Hydrothermal synthesis,structure study and luminescent properties of YbPO₄:Tb³⁺ nanoparticles

YbPO4:Tb3+ were synthesized by mild hydrothermal method.The luminescent properties,morphologies and structure of the obtained powders were characterized by photoluminescence(PL) spectra,FESEM,X-ray diffractometer(XRD) and FTIR.The results showed that the prepared YbPO4:Tb3+ nanoparticles were pure tetragonal phase and the average grain size varied with increasing of Tb3+ concentration.Hydrothermal temperature was revealed to be the key factor to enhance the emission intensity of YbPO4:Tb3+ phosphors.The spherical nanoparticles could be effectively excited by near UV(369 nm) light and exhibited green performance at 543 nm(5D4→7F5),489 nm(5D4→7F6) and 586 nm(5D4→7F4).The CIE chromaticity was calculated to be x=0.298,y=0.560.The YbPO4:Tb3+ nanoparticles exhibited potential to act as UV absorber for solar cells to enhance the conversion efficiency.     

Hydrothermal synthesis and luminescent properties of BaMoO_4:Sm~(3+) red phosphor

Trivalent samarium doped barium molybdate(BaMoO_4:Sm~(3+)) red phosphor was successfully synthesized by hydrothermal method. The crystal structure, morphology and photoluminescent property were characterized by X-ray diffraction, field environmental scanning electron microscopy and photoluminescence spectroscopy. The results indicated that the synthesized BaMoO_4:Sm~(3+)phosphor consisted of a pure phase with an octahedral structure. The main excitation peaks were located at 362, 404, 445 and 477 nm, respectively, and were obviously observed. The main emission peaks were located at 533, 566, 602 and 646 nm, respectively. The phosphors exhibited a red performance at 646 nm, which was appropriate for the ultraviolet-light emitting diode(UV-LED) and blue LED. The luminescent intensity of BaMoO_4:Sm~(3+) increased with an increase in the doping amount of Sm~(3+). The luminescent intensity had the optimal value for x=0.03. When the doping amount of Sm~(3+) was further increased, the concentration quenching phenomenon was observed. Monovalent lithium(Li+) cation was used as a charge compensator. The luminescence intensity first increased with increasing Li+ doping concentration, and then decreased. The optimal content of Li+ was about 2%. The BaMoO_4:Sm~(3+) phosphor prepared in this study could act as superior red phosphor for white LEDs.     

Energy transfer and luminescent properties of Tb3+ and Tb3+, Yb3+ doped CNGG phosphors

In this work,calcium niobium gallium garnet(Ca₃ Nb_1.6875Ga_3.1875O₁₂-CNGG) ceramic samples singledoped with Tb³⁺ and co-doped with Tb³⁺ and Yb³⁺ 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 Tb³⁺ ions corresponding to the maximum luminescence in the green spectral range in CNGG:...     

InBO3:Tb3+荧光粉的合成及其发光性质

硼酸盐体系绿色荧光粉具有发光效率高、光色纯、烧结温度低、合成简便、粒径适中等优点,广泛用于等离子彩色电视机.应用高温固相反应法合成In0.98Tb0.02BO3荧光粉,并研究其中Tb3 的光谱性质及能量传递现象.发现激发光谱中Tb3 在274nm处有一最强4f→5d激发峰,能有效地吸收能量.发射光谱在550nm处有一最强峰,属于Tb3 的5D4→7F的跃迁,发绿光.发射峰高而窄,说明荧光粉In0.98Tb0.02BO3发光强度高,且只有一个峰,说明发光颜色纯,有一定的开发价值.还研究了几种因素对In0.98Tb0.02BO3荧光粉相对亮度的影响并得出了合成In0.98Tb0.02BO3荧光粉的最佳实验条件: 焙烧温度1300℃,焙烧时间4h.     

Electrospinning synthesis and luminescent properties of Lu2O3:Eu3+ nanofibers

One-dimensional Lu₂O₃:Eu³⁺ nanofibers were prepared by electrospinning followed by high-temperature calcinations. Thermogravimetric and differential thermal analysis, X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, photoluminescent spectra and decay curves were used to characterize the samples. Results showed that samples began to crystallize at ～500 °C and crystallized completely around 1000 °C. The average diameter of nanofibers (1000 °C annealed) was about 55 nm and the particle size of Lu₂O₃:Eu³⁺ increased with increasing annealing temperature. Under ultraviolet excitation, nanofibers exhibited typical red emission of Eu³⁺ in Lu₂O₃. The effect of heat-treatment temperature on luminescent properties of nanofibers was also discussed.     

EXAFS investigation and luminescent properties of nanosized Tb: Lu2O3 phosphors

Nanosized terbium doped Lu2O3 phosphors were synthesized via a modified co-precipitation processing.The as-prepared Tb:Lu2O3 phosphors was consisted of well crystallized nanosized sphere particles with a diameter of about 30 nnx Local structure of Tb ions in Lu2O3 lattice was investigated by an analytical approach based on Fourier transformation of the extended X-ray absorption fine structure(EXAFS) data.X-ray near edge structure (XANES) spectra suggested that all Tb ions doped were tervalonce.EXAFS results indicated that Tb ions have entered the Lu2O3 cubic lattice by means of solid solution.The coordination number and first shell Tb-O distance dropped with the increasing of Tb concentration.Emission spectra of the phosphors was shown to be typical for Tb3+ with main components at 542,550 and 490 nm,derived from irradiative relaxation of 5D4 level.The emission intensity decreased severely with the increasing of Tb concentration from 1 mol.% to 15 tool.%,suggesting a significant concentration quenching above 1 mol.% Tb.The reduction of emission intensity was interpreted by higher distortion derived relaxation among the surface state resident Tb3+ ions.     

Hydrothermal synthesis and luminescent properties of Li_xEu_xSr_（1-2x）MoO_4 red phosphor

LixEuxSr1-2xMoO4 red phosphors were synthesized via a facile hydrothermal method with various reaction time and ion contents of Eu3+ and Li+.As-synthesized samples were characterized by X-ray diffraction(XRD),thermogravimetry(TG),field emission scanning electron microscopy(FE-SEM) and fluorescence spectrophotometry.The XRD results revealed the formation of scheelite-like phosphor structures.The excitation spectra indicated the presence of two main excitation peaks located at 396 and 466 nm,suggesting that t...     

表面活性剂对ZnWO4：Tb3+绿色荧光粉发光性能的影响

采用水热法合成应用于荧光灯的绿色荧光粉 ZnWO4：Tb3+。通过X 射线粉末衍射分析仪（XRD）,扫描电子显微镜（SEM）和荧光光谱仪,系统考察不同表面活性剂条件下合成的ZnWO4：Tb3+绿色荧光粉。结果表明,不同表面活性剂条件下,采用水热法合成的产品均为纯ZnWO4结构,Tb3+掺杂并不改变钨酸锌结构;荧光光谱仪对样品的激发和发射以及荧光衰减曲线测定表明,表面活性剂PEG-2000条件下合成的荧光粉,其发光强度增强最有效,采用PVP 为表面活性剂合成ZnWO4：Tb3+的荧光粉寿命较采用PEG-2000和CTAB 为表面活性剂合成的长。综合发光强度和荧光寿命的影响,选PVP为表面活性剂最佳。     

SiO_2∶Eu~(3+)的制备与发光性能研究

以三氧化二铕和正硅酸乙酯为原材料,利用溶胶-凝胶法、高温机械力化学法合成了SiO_2∶Eu~(3+)粉体.用X射线衍射(XRD)、扫描电镜(SEM)表征了材料的结构和形貌,采用激发光谱、发射光谱对荧光粉体的发光性能进行了测量.结果说明:溶胶-凝胶法、高温机械力化学法合成样品的发光性能随着热处理温度的增加先增强后减弱,分别在900℃和600℃达到最好,粉体平均粒度分别为2μm与1μm.与溶胶-凝胶法比较,高温机械力化学法的制备温度降低了300℃.且利用高温机械力化学法制备的样品的发光性能要好于溶胶-凝胶法制备的样品.     

Luminescence properties of BaAl12O19:Tb,Ce and energy transfer between Ce3+, Tb3+

BaAl₁₂O₁₉:Tb,Ce phosphors were prepared by sol-gel technique, the crystalline structures of samples characterized by XRD, and the luminescence properties and energy transfer between Ce³⁺ and Tb³⁺ were investigated. The results indicated that the emission intensity and the excitation wavelength range of Tb³⁺ increased when Ce³⁺ was doped. It demonstrated that the Ce³⁺ added in the BaAl₁₂O₁₉:Tb could deliver energy to Tb³⁺, and Ce³⁺ was not luminous by itself. The relative emission intensity of Tb³⁺ at wavelength of 548 nm was the strongest by Tb³⁺/Ce³⁺ ratio of 2:1, when excited at 310 nm, which was the characteristic adsorption wavelength of Ce³⁺.     

Uniform YF_3 nanorods:Synthesis,luminescent properties and cytotoxicity study

Uniform YF3 nanorods composed of nanoparticles were successfully prepared via a facile solvothermal method with ethanol as solvent and tetrabutyl ammonium fluoride(TBAF) as fluorine source.The products were characterized with powder X-ray diffraction(XRD),scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The nanorods were with diameters of ca.60 nm and lengths ranging from 200 to 350 nm.Eu3+ and Tb3+ doped YF3 nanorods were also prepared and their photoluminescence properties were ...     

Re-determination of the crystal structure of Ca2Y8Si6O26 and study on the luminescent properties of Ca2Y8Si6O26:Tb3+

The crystal structure of silicate oxyapatite Ca₂Y₈Si₆O₂₆ was indexed as hexagonal, space group P6₃/m, α=0.93515 nm, c=0.67872 nm, α=β=90°, γ=120°, V=0.5138692 nm³. Three strong peaks located at 32.079°, 32.595°, and 50.104° with d=2.7903, 2.74649, 1.8194 was in accordance with (211), (112), and (213) planes. The optimum concentration of Tb³⁺ in Ca₂Y₈Si₆O₂₆ to yield highest photoluminescence intensity was 10 mol.% of Y³⁺. The corresponding excitation spectrum consisted of an intense broad band from 220 to 260 nm. The photoluminescence measurements showed that the green emission originated from ⁵D₄?⁷F₅ was predominant in the measured range with strong doublet lines at 543 and 549 nm.     

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。     

One-step synthesis of hollow PEI-NaBiF_4:Yb~(3+)/Er~(3+) upconversion nanoparticles for water-responsive luminescent probe

Novel PEI-modified NaBiF_4:Yb~(3+)/Er~(3+)upconversion nanoparticles(UCNPs) with hollow structure were prepared by a surface modification free one-step solvothermal method and applied as a luminescent probe to determinate water content in organic solvents.XRD,SEM and HRTEM results demonstrate that the obtained PEI-NaBiF_4:Yb~(3+)/Er~(3+) UCNPs are pure hexagonal phase with uniform size.The successful modification of PEI on the UCNPs surface was evidenced by ζ-potential test,XPS and TG analysis.These synthesized UCNPs are disintegrated into smaller nanoparticles in the presence of water and thus result in a surface quenching effect,which show the features of 0-100% wide range water response in various organic solvents.The sensing performance towards real samples was validated by the water content determination in beer,rum and white spirit.Furthermore,the luminescence intensity variation of the PEI-modified NaBiF_4:Yb~(3+)/Er~(3+) enable the test visualization and ease of portability.     

Synthesis and luminescent properties of BaGd2O4:Eu3+ phosphors with highly efficient red-emitting

The BaGd_(2-2 x)Eu_(2 x)O_4(BG, x = 0.01-0.09) phosphors were successfully synthesized via the sol-gel method,and BaY_(2-2 y)Eu_(2 y)O_4(BY, y = 0.005-0.07) phosphors were included for comparison. The pure phase BG phosphors with the ordered CaFe_2 O_4-type structure are obtained by annealing at 1300℃ for5 h. The phosphors with uniform particle size of 120 nm and good dispersion display typical Eu~(3+)emission with the strongest peak at 613 nm(~5 D_0→~7 F_2 transition of Eu3+) under optimal excitation band at 262 nm(CTB band). The presence of Gd~(3+) excitation bands on the PLE spectra monitoring the Eu3+emission directly proves an evidence of Gd~(3+)-Eu~(3+) energy transfer. Owing to the concentration quenching, the optimum content of Eu3+ addition is 5 at%(x = 0.05), and the quenching mechanism is determined to be the exchange reaction between Eu3+. All the BG samples have similar color coordinates and temperature of(0.64 ± 0.02, 0.36 ± 0.01) and 2000 ± 100 K,respectively. The lifetime value of BaGd_(1.9)Eu_(0.1)O_4 for 613 nm is fitted to be 2.19 ± 0.01 ms, and the Eu~(3+) concentration does not change the lifetime significantly. Owing to the Gd~(3+)-Eu~(3+) energy transfer, the luminescent intensity of the BaGd_(1.9)Eu_(0.1)O_4 phosphor is better than BY system. The BG system served as a new type of phosphor is expected to be widely used in lighting and display areas.     

Effect of Li+ ions doping on structure and luminescence of (Y,Gd)BO3:Tb3+

The (Y,Gd)BO3:Tb3+ and Li+-doped (Y,Gd)BO3:Tb3+ phosphors were prepared by high temperature solid-state method. The inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray diffraction (XRD), scanning electron microscopy (SEM), and the excitation and emission spectra were used to characterize the samples. The results of ICP-AES and XRD indicated that Li+ ions could enter the (Y,Gd)BO3:Tb3+ lattice and induce the lattice expansion. It could be seen from SEM that the particles were spherical a...     

Hydrothermal synthesis of SrF2：yb^3＋/Er^3＋ micro-/nanocrystals with multiform morphologies and upconversion properties

Micro-and nanocrystals cubic-phase SrF2:Yb3+/Er3+ upconversion luminescence phosphors were synthesized via a facile hydro-thermal route in the presence of different surfactants.The samples were characterized with X-ray diffraction (XRD),Fourier transform infra-red spectra (FT-IR),scanning electron microscopy (SEM),transmission electron microscopy (TEM),and upconversion emission spectra.As-prepared products showed a variety of morphologies,such as cubic-shaped microcrystal,hierarchical structure microspheres...     

Synthesis and luminescent properties of polycrystalline Gd2(MoO4)3:Dy3+ for white light-emitting diodes

Polycrystalline Gd₂(MoO₄)₃:Dy³⁺ phosphors have been synthesized by high temperature solid-state reaction method. The phosphors were characterized with X-ray diffractometer, thermogravimetric analysis and different scanning calorimeter, scanning electron microscopy, and photoluminescence spectrofluorimeter. Several peaks at 351, 389, 425, 452, and 472 nm appeared in photoluminescence excitation spectrum, which matched well with the emission of the ultraviolet (UV) and blue-light emitting diode (LED) chips. Upon excitation at 389 nm UV light, intense emissions centered at 484, 575 and 668 nm were attributed to the transitions of ⁴F_9/2→⁶H_15/2, ⁴F_9/2→⁶H_13/2 and ⁴F_9/2→⁶H_11/2 of Dy³⁺, respectively. The chromaticity coordinates and correlative color temperatures have been calculated and presented in the Commission International de I'Eclairage (CIE) diagrams. The results indicated that Gd_1.9(MoO₄)₃:Dy_0.1³⁺ with CIE coordinates of (x=0.38, y=0.41) and the correlative color temperature of 4134 K is a potential candidate for white LEDs.