Photoactive rare earth (Eu3+, Tb3+) hybrids with organically modified silica covalently bonded polymeric chain

1,3-Bis(2-formylphenoxy)-2-propanol (BFPP) is grafted to 3-(triethoxysilyl)-propyl isocyanate (TESPIC) to prepare the organic precursor BFPP-Si. Then, the organic precursor BFPP-Si is coordinated with rare earth ion to obtain the luminescent center RE-BFPP-Si. Allylamine monomer (AM) is modified by TESPIC to form the precursor AM-Si which is then polymerized with the benzoyl peroxide as the initiator to form the polymer precursor PAM-Si. The other polymer precursor polyethylene glycol (PEG)-Si is achieved through the grafting reaction between PEG and TESPIC. Subsequently, the hybrid materials RE-BFPP-Si-PAM or RE-BFPP-Si-PEG are assembled in which RE-BFPP-Si and PAM-Si or PEG-Si connected with Si-O bonds through sol-gel process and characterized with scanning electronic microscopy, X-ray diffraction, and TG-DSC curves. Their photophysical properties are especially studied in details, indicating that the introduction of organic polymer chain is favorable for the luminescence lifetime and quantum efficiency.     

Photofunctional Eu3+/Tb3+ hybrids through sulfoxide linkages: coordination bonds construction, characterization and luminescence

New kinds of organic-inorganic hybrid materials consisting of rare earth (Eu(3+), Tb(3+)) complexes covalently bonded to a silica-based network have been obtained by a sol-gel approach. Three novel versatile molecular building blocks containing sulfoxide organic units have been synthesized by methylene modification reaction, which are used as the ligands of rare earth ions and also as siloxane network precursors. The obtained hybrids are characterized by chemical analysis and spectroscopic methods such as FTIR and UV; XRD and SEM. Photoluminescence measurements on the prepared hybrids were performed showing the intra-4f(n) emission in the visible (Eu(3+), Tb(3+)) region and in all the cases being sensitized by the sulfoxide ligands. The emission quantum efficiency and the Judd-Ofelt intensity parameters of Eu(3+) hybrid materials were also investigated in detail.     

Assembly of novel Tb3+/Eu3+ sensitized cellulose gels and their emission behaviors

In this paper, a novel luminescent hydrogel was successfully prepared by incorporating Tb-HSA (HSA = Human Serum Albumin) complex into cellulose host. The green luminescence intensities of Tb(III) exhibited on–off changes in terms of pH variation. At the same time, europium activated phosphor (GdVO₄:Eu³⁺) was immobilized into the cellulose hydrogels through two approaches. The photophysical properties of luminescent gels with the temperature variation were investigated by fluorescence. The new group of soft materials will display task-specific usages in sensing fields.     

Photo-modulated wide-spectrum chromism in Eu3+ and Eu3+/Tb3+ photochromic coordination polymer gels: application in decoding secret information

Photo-switching emission of photochromic materials has paramount importance in the field of optoelectronics. Here, we report synthesis and characterization of a dithienylethene (DTE) based photochromic low molecular weight gelator (LMWG) and self-assembly with lanthanide (Eu³⁺ and Tb³⁺) ions to form a photochromic coordination polymer gel (pcCPG). Based on DTE ring opening and closing, the TPY-DTE gel shuttles from pale-yellow coloured TPY-DTE-O to dark blue coloured TPY-DTE-C and vice versa upon irradiating with UV and visible light, respectively, and both the photoisomers show distinct optical properties. Furthermore, integration of Eu³⁺ and Tb³⁺ lanthanides with TPY-DTE resulted in red and green emissive Eu-pcCPG (Q.Y. = 18.7% for the open state) and Tb-pcCPG (Q.Y. = 23.4% for the open state), respectively. The photoisomers of Eu-pcCPG exhibit photo-switchable spherical to fibrous reversible morphology transformation. Importantly, an excellent spectral overlap of the Eu³⁺ centred emission and absorption of DTE in the closed form offered photo-switchable emission properties in Eu-pcCPG based on pcFRET (energy transfer efficiency >94%). Further, owing to the high processability and photo-switchable emission, the Eu-pcCPG has been utilized as invisible security ink for protecting confidential information. Interestingly, mixed Eu³⁺/Tb³⁺ pcCPG exhibited photo-modulated multi-spectrum chromism reversibly where the colour changes from yellow, blue, and red to green and vice versa under suitable light irradiation.

A lanthanide based photochromic coordination polymer gel (pcCPG) material has been developed which showed photomodulated colour change based on pcFRET and has the potential to be employed for decoding secret information.     

Preparation and Luminescence Properties of Color-tunable Single-phased LaPO4: Eu3+/Tb3+ Phosphors

A novel series of color-tunable single-phased phosphors La_1-x-yPO₄:xEu³⁺/yTb³⁺(x=0, 0.01, 0.02, 0.03, 0.04, 0.05; y=0, 0.05, 0.10, 0.15, 0.20) was synthesized via microwave-assisted co-precipitation method with diammonium hydrogen phosphate as precipitant. The morphology, crystal structure and photoluminescence properties of the as-prepared samples were characterized by means of X-ray diffraction(XRD), scanning electron microscopy(SEM) and fluorescence spectrophotometer. The results reveal that the as-synthesized samples calcined at 1100℃ display spherical morphology with uniform distribution. Upon excitation with 350 nm ultraviolet radiation, the LaPO₄:Eu³⁺/Tb³⁺ phosphors showed a green light peaking at 543 nm assigned to the characteristic ⁵D₄-⁷F₅ emission of Tb³⁺ and a red light peaking at 591 nm corresponding to the characteristic ⁵D₀-⁷F₁ emission of Eu³⁺ simultaneously. For the Eu³⁺/Tb³⁺ co-activated phosphors, Tb³⁺ acts as an efficient sensitizer to enhance the emission intensity of Eu³⁺ ions. The energy transfer mechanism and the emission color tunability of LaPO₄:Eu³⁺/Tb³⁺ have been studied. The results indicate that a color-tunable luminescence(from green to white to red) can be achieved by adjusting the Eu³⁺/Tb³⁺ doping ratio in the LaPO₄ host matrix.     

Multi-walled carbon nanotube-based ternary rare earth (Eu3+, Tb3+) hybrid materials with organically modified silica-oxygen bridge

A series of ternary rare earth (Eu(3+), Tb(3+)) complexes are covalently coated to the 3-aminopropyltriethoxysilane functionalized multi-walled carbon nanotube (MWCNT) by a simple in situ sol-gel method by the bifunctional silylated monomer TTA-Si and TAA-Si (TTA-Si and TAA-Si are 3-(triethoxysilyl)propylisocyanate (TEPIC) modified thenoyltrifluoroacetone (TTA) and trifluoroacetylacetone (TAA), respectively). The resulting materials are characterized by Fourier transform infrared spectra, scanning electronic microscope, transmission electron microscope, thermogravimetric analysis, ultraviolet visible diffused reflection measure, photoluminescence spectra, and X-ray diffraction. The photoluminesce measurements indicated that these hybrids exhibit characteristic red and green luminescence originating from the corresponding ternary rare earth ion (Eu(3+), Tb(3+)). The luminescence quenching effect of MWCNT networks have been successfully restrained by coating a relatively thicker silica-oxygen-based organic-inorganic complex. Furthermore, the fluorescence lifetimes and emission quantum efficiencies of Eu(3+) hybrid materials are also determined.     

NaY(WO4)2:Eu3+/Tb3+/Tm3+白色荧光粉的制备与发光性能

采用溶剂热法合成了一种单一相白色荧光粉NaY(WO4)2:Eu3+,Tb3+,Tm3+.通过X射线衍射(XRD)、扫描电镜(SEM)、X射线能谱(EDS)及荧光光谱(PL)对制备的系列样品的物相、形貌和荧光性质进行了表征.结果表明:在荧光粉NaY(WO4)2:x％Eu3+,4％Tb3+,1％Tm3+(x=5,10,15,20)中,随着Eu3+掺入量的增加,发光从绿光区进入白光区.同时观察到Tb3+到Eu3+的有效能量传递.     

Eu^2＋在BaF2—xYF3体系中的光谱性质及其对Tb3＋的能量传递

研究了钡钇复合氟化物体系中Ｅｕ＾２＋的光谱性质和变化规律，讨论了影响Ｅｕ＾２＋光谱的因素，特别是氧的存在对Ｅｕ＾２＋激发和发射能量的影响，发现在ＢａＹＦ５基质中Ｅｕ＾２＋对Ｔｂ＾３＋的有效参量传递。     

Tunable luminescence and energy transfer process between Tb3+ and Eu3+ in GYAG:Bi3+, Tb3+, Eu3+ phosphors

A series of Eu³⁺ ions co-doped (Gd_0.9Y_0.1)₃Al₅O₁₂:Bi³⁺, Tb³⁺ (GYAG) phosphors have been synthesized by means of solvothermal reaction method. The XRD pattern of GYAG phosphor sintered at 1500 °C confirms their garnet phase. The luminescence properties of these phosphors have been explored by analyzing their excitation and emission spectra along with their decay curves. The excitation spectra of the GYAG:Bi³⁺, Tb³⁺, Eu³⁺ phosphors consists of broad bands in the shorter wavelength region due to 4f⁸ → 4f⁷5d¹ transition of Tb³⁺ ions overlapped with 6s² → 6s¹6p¹ (¹S₀ → ³P₁) transition of Bi³⁺ ions and the charge transfer band of Eu³⁺–O^2?. The present phosphors exhibit green and red colors due to ⁵D₄ → ⁷F₅ transition of Tb³⁺ ions and ⁵D₀ → ⁷F₁ transition of Eu³⁺ ions, respectively. The emission was shifted from green to red color by co-doping with Eu³⁺ ions, which indicate that the energy transfer probability from Tb³⁺ to Eu³⁺ ions are dependent strongly on the concentration of Eu³⁺ ions.     

Luminescence of Tb3+ and Eu3+ doped amorphous zinc benzoates

The Tb(3+) and Eu(3+) doped amorphous zinc benzoate were prepared. Their infrared absorption, emission and excitation spectra were measured. The luminescence mechanisms of Tb(3+) and Eu(3+) in the amorphous substrate were discussed. The bonding modes of OCO group to Zn(2+) ion have two of symmetric and asymmetric bridging bidentate. The energy of the S(1) pi,pi* excited state of benzene ring can be transferred to Tb(3+) and Eu(3+) ion, and results in characteristic emission from the 5D(4)-->(7)F(j) of Tb(3+) and 5D(0)-->(7)F(j) of Eu(3+), respectively.     

Photoluminescent Property Effect of Sc3+ on Er3+/y3+/yb3+ Doped Al2O3 Powders

The photoluminescence (PL) property effect of Sc3+ on the Er3+/Y3+/Yb3+ doped Al2O3 powders prepared by sol-gel method has been investigated. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) implied that the distribution of dopants (Er3+ , Y3+ , Yb3+ , Sc3+) was improved effectively with the rise of Sc3+ concentration. The Fourier transform infrared spectra (FTIR) results demonstrated that the ligand around the quenching center -OH and the population of -OH were altered by introducing different amounts of Sc3+ . The PL intensity centered at 1530 nm was increasingly improved with the rise of Sc3+ concentration, as well as the corresponding full widths at the half maximum (FWHM) and lifetime. The optimized PL intensity was 4.7 times higher than that non-Sc3+ doped sample for the Al2O3 powders codoped with 10mol% Sc3+ . This material can be promising candidates for optical fiber amplifier.     

LaPO4:Eu3+纳米粒子的多醇法合成及其光致发光性能研究

以一缩二乙二醇为溶剂，采用多醇法（polyol method）合成LaPO4：Eu^3＋纳米发光材料，利用XRD、FE．SEM、TG-DTA、Uv-vis光谱、光致发光光谱（PL）及寿命等手段进行了表征。结果表明：所得到的材料结晶完好，具有LaPO4的独居石型结构；粒子的形貌为球形，其粒径约为25nm；在波长为258nm的紫外光激发下，其发射光谱由Eu^3＋的5D0^-7FJ（J=1，2，3，4）特征发射组成，在592nm处的磁偶极跃迁（5D0^-7F1）最强，表现为Eu^3＋的橙-红特征发射；LaP04：Eu^3＋纳米粒子中Eu^3＋的最佳掺杂浓度为5％（摩尔比）；Eu^3＋的光致发光衰减曲线符合单指数行为，其寿命（τ）为3．9ms。     

Preparation of luminescent and mesoporous Eu3+/Tb3+ doped calcium silicate microspheres as drug carriers via a template route

Luminescent and mesoporous Eu(3+)/Tb(3+) doped calcium silicate microspheres (LMCS) were synthesized by using mesoporous silica spheres as the templates. The LMCS and drug-loaded samples were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), N(2) adsorption/desorption, and photoluminescence (PL) spectra. The results reveal that the LMCS have uniform spherical morphology with a diameter around 400 nm and the mesopore size of 6 nm. The prepared samples exhibit little cytotoxicity at concentrations below 5 mg mL(-1) via MTT assay. In addition, drug storage/release properties of the LMCS were demonstrated for ibuprofen (IBU). The obtained LMCS can be used to encapsulate drugs and release them. Under excitation by UV light, the IBU-loaded samples still show the characteristic (5)D(0)-(7)F(1-3) emission lines of Eu(3+) and the characteristic (5)D(4)-(7)F(3-6) emission lines of Tb(3+). The PL intensity of Eu(3+) in the drug carrier system increases with the cumulative released amount of IBU, making the drug release able to be tracked or monitored by the change of luminescence of Eu(3+). The LMCS reported here with mesoporous structure, good biocompatibility and luminescent property can be a promising drug delivery carrier.     

一种新型Eu3+ 和Zn2+ 双金属杂核配合物的结构与发光性质

合成了一种新型双金属杂核配合物Eu(TTA)3Zn(Salen).H2O(Salen=双水杨醛缩乙二胺,TTA=2-噻吩甲酰三氟丙酮),并对其进行了结构和荧光性能表征.配合物的晶体属于三斜晶系,Pī空间群.中心Eu(Ⅲ)离子与六个TTA分子的氧原子和Salen分子的两个酚氧原子配位,形成8配位的扭曲四方反棱柱构型.Zn(Ⅱ)离子与Salen分子中的两个酚氧原子和两个氮原子以及一个水分子配位,形成五配位的扭曲的四方锥构型.配合物Eu(TTA)3Zn(Salen).H2O的发光量子效率(18.0%)较配合物Eu(TTA)3.2H2O(12.5%)发光量子效率有明显提高,说明第二配体Zn(Salen).H2O对中心离子有较强的敏化发光作用.     

Tailoring of polychromatic emissions in Tb3+/Eu3+ codoped NaYbF4 nanoparticles via energy transfer strategy for white light-emitting diodes

The polychromatic emission and wide-range color tuning in the luminescent nanoparticles are currently of crucial importance, due to the development of color and white light-emitting diode (LED) devices, based on such lanthanide-doped nanostructured materials. By utilization of precipitation method, Tb³⁺-doped and Tb³⁺/Eu³⁺-codoped NaYbF₄ nanoparticles (i.e. NPs) are synthesized. For Tb³⁺-doped NaYbF₄ NPs excited by 377 nm, green emission originating from Tb³⁺ is observed, where its optimum state is obtained when Tb³⁺ content is 25 mol% and the concentration quenching mechanism is found by electric dipole-dipole interaction. Moreover, due to the existence of energy transfer between Tb³⁺ and Eu³⁺, polychromatic emissions are realized in Tb³⁺/Eu³⁺-codoped NaYbF₄ NPs as Eu³⁺ content increases. Through analyzing emission decay times and emission spectra, it was confirmed that the energy transfer mechanism in the synthesized NPs is governed mainly by electric dipole-dipole interaction. Furthermore, the resultant NPs also own strong resistance to temperature, which is verified by temperature-dependent emission spectra, and the activation energies of Tb³⁺ and Eu³⁺ are 0.206 and 0.207 eV, respectively. In addition, by employing designed NPs as yellow-emitting components, the fabricated white-LED emits brightness warm white light with color coordinate of (0.385, 0.380), high color rendering index of 84.3 and low correlated color temperature of 3903 K. This work does not only offer an available route to develop NPs with polychromatic emissions but also devise promising luminescent materials for improving the performance of the phosphor-converted white-LED.     

Optical characterization of Eu3+ and Tb3+ ions doped zinc lead borate glasses

This paper reports on the spectral analysis of Eu3+ or Tb3+ ions (0.5 mol%) doped heavy metal oxide (HMO) based zinc lead borate glasses from the measurement of their absorption, emission spectra and also different physical properties. From the XRD, DSC profiles, the glass nature and glass thermal properties have been studied. The measured emission spectrum of Eu3+ glass has revealed five transitions (5D0-->7F0, 7F1, 7F2, 7F3 and 7F4) at 578, 591, 613, 654 and 702 nm, respectively, with lambdaexci=392 nm (7F0-->5L6). In the case of Tb3+:ZLB glass, four emission transitions such as (5D4-->7F6, 7F5, 7F4 and 7F3) that are located at 489, 542, 585 and 622 nm, respectively, have been measured with lambdaexci=374 nm. For all these emission bands decay curves have been plotted to evaluate their lifetimes and the emission processes that arise in the glasses have been explained in terms of energy level schemes.     

沉淀法合成t-LaVO4∶Eu3+及其光致发光性质研究

用沉淀法在不同pH值下选择性合成了m-和t-LaVO4:Eu3+,合成过程未使用添加剂.用XRD、SEM、PL对样品进行了表征,并与水热法所制备样品的性质进行了比较.结果表明,样品在280 nm紫外光激发下能发射600～620 nm窄带红光,t-LaVO4:Eu3+发光性能远比m-LaVO4:Eu3+优越;pH值是选择性合成t-LaVO4:Eu3+的关键,pH值在6～9范围内,沉淀法与水热法都可得到t-LaVO4:Eu3+,其中pH值为7时样品发光强度最高.样品形貌对光致发光性质有重要影响,沉淀法所得到的t-LaVO4:Eu3+具有规则的形貌,尺寸为亚微米级.延长陈化时间可增强样品发光强度,常温下陈化12 h所得样品的发光强度与180℃水热2 h样品相近.Eu3+掺杂量也是影响样品发光性质重要因素,其最佳掺杂浓度为物质的量分数5%.t-LaVO4:Eu3+在600℃以下结构稳定,煅烧后样品发光强度不会下降.     

Eu3+和Tb3+在LnBaB9O16中的紫外和真空紫外发光性质

研究了Tb3+和Eu3+在LnBaB9O16(Ln=La,Gd,Y,Lu)中的紫外和真空紫外光谱性质.X射线粉末衍射数据指标化结果表明,LnBaB9O16(Ln=La,Gd,Y,Lu)系列化合物属于三方晶系.Eu3+的荧光光谱结果表明,LaBaB9O16和GdBaB9O16中稀土离子占据非中心对称的格位,Eu3+在其中的特征发射以5D0→7F2电偶极跃迁为主;而在YBaB9O16和LuBaB9~O16中稀土离子占据中心对称性的格位,Eu3+在其中的特征发射以5D0→7F1磁偶极跃迁为主.Tb3+在LaBaB9O16和GdBaB9O16中的发射为5D3→7F0和5D4→7F1(J=0～6)辐射跃迁,在YBaB9O16和LuBaB9O16中只能观察到5D4→7F1(J=3～6)辐射跃迁.与Eu3+的发光性质相反,Tb3+占据非中心对称的格位时的发射强度比占据中心对称的格位时要弱得多.Eu3+和Tb3+掺杂的样品在真空紫外波段的吸收弱.     

GdF3∶Eu3+/NaGdF4∶Eu3+纳米晶的水热合成及发光性质

采用水热法,以聚乙二醇(400)为分散剂,以NaOH和HNO3溶液调节初始溶液pH值,合成GdF3∶Eu3+和NaGdF4∶Eu3+纳米晶。XRD和SEM结果表明:在酸性溶液(pH=3,5)、中性溶液(pH=7)和碱性溶液(pH=9)中,分别获得具有正交结构的GdF3∶Eu3+纳米晶,GdF3∶Eu3+和NaGdF4∶Eu3+混合晶,六方结构NaGdF4∶Eu3+棒状微米晶。根据Scherrer公式估算pH=3和pH=5时制备纳米晶的一次性粒径分别为49和28 nm。样品的发射光谱结果表明:特征发射峰来自于5D2、5D1、5D0到7FJ跃迁。在主晶相为GdF3样品中,主发射峰来自于Eu3+的5D0→7F1的磁偶极跃迁;晶相为NaGdF4样品的主发射峰来自于Eu3+的5D0→7F2电偶极跃迁。5D0→7F1和5D0→7F2跃迁发射相对强度比值显示:Eu3+在NaGdF4晶体中的格位对称性下降。激发光谱显示出Gd3+和Eu3+具有较好的能量传递。     

Eu3+/Tb3+和Eu3+/Pr3+共掺杂P(MMA-co-St)的荧光性能的研究

将不同荧光性能的铽(Tb)、镨(Pr)离子分别与铕(Eu)离子混合，以三异丙氧基稀土的形式掺杂P(MMA-CO-St)共聚物，研究Eu^3 ／Tb^3 和Eu^3 ／pr^3 共掺杂P(MMA-CO-St)的荧光性能的变化情况．结果表明，Eu^3 ／Tb^3 掺杂的P(MMA-CO-St)中，Tb^3 作为能量给予体，Eu^3 作为能量接受体，能量转移的结果使Eu^3 特征荧光显增强；Eu^3 ／pr^3 掺杂的P(MMA-CO-St)中，Eu^3 的能量向pr^3 转移，致使Eu^3 的特征荧光猝灭，pr^3 的荧光略为增强．