着Eu^3＋-O^2-电荷迁移吸收带，随着Eu^3＋掺杂浓度（x=0．01-0．15）的增加，吸收带峰位从274nm红移至292nm附近．Ca2SnO4：Eu^3＋发光体的发射以电偶极跃迁^2Do-^7F2为主导地位，在紫外光激发下产生强的红光发射．在Ca2SnO4基质中，Eu^3＋离子的多声子弛豫过程几率小，当Eu^3＋掺杂浓度较低时，可以观察到来自于Eu^3＋较高激发态能级^5D2和^5D1上的辐射跃迁．Eu^3＋离子在同构的Ca2SnO4和Sr2CeO4基质中的发射光谱形状类似，但Ca2SnO4：Eu^3＋的红光发射强度远大于Sr2CeO4：Eu^3＋．     

红色蓄光材料Y2O2S:Eu3+的硫熔法制备及其发光性能

用硫熔法制备了系列红色蓄光材料Y2O2S ：Eux^3＋（0．01≤x≤0．10）的多晶粉末样品并系统研究了其发光特性。XRD结果表明,晶胞参数c随着Eu^3＋含量的逐渐增大而增大,而晶胞参数α没有明显的线性变化关系,这与Y2O2S ：Eu^3＋的晶体结构有关。Y2O2S ：Eux^3＋（0．01≤x≤0．10）的激发光谱相似,在626nm发射光监控下最大激发波长约在330nm附近。在330nm激发下,随着Eu^3＋含量逐渐增大,发射光谱最强发射峰位置从540nm右移至626nm,观察到红色特征发射峰626nm的强度逐渐增大,在Eu^3＋含量为0．09时,其强度达到最大。在最佳合成条件及最佳Eu^3＋含量下,正在进行掺杂Mg^2＋和Ti^4＋及其发光特性的研究。     

20GaF3-15InF3-20CdF2-15ZnF2-18PbF2-10SnF2-2TmF3玻璃光谱性质研究

制备了掺Tm^3 离子GICZPS玻璃：20GaF3-15InF3-20CdF2-15ZnF2-18PbF2-10SnF2-2TmF3，用Judd-Ofelt理论计算了玻璃的光学参数，研究了玻璃的发光性质，并探讨了其发光机理．结果表明，在641nm激发下，可以观察到485nm(^1G4→^3H6)和528nm(^1G2→^3H5)两个上转换荧光发射峰。     

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。     

Eu^2＋，Dy^3＋掺杂铝酸锶长余辉发光材料的研究

用固相法制备出了Eu^2＋，Dy^3＋共掺杂Sr4Al7O25：Eu^2＋，Dy^3＋、SrAl2O4：Eu^2＋，Dy^3＋长余辉发光材料。研究了硼酸含量对其制备过程及发光性能的影响。用XRD对所合成材料进行物相分析，用荧光光谱仪记录其发射光谱，并在暗室里拍摄紫外激发下的发光照片。结果表明：随着硼酸加入量的不同，Eu^2＋、Dy^3＋共掺杂铝酸锶的发光效果、形貌特征均不同。在某一范围内，随着硼酸添加量的增加，材料的发光性能、发光亮度均有所提高，烧结温度有所降低。     

976nm激发下Gd2O3：Ho3＋-Yb3＋纳米晶的绿红上转换发光

[摘要]本文用化学共沉淀法制备了Ho3＋离子和Yb3＋离子共掺杂的Gd20,纳米晶。研究了样品的上转换发光,不同煅烧温度、不同掺杂浓度对纳米晶发光性能的影响。样品的xRD图和sEM表明Gd2O3：Ho3＋-Yb3＋纳米晶是完整的立方相,属于纳米级。在976nrn激发下,观察到了绿红色上转换发光,发射出属于H03＋离子5S2—5I8跃迁的548．6nrn的绿光、对应于H矿离子下5F5-5I8跃迁的664nm的近红外光和属于Ho3＋离子5S2-5I17跃迁的756m的近红外光。观察到了不同Ho3＋离子浓度掺杂的纳米粉体的浓度猝灭现象。发射强度与激发功率的关系表明上转换发光是双光子过程,能量传递是主要的上转换机制,Yb起到了很好的敏化作用。     

掺Er3+硅酸盐玻璃上转换发光特性研究

研究了掺Er^3＋硅酸盐玻璃的吸收光谱和上转换光谱，应用Judd-Ofelt理论计算了Er^3＋强度参数Ωλ（λ=2、4、6）、跃迁振子强度、自发辐射几率、荧光分支比．上转换光谱分析表明：在522、545、658nm处有较强的绿光和红光，分别对应于^2H11／2→^4I15／2、^4S3／2→^4I15／2、^4F9／2→^4I15／2的跃迁，发光曲线拟合斜率分别为1．67，1．94，1．76；上转换发光机制主要是激发态吸收和能量转换，且均为双光子吸收过程．     

蓝色发光材料MGa_2S_4:Ce(M=Ca,Sr)发光特性的研究

制备了可用于蓝色TFEL的粉末发光材料MGa2S4：Ce（M=Ca，Sr）并对其晶体结构进行了X射线分析，测量并研究了其激发光谱和发射光谱，研究了Ce3 浓度的变化对CaGa2S4：Ce和SrGa2S4：Ce的激发光谱.发射光谱、色纯度及发光强度的影响，同时研究了基质组份的改变对发光特性的影响．结果表明，CaGa2S4：Ce和SrGa2S4：Ce可发射纯蓝色光，色纯度好．对CaGa2S4：Ce来说，实现其高效率的、纯蓝色发射的最佳Ce3 浓度为6mol％，而SrGa2S4：Ce的最佳Ce3 浓度为3～4mol％．     

Luminescent properties of KNaCa2（PO4）2：Dy3＋ phosphor for white LED

采用高温固相法制备了KNaCa2（PO4）2：Dy3＋发光材料并对其发光特性进行了研究。光谱显示,KNaCa2（PO4）2：Dy3＋激发谱为300～500nm范围内的一系列锐谱,可被InGaN管芯和蓝光有效激发。尤其在385nm紫外光激发下,样品呈现较强白光发射,主发射峰位于485和577nm,对应Dy3＋的。F9/2-6H15／2、4F9/2-6H13/2跃迁,形成“黄＋蓝”单一基质白光。研究了Dy3＋掺杂浓度对KNaCa2（PO4）2：Dy3＋发光性能的影响,随Dy3＋浓度增加,发光强度先增大后减小,最佳掺杂浓度为0．04mol,Y／B值在较小范围内先增大后减小。根据Dexter理论分析其浓度猝灭机理为电偶极一电偶极相互作用。测量并标定了Dy抖不同浓度下样品的色坐标均呈现白光发射。研究表明,KNaCa2（PO4）2：Dy3＋材料是一种适合紫外-近紫外-蓝光激发的单一基质白光荧光粉。     

纳米包覆法制备SrAl2O4：Eu^2＋，Dy^3＋发光粉及铁杂质猝灭研究

利用纳米包覆技术制备了掺杂不同含铁量的发光粉SrAl2O4：Eu^2＋，Dy^3＋通过透射电子显微镜（TEM）研究了纳米氧化铝水合粒子的包覆过程。通过X射线衍射（XRD）、光谱测量等分析手段研究了铁杂质对发光粉}生能方面的影响。结果表明，微量铁的引入没有使发光粉的晶相结构发生变化，但却大大降低了其发光强度。随着铁含量从0．001mol增加到0．01mol，余辉平均发光强度下降了50％，这种变化可能是由于Fe^3＋-O^2-知中心将一部分能量传递到红外区域引起的，同时首次发现了铁在铝酸锶晶体中的红外发光现象。     

微波场作用下球形亚超细 CaS:Mn2+，Eu2+的快速合成

在微波场作用下,首次快速合成了球形亚超细尺寸的CaS: Mn2+,Eu2+ 深红色荧光体,SEM 照片显示其粒径为250 400nm,并可观察到纳米粒子的团聚现象,呈现零维纳米材料的特性. 实验结果证实,Mn2+与Eu2+离子间存在着能量传递过程,因而Mn2+对Eu2+的发光具有明显的敏化和增强作用.     

微波场作用下球形亚超细CaS:Mn2+,Eu2+的快速合成

在微波场作用下,首次快速合成了球形亚超细尺寸的ＣａＳ：Ｍｎ＾２＋,Ｅｕ＾２＋深红色荧光体,ＳＥＭ照片显示其粒径为２５０－４００ｎｍ,并可观察到纳米粒的团聚现象,呈现零维纳米材料的特性,实验结果证实,Ｍｎ＾２＋与Ｅｕ＾２＋离子间存在着能量传递过程,因而Ｍｎ＾２＋对Ｅｎ＾２＋的发光具有明显的敏化和增强作用。     

Gd2O3:Eu phosphor powders prepared using a size-controllable droplet generator

Gd₂O₃:Eu phosphor powders were prepared by a filter expansion aerosol generator (FEAG) process capable of changing the mean size of droplets. The change in the mean size of the Gd₂O₃:Eu phosphor powders according to the concentrations of polyethylene glycol added to spray solutions was caused by the difference in the mean size of the droplets produced via the FEAG process. The mean sizes of droplets produced by the FEAG process were affected by the surface tension and viscosity of the spray solutions. The mean sizes of the Gd₂O₃:Eu phosphor powders obtained from the spray solutions with the same concentration of metal salts changed from 1.5 to 4.2 μm according to the concentrations of polyethylene glycol and citric acid added to the spray solutions. The maximum photoluminescent intensity of the phosphor powders obtained from the spray solutions with polymeric precursors and boric acid flux was 144% of that of the phosphor powders obtained from the aqueous spray solutions without flux.     

Improvement of morphology and luminescence of CaS:Eu<Superscript>2+</Superscript> red-emitting phosphor particles via carbon-containing additive strategy

CaS:Eu²⁺ red-emitting phosphors particles, were prepared by the precipitation method, followed by sintering in the atmosphere over the mixture of sulfur powder, Na₂CO₃, and carbon-containing compounds such as tartaric acid, citric avid, glucose, and cane sugar. The structure, morphology and photoluminescence performance of the as-prepared samples were investigated by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence spectrum (PL), respectively. The influences of carbon-containing additives on its crystallization behavior, morphology, and enhancement in luminescence of CaS:Eu²⁺ particles were studied. CaS:Eu²⁺ particles without additive show inhomogeneous, rough and aggregation with the size of 75–125 nm, but the spherical particles with mean size of about 110 nm were obtained by adding carbon-containing compounds. Compared with phosphor without additive, the addition of carbon-containing materials induced a remarkable increase of PL, in the order of cane sugar, glucose, citric acid, and tartaric acid. This enhancement is duo to the improvement of crystallinity, particle morphology and size distribution of the samples by adding carbon-containing additive.     

微波合成条件下Sm3+对CaS:Eu2+红色发光的增强

首次在微波场作用 下快速合成了类球形亚超细CaS:Sm^3 ,Eu^2 磷光体,平均粒径为240~450nm,系统考察了Sm^3 ,Eu^2 双掺离子在没掺杂浓度时对CaS磷光体荧光性质的影响,并探讨了Sm^3 →Eu^2 之间的能量传递机理。     

SrAl2O4:Eu2+发光材料的合成工艺研究

以碳粉作还原剂,SrCO3、Al2O3、Eu2O3为原料,在还原气氛下采用固相烧结法合成了SrAl2O4:Eu2+发光材料;对合成物进行了X射线粉晶衍射、荧光光谱测定;并初步探讨了Eu2+的含量、制备工艺过程中的焙烧温度、保温时间、冷却方式等因素对合成样品发光性能的影响.     

Formation of Photosensitive Films by High Temperature Sintering

Photosensitive ZnCdS:CdS structure was formed by screen printing of ZnS and CdCl2 powders followed by sintering at high temperatures. The sintering of the film at high temperatures resulted in the formation of ZnCdS (ZCS) nanoparticles in a CdS matrix by an ion interchange reaction followed by a solid state reaction. It was observed that the film composition depends on the sintering atmosphere (air in the present case). The photosensitivity of the film depends on parameters such as film composition, sintering atmosphere and sintering temperature. Influence of these parameters on the dark and photocurrent characteristics of ZCS:CdS structure is explained by taking into consideration the presence of deep acceptor centers related to Cd and Zn vacancies and shallow donor levels due to S vacancies in the films.     

Effect of zinc metal addition on microstructural evolution of Zn0.22Cd0.78S$ phosphors studied by transmission electron microscopy

The effect of zinc powder addition on the microstructural evolution of fine Zn_0.22Cd_0.78S:Ag$, Cl phosphor particles was investigated in relation to the luminescent property of phosphors. The phosphor microstructures were analyzed by high-resolution transmission electron microscopy (HRTEM) using the ultramicrotome technique for specimen preparation. The phosphor baking process at 480 °C for 30 min in air results in significant damage to the surface structure of the phosphors due to the decomposition and oxidation of the phosphor itself. The addition of zinc metal powders into the Zn_0.22Cd_0.78S$ phosphors suppresses the oxidization and decomposition of phosphors by oxidizing zinc metal during the baking process in air. The oxidation of the zinc powders during baking provides the baking furnace with less oxidizing atmosphere for phosphor particles. The structure of phosphors, especially at the surface region, is much less degraded compared to the phosphors baked with no zinc metal addition. © 2000 Kluwer Academic Publishers     

Methods to improve the fluorescence intensity of CaS:Eu red-emitting phosphor for white LED

In order to improve the fluorescence intensity of red-emitting phosphor based on alkaline earth sulfide CaS:Eu²⁺ for white LED (light-emitting diode), many methods were used. When the flux is NH₄F, auxiliary activator is Er³⁺, intensity of phosphor CaS:Eu²⁺ has the strongest brightness. On the other hand, introduction of Sr could make the maximum excitation band shift to high energy, which make the phosphor match well with blue light GaN-based LED; Mg partly substitute for the alkaline earth Ca could make the intensity of red emitting phosphor increase greatly.     

Synthesis and photoluminescence of nano-sized (Gd,Y)PO4:Eu3+ by solution combustion method

We synthesized (Gd(1-x)Yx)(0.94)PO4:Eu(0.06) (0 < or = x < or = 1.0) phosphor powders of an ultra-fine size (approximately 23 nm), smooth surface, and spherical and regular morphologies by the solution combustion method. The crystallite sizes of the annealed (Gd(1-x)Yx)(0.94)PO4:Eu(0.06) phosphors with x = 0, 0.25, 0.5, 0.75, and 1.0 were 63.3, 62.3, 49.9, 45.1, and 43.3 nm, respectively. The photoluminescent characteristics of the phosphors were studied under vacuum ultraviolet excitation, depending on the Y3+ concentration. The intensity of the peaks corresponding to the red emission increased with increases in the Y3+ concentration. The Y(0.94)PO4:Eu(0.06) phosphor emitted the strongest intensity and the purest red color.