NaYF4:Yb,Er材料的制备及其上转换发光性能

通过沉淀法制备Yb3+和Er3+共掺的NaYF4上转换发光材料,考察了主要制备工艺条件对材料上转换发光性能的影响,并探讨了其上转换发光的机理。利用x射线衍射(XRD)、透射电镜(TEM)、荧光光谱仪对样品进行了表征。结果表明,Yb3+和Er3+的掺杂浓度分别15%(摩尔分数,下同)、3%,焙烧温度为600℃时可得到发光性能较好的六方相NaYF4:Yb,Er上转换材料,其主要上转换途径是Yb3+和Er3+之间的能量转移,且Er3+的红、绿光发射均为双光子过程。     

水溶性NaYF4：Yb，Er上转换发光纳米粒子的可控合成与发光性能研究

采用溶剂热法合成出尺寸小于30 nm的NaYF4：Yb, Er上转换纳米晶,用柠檬酸（CA）做表面活性剂使得产物具有良好的水溶性。实验探索得出NaOH或者CA的加入量能够调节溶液中能与稀土离子络合的有效配位基团-COO-的浓度,进而影响NaYF4从立方相到六方相的相变过程、实现产物形貌的控制和上转换发光性能的调变。逐渐提高NaOH的加入量,产物从30 nm的α-NaYF4：Yb, Er纳米粒子转变为尺寸300 nm 的β-NaYF4：Yb, Er 微球。提高CA 的加入量同样会促进β-NaYF4：Yb, Er微球的形成。还研究上述不同合成条件下,不同形貌结构的产物的上转换发光性能。     

Effect of glass network modifier R2O (R=Li,Na and K) on upconversion luminescence in Er3+/Yb3+ co-doped NaYF4 oxyfluoride glass-ceramics

The effect of glass network modifier R2O (R=Li, Na, K) on upconversion luminescence in Er3+/Yb3+ co-doped NaYF4 oxyfluoride glass-ceramics was investigated. NaYF4 nanocrystals with different sizes were...     

Yb3+，Er3+掺杂Y2Ti2O7荧光粉的制备与上转换发光机理研究

采用溶胶-凝胶法制备合成了(Y_0.98-xYb_xEr_0.02)₂Ti₂O₇(x=0, 0.02, 0.04...0.10)荧光粉, 分别采用XRD和荧光光谱仪对样品的结构和上转换发光性能进行了表征.研究了Yb3+掺杂浓度对样品上转换发光性能的影响, 并对样品的发光机理进行了研究.结果表明, 所得样品为面心立方结构的烧绿石相.在980nm激发下, 样品展现出很强的上转换荧光发射并且发光颜色可以通过Yb3+掺杂浓度来调节.样品上转换绿光和红光发射均为双光子过程并且交叉弛豫过程在上转换红光发射过程中占据主导作用.      

Preparation and characterization of upconversion nanocomposite for β-NaYF_4:Yb~(3+),Er~(3+)-supported TiO_2 nanobelts

Hexagonal NaYF4:Yb3+,Er3+ (β-NaYF4:Yb3+,Er3+) nanoparticles supported on TiO2 nanobelts were prepared using two-step pro- cedures of ion-exchangeable process and hydrothermal treatment: layered titanate nanobelts were first ion-exchanged with Y3+, Yb3+ and Er3+ cations to produce titanate nanobelts with these cations, and then, the product nanobelts in NaY solution were treated under hydrothermal con- dition to transform into anatase TiO2 nanobelts supported with β-NaYF4:Yb3+,Er3+ nanoparticles. The final products were characterized by various measurement techniques. Many preparation conditions, e.g., the content of added precursors, reaction time and pH value, were optimized to obtain nanocomposites including relatively uniform nanoparticles with strong upconversion (UC) emission intensity. The measurement results showed that the anatase TiO2 nanobelts, supported by the large number of β-NaYF4:Yb3+,Er3+ nanoparticles with 30–70 diameter range and very strong UC emission, could be achieved under suitable preparation condition. The UC emission intensity of the nanoparticles with the concentrations of Yb3+ and Er3+ closer to 20 mol.% and 1 mol.% was the strongest.     

Mn~(2+),Yb~(3+)共掺硼硅酸锌玻璃的长余辉性能与陷阱分布的研究

采用高温熔融法制备了Mn2+,Yb3+共掺的硼硅酸锌长余辉玻璃。通过荧光发射光谱、余辉发射光谱、余辉衰减曲线及热释光谱对材料的发光性能、结构、陷阱分布进行了表征,重点通过余辉衰减曲线和热释光谱分析了Yb3+掺杂浓度的变化对材料余辉性能和陷阱分布的影响,结果发现:ZBSMY玻璃的余辉发射源自于Mn2+的4T1(4G)→6A1g(6S)跃迁;共掺离子Yb3+按0.1%(摩尔分数)掺杂时,余辉性能最佳,陷阱的拟合深度分别0.79和1.04 eV,且浅陷阱浓度达到最大。     

柠檬酸的用量在溶胶凝胶燃烧合成法中对Y_2O_3:Er发光性能的影响

采用硝酸盐-柠檬酸溶胶凝胶燃烧合成法制备了Er3+掺杂Y2O3上转换发光粉体,研究了不同柠檬酸用量对Y2O3:Er粉体晶体结构、颗粒形貌、颗粒尺寸和上转换发光性能的影响。研究结果表明,柠檬酸加入量的多少不会影响粉体的晶体结构,XRD图谱的衍射峰位置没有发生改变;只是随着柠檬酸的增加,可能会导致晶粒发育不完全,使得参加衍射的晶胞数变少,衍射峰发生明显的宽化。不同柠檬酸加入量下得到的粉体,颗粒尺寸都在纳米级;随着柠檬酸加入量的增加,颗粒尺寸变小,表面能增加,团聚更明显。柠檬酸加入量对发光性能影响较为明显,当柠檬酸与硝酸盐的摩尔比为2时,4S3/2/2H11/2→4I15/2跃迁所对应的绿光发射强度和4F9/2→4I15/2跃迁所对应的红光发射强度都呈现出了最大值。这是因为体猝灭中心与表面猝灭中心对Er3+离子的上转换发光猝灭作用都处于一个相对较弱的状态,同时由于C3 i格位上的Er3+离子的电偶极跃迁的宇称禁戒解除,使得C3 i格位上的Er3+离子的发射增强,这就使得粉体的上转换发光整体增强,并达到最大值。     

超长余辉发光材料的研究

综述了碱土铝酸盐 MAl2 O4 ∶ Eu2 、RE3 (M=Mg,Ca,Sr,Ba;RE=Y,L a,Ce,Pr,Nd,Sm,Gd,Tb,Dy,Ho,Er,Tm,Yb)的超长余辉发光性质。探讨了发光材料的基质组成、结构和形态对发光性能的影响 ,激活剂的种类、性质及其对稀土离子的超长余辉发光性能的影响。最后研讨了发光机理的两种模型     

SiO_2包覆稀土上转换纳米晶的可控合成及发光性能研究

采用溶剂热法合成了粒径在20 nm~30 nm的形貌均一的球形NaYF_4∶Yb,Er纳米晶。通过调节不同配比,合成了SiO_2层厚度为8 nm及10 nm的具有良好水溶性的UCNs@SiO_2纳米材料。考察了不同配方比对SiO_2层包裹厚度及发光性能的影响。利用透射电镜(TEM)、X射线衍射(XRD)、荧光光谱仪等对样品进行了表征,结果表明该材料核-壳结构明显、形貌均一、结构稳定,在980 nm的激发下保持了良好上转换发光特性。     

水热法制备ZnO∶Eu,Yb,Li发光粉及其上转换发光特性

采用低温水热法合成了Eu~(3+),Yb~(3+)和Li~+共掺杂ZnO上转换荧光粉。采用X射线衍射仪(XRD)和扫描电镜(SEM)对样品进行了表征。研究了Yb~(3+)掺杂摩尔比、退火温度对样品上转换发光强度的影响。结果表明,所制备的ZnO∶Eu,Yb粉体为六方纤锌矿结构的六角柱微米棒。在980 nm激光(LD)激发下,在542 nm和660 nm处出现发射峰,讨论了其上转换发光机理。退火温度为650℃时, ZnO∶1.5%Eu,8%Yb,10%Li的红色上转换发光及ZnO∶1.5%Eu,10%Yb,10%Li的绿色上转换发光均达到最强。     

Up-conversion processes of rare earth ions in heavy metal glasses

Heavy metal lead germanate glasses doubly doped with Yb3+ and Ln3+ ions(Ln=Er,Tm) were investigated.Up-conversion spectra of Er3+ and Tm3+ were registered under diode-laser excitation of Yb3+.Up-conversion luminescence bands corresponded to 4S3/2→4I15/2(green) and 4F9/2→4I15/2(red) transitions of Er3+ as well as 1G4→3H6(blue) and 3H4→3H6(NIR) transitions of Tm3+,respectively.     

Phase-, shape- and size-controlled synthesis of NaYF4：Yb3＋,Er3＋ nanoparticles using rare-earth acetate precursors

Hexagonal-phase NaYF4：Yb3＋,Er3＋ upconversion nanoparticles（UCNPs） with a uniform size distribution were synthesized using rare-earth acetates as precursors. The effects of reaction temperature and time on the phase transition process of the UCNPs were systematically studied. Based on the evolution of particle morphology and phase with temperature and time, it could be concluded that the transition from cubic phase to hexagonal phase for NaYF4：Yb3＋,Er3＋ UCNPs was consistent with a dissolution/recrystallization process. In addition, the shape and size of the UCNPs could be controlled by adjusting the solvent ratio and the precursor ratio, respectively.     

稀土硼氢化合物对环氧环己烷的开环聚合

合成了三类稀土硼氢化合物Ln(BH4)3(THF)3[Ln=Er(1),Yb(2)]、[(Me3Si)2NC(NCy)2]Ln(BH4)2(THF)2[Cy=C6H11,Ln=Er(3),Yb(4)]和(ArO)Ln(BH4)2(THF)2[Ar=C6H2-2,4,6-t-Bu3,Ln=Er(5),Yb(6)],首次研究了它们催化环氧环己烷(CHO)开环聚合的性能.其活性顺序为5～6＞1～3＞2＞4,说明吸电性配体以及Lewis酸性较大的稀土元素对金属硼氢化物催化聚合活性是有利的.温度越高,催化剂催化活性越好.聚合物分子量在1万左右,分子量分布在2.2左右.     

Er0.5Yb1.5Si2O7 环境障涂层高温CMAS 熔盐腐蚀行为研究

硅基陶瓷材料以其优异的性能成为新一代航空发动机热端的候选材料,其在恶劣的服役环境中需要环境 障涂层 ( Environmental Barrier Coating, EBC ) 的保护。以稀土硅酸盐为面层的第三代EBC 是目前研究的热点之 一。采用大气等离子喷涂工艺制备了Er0.5Yb1.5Si2O7 环境障涂层面层样品,研究涂层在钙镁铝硅酸盐(CaO-MgOAl2O3- SiO2, CMAS) 覆盖浓度15 mg/cm2、保温温度1350 ℃、保温时间5 h 的腐蚀条件下的腐蚀行为。研究发现 Er0.5Yb1.5Si2O7 涂层与CMAS 反应后产物为磷灰石相Ca2(Er0.25Yb0.75)8(SiO4)6O2 与Er0.5Yb1.5Si2O7 相,涂层顶部残留 CMAS 熔盐,内部出现反应区和渗透区。     

Energy transfer processes from Yb3＋ to Ln3＋ （Ln=Er or Tm） in heavy metal glasses

Heavy metal glasses doubly doped with Yb3+ and Ln3+ ions(Ln=Er or Tm) were studied. Glass host matrices were limited to lead borate glass and lead germanate glass. Efficient resonant(Yb3+-Er3+) and non-resonant(Yb3+-Tm3+) energy transfer was observed for the studied systems. Near-infrared luminescence spectra at 1.53 μm(Er3+) and 1.9 μm(Tm3+) were detected under excitation of Yb3+ by 975 nm diode laser line. They corresponded to 4I13/2→4I15/2(Er3+) and 3F4→3H6(Tm3+) transitions of rare earth ions, respectively. The unusual large spectral linewidth nearly close to 110 nm for 4I13/2→4I15/2 transition of Er3+ ions in lead borate glass was obtained, whereas long-lived near-infrared luminescence at 1.53 μm was detected in lead germanate glass. Quite different situation was observed for Yb3+-Tm3+ doubly doped glasses. In contrast to lead borate glass, near-infrared(3F4→3H6) luminescence spectra were registered for Tm3+ ions in lead germanate glasses, only. These phenomena strongly depended on stretching vibrations of glass host, which was confirmed by FT-IR spectroscopy.     

Up-conversion luminescence of Er~（3＋）-doped and Yb~（3＋）/Er~（3＋） co-doped 12CaO·7Al_2O_3 poly-crystals

The optical properties of Er3+-doped and Yb3+/Er3+ co-doped 12CaO·7Al2O3 (C12A7) poly-crystals, synthesized by high temperature solid state method, were investigated in detail. For Er3+-doped and Yb3+/Er3+ co-doped C12A7 poly-crystals, two main emission bands centered around 530/550 nm (green) and 660 nm (red) were observed under 980 nm diode laser excitation via an up-conversion process. The intensity of green up-conversion emission had a strong increase in Er3+ (1.0 mol.%, 1.5 mol.%, 3.0 mol.%), and the intensity ratio of red to green up-conversion emission had an increase in Yb3+ (1.0 mol.%, 2.0 mol.%, 10. 0 mol.%)/Er3+ (fixed at 1.0 mol.%). This detailed study of the up-conversion processes allowed us to identify the dominant up-conversion mechanisms in Er3+-doped and Yb3+/Er3+ co-doped C12A7 poly-crystals.     

上转换发光晶体β-NaYF_4∶Yb~(3+),RE~(3+)的合成方法研究进展

稀土上转换发光晶体在近红外光的激发下能够发出可见光,化学组成为β-NaYF_4∶Yb~(3+),RE~(3+)(RE=Tm,Ho和Er)的晶体是发射绿色、蓝色和红色可见光的最佳材料。综述了用水热法、热分解法和有机溶剂热法合成稀土上转换发光晶体研究现状,系统阐述了各种方法有机试剂、前驱体摩尔比、掺杂Gd~(3+)、反应温度和时间等条件对β相上转换晶体形貌和粒度的影响,并对在生物医学领域应用的粒度10 nm的核壳型上转换发光晶体合成方法以及拓展其应用领域进行了展望。     

Luminescence properties of Tm^3＋/Yb^3＋, Er^3＋/Yb^3＋ and Ho^3＋/Yb^3＋ activated calcium tungstate

CaWO4 phosphor activated by the Tm3+/Yb3+,Er3+/Yb3+ and Ho3+/Yb3+ ions were synthesized by a traditional high-temperature solid-state method.The crystal structures and morphologies of the products were characterized by X-ray powders diffraction method(XRD) ,infrared spectra(FT-IR) and scanning electron microscopy(SEM) .The samples were found to show up-conversion luminescence properties.CaWO4 doped with Tm3+/Yb3+ showed blue luminescence characteristic of Tm(III) ion in the range of 460-485 nm,corresponding to the 1G4→3H6 electronic transition.CaWO4 doped with Er3+/Yb3+ showed strong green luminescence at 510-565 nm(2H11/2,4S3/2→4I15/2) and weak red luminescence at 640-685 nm(4F9/2→4I15/2) of Er(III) ion.CaWO4 doped with Ho3+/Yb3+ phosphor emitted green luminescence at 525-560 nm(5S2,5F4→5I8) and red luminescence at 630-670 nm(5F5→5I8) and at 730-770 nm(5S2,5F4→5I7) ,which is the characteristic of Ho(III) ion.     

Upconversion luminescence of Yb3+/Ho3+/Er3+/Tm3+ co-doped KGd(WO4)2 powders

Different lanthanide ions (Yb3+/Ho3+/Er3+/Tm3+) codoped KGd(WO4)2 phosphors were prepared by high-temperature solid-state reaction. The upconversion luminescence properties of two-ion and three-ion co-doped KGd(WO4)2 phosphors were investigated in detail. The concentration quenching effect of the two-ion co-doped KGd(WO4)2 phosphors was studied, and the optimum concentration of Ho3+, Er3+ and Tm3+ are 2 mol.%, 2 mol.% and 3 mol.%, respectively. The Yb3+/Ho3+/Tm3+ co-doped KGd(WO4)2 sample is the best white ...     

A novel synthesis method and up-conversion properties of hexagonal-phase NaYF4:Er nano-crystals

A novel synthesis method for hexagonal(β)-phase NaYF4:Er nano-crystals(NCs)which showed up-conversion(UC)from infrared to visible spectral region was developed.The NaYF4:Er NCs were synthesized in oleic acid(OA)and 1-octadecene(ODE)with Y2(CO3)3· xH2O,Er2(CO3)3· xH2O,Na2CO3 and NH4F as precursors.This proposed method was simple and less toxic compared with generally used method so far.The XRD results showed that the molar ratio of OA/ODE and the temperature were key factors for phase control of NaYF4:Er NCs.The UC emission spectra were obtained with the emission wavelength at about 980 nm(4I11/2→4I15/2),800 nm(4I9/2→4I15/2),660 nm(4F9/2→4I15/2)and 540 nm(4S3/2→4I15/2)from Er3+ ions,by excitation wavelength of 1550 nm.The slope values,n,in the pump-power dependence,showed that the emission at 980 and 800 nm were generated by 2-step UC and at 660 nm and 540 nm were 3-step UC.The optical process for the UC excitation was discussed.