Synthesis and Structural Investigation of （LaO）_3BO_3 with Eu^（3＋） as Luminescent Probe

Europium (Eu￣(3+)) doped polycrystalline (LaO)_3BO_3 has been synthesized by solid state reaction with Li_2CO_3 as flux at 1200℃ for 10 h in air. X- ray powder diffraction shows that ( LaO)_3BO_3 crystallizes in a monoclinic cell [a= 0. 69214 (9)nm , b=1. 2929(3) nm , c=1. 4590 (3 ) nm . β= 99. 35 (2)°,V= 1. 2882(4 ) nm￣3 and Z= 8] with a possible space group of P2_1/m or P2_1. The predominance of electric-dipole transition ￣5D_0→ ￣7F_2 in the fluorescence spectrum , as well as the splitting of the￣7F_j ground states of Eu￣(3+) reveals that the lanthanum atoms distribute in the sites with C_1 or C_s symmetry in this structure.

A novel long persistent luminescent material CaGeO_(3):Tb^(3+)with photo-stimulation properties

A novel green long afterglow material CaGeO_(3):Tb^(3+)was synthesized by high temperature solid phase method.According to the experimental results,CaGeO_(3):Tb^(3+)is a green long persistent luminescent(LPL)material with excellent performance.CaGeO_(3):Tb^(3+)shows LPL emission peak at 442,490.9,548.7,588.5 and 623.8 nm,corresponding to ^(5)D_(3) to^(7)F_(4)and^(5)D_(4)to^(7)F_(J)(J=6,5,4,3)transitions of Tb^(3+).Its CIE coordinates are(0.27,0.50),indicating that the afterglow emission is close to the light of green region.In addition,after the excitation source is turned off,the afterglow time is longer than 90 min.After an interval of 7 h,the photo-stimulation luminescence(PSL)can be observed by using 980 nm laser cyclic excitation.The thermoluminescence(ThL)results show that there are three types of traps in the material and their depths are 0.666,0.774 and 0.892 eV respectively,which are caused by the doping of Tb^(3+).All the results show that CaGeO_(3):Tb^(3+)is an excellent long afterglow luminescent material.

Sol-gel processed Ce^(3+), Tb^(3+) codoped white emitting phosphors in Sr_2Al_2SiO_7

Sr2Al2SiO7：Ce^3＋, Tb^3＋ white emitting phosphors were fabricated using the sol-gel method. X-Ray Powder Diffraction （XRD） analysis confirmed the formation of Sr2Al2SiO7：Ce^3＋, Tb^3＋. Scanning Electron Microscopy （SEM） observation indicated that the microstructure of the phosphor consisted of regular fine grains with an average size of about 0.5-1 μm. Luminescence properties were analyzed by measuring the photoluminescence spectra. The Ce^3＋, Tb^3＋-codoped Sr2Al2SiO7 phosphors showed four main emission peaks： one at 414 nm for Ce^3＋ and three at 482, 543, and 588 nm for Tb^3＋. The emission spectra of the samples with different doping concentrations showed that the Tb^3＋ emission was dominant because of the persistent energy transfer from Ce^3＋. The decay characteristic was better than that prepared by the solid-state process in the comparable condition. The codoped phosphor displayed long persistent white phosphorescence.

Ethanol-driven Room-temperature Synthesis of Potential Green-emitting Phosphors： a Case Study of Tb^3＋-doped CaHPO4

A novel green nanophosphor CaHPO4：Tb3＋ was synthesized via a room-temperatureco-precipitation route driven by ethanol solvent. X-ray powder diffraction （XRD）, scanningelectron microscopy （SEM） and photoluminescence spectroscopy （PL） techniques were utilizedto characterize the structure, morphology and fluorescence performance of the obtained powders.The results demonstrated that the prepared samples were well crystallized with triclinic phaseCaHPO4 structure and particle-like morphology. Photoluminescence measurements indicated thatCaHPOa：Tb3＋ had a strong absorption peak at 370 nm and exhibited characteristic emissions withseveral sharp peaks corresponding to the transitions 5D4-7FJ （jr = 6-3） of Tb3＋. Moreover, theluminescence optimum concentration for CaHPO4：Tb3＋ was determined to be 11 mol%, whichmight be a promising green-emitting ohosohor for display applications.

Synthesis and Properties of Tb^(3+)-Doped Ca_x Sr_(1- x)WO_4

Tb^(3+)-doped Ca_ x Sr_(1- x )WO_4 was prepared by solid state reaction and characterized by powder X-ray diffractometry. According to X-ray diffraction, this material belongs to tetragonal system, which is consistent with space group I4_1/a. Lattice parameters in the systems Ca_ x Sr_(1- x )WO_4 were found to vary linearly with compositions. The emission and excitation spectra were measured. The miscibility, luminescence properties of Tb^(3+)-doped Ca_ x Sr_(1- x )WO_4 and energy transfer mechanism were discussed.

Efficient production of ligand-free microscintillators at gram-scale for high-resolution X-ray luminescence imaging

The efficient production of high-quality scintillators with long radioluminescence afterglow is crucial for high-performance X-ray luminescence extension imaging.However,scaling-up the synthesis of ligand-free scintillators to fabricate large-area X-ray imaging screens for industrial applications remains a challenge.In this study,we report an efficient method to synthesize ligand-free,lanthanide-doped microscintillators by a one-pot reaction via the concentrated hydrothermal method.The as-synthesized microscintillators exhibit prolonged persistent radioluminescence for up to 30 days after X-ray exposure and remain high stability in air or water for more than 18 months without deterioration.Monte Carlo simulations indicate that the size effect is responsible for the excellent afterglow performance of the microscintillators.We employ these high-quality lanthanide-doped microscintillators to fabricate a large-area X-ray imaging detector using a blade-coating method,a spatial resolution of 24.9 lp/mm for X-ray imaging.Our study offers a solution for scaling-up the synthesis of low-cost microscintillators for practical applications.

Multi-color luminescence in Eu^3＋/Tb^3＋ co-doped ZnAl amorphous materials and their annealed samples

Multi-color luminescence basing on amorphous Eu^3＋/Tb^3＋ co-doped Zn-A1 hydroxides and their annealed samples were studied in detail. Results suggest that excellent red emissions due to E^u3＋ and green emissions attributed to Tb^3＋ appear under the excitation of favorable wavelength for all the as- prepared amorphous samples. Moreover, the emission intensity depends on the Eu^3＋/Tb^3＋ molar ratio. The samples annealed at 300, 500, and 700 ℃ still exhibit amorphous state, and multi-color lumi- nescence kept in the samples annealed at 300 ℃, while luminescence quenched for the samples annealed at 500 and 700 ℃. However, a broad emission ranging from 450 to 650 nm occurs in some samples annealed at 900 ℃. Further, the fluorescence decay and lifetimes for the as-prepared samples and the samples annealed at 300℃ were investigated. It is found that all the decay curves of emissions due to Tb^3＋ and Eu^3＋ present characteristic double exponential function despite their different lifetimes. The present work may be a good example for developing new multi-color even white light emitting materials.

Effect of calcinations temperature on the luminescence intensity and fluorescent lifetime of Tb^(3+)-doped hydroxyapatite(Tb-HA)nanocrystallines

Hydroxyapatite luminescent nanocrystallines doped with 6 mol.%Tb^(3+)(Tb-HA)were prepared via chemical deposition method and calcined at different temperature,and the effects of calcinations temperature on the luminescence intensity and fluorescent lifetime were studied.TEM image of Tb-HA revealed that the shape of nanocrystallines changed from needle-like to short rod-like and sphere-like with the increase of calcinations temperature;while the particles sizes decreased from 190 nm to 110 nm.the crystallinity degree increased.the typical emission peaks attributed to Tb^(3+) ions were observed in emission spectra of 6 mol.%Tb-HA under 378 nm excitation.the luminescent intensity of Tb-HA,which showed the fluorescence quenching,firstly enhanced and then decreased at 700℃;while the fluorescent lifetime increased firstly and then decreased after 600℃.Furthermore,the ratio of intensity between 545 nm and 490 nm corresponding to electric-dipole and magnetic-dipole transition(I_(R):I_(O))increases firstly and then decreases,which revealed that the proportion of substitute type and site of Ca^(2+) ions by Tb^(3+) ions were helpful to realize the substitute process and functional structure design.

AIE型荧光探针在Fe^(3+)检测上的应用——仪器分析设计性实验教学探究

实验通过紫外吸收与荧光光谱法研究了AIE型荧光探针四苯基-1,3-丁二烯对Fe^(3+)检测的选择性和灵敏度,对仪器分析实验中的荧光光谱法进行了探究与改进,属于设计性实验。该实验具有条件简单温和、荧光现象明显、重复性好、可操作性强等特点。根据课程需要和学生层次,采用阶梯式、模块化方式设置了实验教学内容,旨在通过过程化学习,强化学生的基础实验操作能力及自主学习能力,使科研、教学、趣味三者相互融合。

Luminescence property and magnetic resonance imaging of Gd_(2)O_(3):Tb^(3+) nanocrystals doped with Zn^(2+),Li^(+)

Gd_(2)O_(3):Tb^(3+) nanocrystal co-doped with Zn^(2+)and Li^(+) was prepared by the combination of polyol and solid-phase methods.The synthesized nanoparticles were characterized by X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM),photoluminescence(PL)spectra and magnetic resonance imaging(MRI).The results revealed that both Gd_(2)O_(3):Tb^(3+)/Zn^(2+) and Gd_(2)O_(3):Tb^(3+)/Li^(+) had cubic unit structures with a spherical shape,and the fluorescence intensity of the nanoparticles reached a maximum at a doping concentration of0.050 mmol%for Zn^(2+) and 2 mol%for Li^(+),respectively.In addition,the T_(1)/T_(2)(longitudinal/transverse relaxation time)-weighted MRI signals got enhanced due to the increased longitudinal relaxivity(r1)and transverse relaxivity(r2)after the doping by metal ions.Therefore,the materials reported here can be used for fluorescence and MR bimodal imaging,as tracers and for fluorescence detections.

Energy transfer and luminescent properties of Tb^(3+)and Tb^(3+),Yb^(3+)doped CNGG phosphors

In this work,calcium niobium gallium garnet(Ca_(3)Nb_(1.6875)Ga_(3.1875)O_(12)-CNGG)ceramic samples singledoped with Tb^(3+)and co-doped with Tb^(3+)and Yb^(3+)ions were sintered by the solid-state reaction method.The structural characterization of the samples was carried out by X-ray diffraction measurements.The optimal concentration of Tb^(3+)ions corresponding to the maximum luminescence in the green spectral range in CNGG:x at%Tb(x=0.1,0.5,1,2,3,4,and 5)was determined to be 4 at%.The timeresolved luminescence of the^(5)D_(4)level(Tb^(3+))in the CNGG:x at%Tb samples was analysed to explore the quenching mechanisms involved in the Tb^(3+)green emission.Co-doped CNGG:4 at%Tb,y at%Yb(y=0.5,2,4,6,8,and 10)ceramics were prepared and investigated.It is shown that CNGG:4 at%Tb,y at%Yb phosphors exhibit intense green luminescence under ultra-violet(UV),visible(VIS),and near-infrared(NIR)excitation,thus demonstrating the presence of simultaneous down-conversion(DC)and upconversion(UC)processes.The dependence of the UC luminescence intensity on the diode laser pumping power was measured and the results indicate a two-photon process based on cooperative energy transfer(CET).Under UV excitation,the lifetime of the^(5)D_(4)(Tb^(3+))level slowly increases with increase of Yb^(3+)concentration,suggesting the energy transfer from Yb^(3+)to Tb^(3+)ions,while under NIR excitation,the lifetime of the^(5)D_(4)(Tb^(3+))level decreases with increase of Yb^(3+)ions concentration,indicating the presence of a strong energy transfer from Tb^(3+)to Yb^(3+)ions.The highest energy transfer efficiency ofη_(ET)≈42%was determined for the CNGG:4 at%Tb,10 at%Yb sample.The obtained results indicate that CNGG:(Tb^(3+),Yb^(3+))could be efficient new yellowish-green-emitting phosphors.

铽离子荧光探针对钙调素的研究与进展

Tb3+离子能够取代钙调素中的钙离子而影响其生物功能,因此可作为荧光探针对钙调素进行研究。概述了Tb3+离子荧光探针对钙调素的研究进展情况。

Upconversion multicolor tuning of NaY(WO_4)_2:Tb^(3+) with Eu^(3+) doping

A series of Tb3＋ and Eu3＋ co-doped NaY（WO4）2 phosphors were synthesized by hydrothermal reactions.The crystal structure,morphology,upconversion luminescent properties,the energy transfer from Tb3＋ to Eu3＋ions and the 5 D4→ 7 F5 transition of the Tb3＋ ion in NaY（WO4）2：Tb3＋,Eu3＋ phosphors were investigated in details.The results indicate that all the synthesized samples are of pure tetragonal phase NaY（WO4）2.Furthermore,the micrometer-sized needle spheres and excellent dispersion of the particles are obtained by adding polyethylene glycol（PEG-2000） as the surfactant.Phosphors of NaY（WO4）2：Tb3＋,Eu3＋ exhibit the492 nm blue emission peak,546 nm green emission peak,595 nm orange emission peak and 616 nm red emission peak under 790 nm excitation.The energy transfer from Tb3＋ to Eu3＋ is a resonant transfer,in which electric dipole-dipole interaction plays a leading role.By adjusting the doping concentration of Eu3＋ in NaY（WO4）2： 1.0 mol%Tb3＋,xmol%Eu3＋ phosphors,the emitting color of UC phosphors can be tuned from green to red.

LiZnPO_4:Tb^(3+),Ce^(3+) green phosphors with high efficiency

Tb^3＋ and Ce^3＋ co-activated LiZnPO4 phosphors with high luminescence efficiency were synthesized by a high temperature solid-state reaction at 1000 ℃ for 3 h. The XRD patterns, photoluminescence spectra and SEM were recorded and the effects ofTb^3＋and Ce^3＋ concentration, sintering condition on the luminescent properties of as-synthesized phosphors were investigated. The emission spectra under ultraviolet （200-300 nm） radiation showed a dominant peak at 543 nm attributed to the ^5D4→^7F5 transition of Tb^3＋, which was greatly enhanced by the co-doping of Ce^3＋, indicating that there occurred an efficient non-radiative energy transfer from Ce^3＋ to Th^3＋. The optimal doping concentrations of Tb^3＋ and Ce^3＋ were determined to be 9% and 10%, respectively.

Terbium-doped heavy metal glasses for green luminescence

Compositional-dependent heavy metal lead borate glasses doped with Tb^3＋ ions were investigated. Green luminescence related to main ^5D4→^7F5 （543 nm） transition was registered under excitation of ^5D3 state of Tb^3＋ ions. Based on excitation and luminescence measurements, several spectroscopic parameters for Tb3＋ ions were examined as a function of heavy metal PbO content. Luminescence decay analysis indicated that the ^5D4 luminescence lifetime of Tb^3＋ reduced from 2.83 to 1.42 ms, when PbO：B203 ratio was changed from 1：1 to 4：1.

Asymmetry ratio as a parameter of Eu^3＋ local environment in phosphors

Study of the local environment of certain ion is quite a complex problem. Due to the unique luminescent properties, Eu^3＋ ions can be used as a structural probe. In this paper, effect of doping concentration,excitation wavelength and excitation mechanism on asymmetry ratio was systematically studied using Y3Al5O12：Eu^3＋, YVO4：Eu^3＋ and Y2O3：Eu^3＋nanophosphors. The asymmetry ratio gives information about the local surrounding and environmental changes around the Eu^3＋ ions. Asymmetry ratios of YAG：Eu^3＋and YVO4：Eu^3＋ nanopowders were calculated using standard technique and the obtained average values were found to be 0.75 and 8.2, respectively. However, it is found that standard method of asymmetry ratio calculation is suitable only for samples where all Eu^3＋ ions occupy one site. The ＂multisite model＂ of asymmetry ratio calculation was developed and used for Y2O3：Eu^3＋ nanocrystalline powders. Average value of asymmetry ratio for Eu^3＋ ions occupied ＂normal＂ sites is 6.0 and for Eu^3＋ ions occupied ＂defect＂sites is 2.3.