The hyperfine red phosphors,NaEu(MoO4)2,were synthesized by hydrothermal and subsequent heat-treatment processes.The NaEu(MoO4)2 phosphors show regular elliptical morphologies,and the particle sizes of 0.25～0.3 μm.T...The hyperfine red phosphors,NaEu(MoO4)2,were synthesized by hydrothermal and subsequent heat-treatment processes.The NaEu(MoO4)2 phosphors show regular elliptical morphologies,and the particle sizes of 0.25～0.3 μm.The excitation spectra located at short-wavelength UV region belong to the interweave broad charge transfer bands of Mo6+-O2-and Eu3+-O2-,and the three sharp lines around 395 nm,465 nm and 535 nm are ascribed to the Eu3+ 4f excitation transitions.All of the samples can be excited with near-UV 395 nm light and exhibit the characteristic red emission of Eu3+ 5D0→7F2transition.The relative red emission intensities of the optimum phosphors reach two-fold as compared with that of the commercial phosphors.The submicro-phosphors may be applied as red phosphors for white light emitting diodes.展开更多
BaZnP2O7∶Eu3+ phosphor was synthesized by a high temperature solid state reaction.The compound shows four major emission peaks locating at 588,613,622 and 654 nm that correspond to the 5D0-7F1,5D0-7F2 and 5D0-7F3 typ...BaZnP2O7∶Eu3+ phosphor was synthesized by a high temperature solid state reaction.The compound shows four major emission peaks locating at 588,613,622 and 654 nm that correspond to the 5D0-7F1,5D0-7F2 and 5D0-7F3 typical transition of Eu3+,respectively.The influence of the concentration of Eu3+ ions on the emission intensity was investigated and the concentration quench did not occured.The role of charge compensation of Li+,Na+ and Cl-ions to the emission intensity was also studied.It was found that Li+ ions gave the best improvement to enhance the intensity of the emissions.The results show that BaZnP2O7∶Eu3+red-emitting phosphor is very suitable for white light emitting diode(w-LED)based on UV InGaN chip.展开更多
We synthesized NaY(MoO4)2:Eu3+phosphors of different doping concentrations by a molten salt method.This facile way possesses advantages such as simple process,lower calcination temperature(350℃)and small particle siz...We synthesized NaY(MoO4)2:Eu3+phosphors of different doping concentrations by a molten salt method.This facile way possesses advantages such as simple process,lower calcination temperature(350℃)and small particle size(70 nm).The crystal system is tetragonal phase and crystal lattice is body centered.The photo luminescence measurements including emission spectra,excitation spectra and fluorescence decay curves were carried out,elucidating that NaY(MoO4)2:Eu3+can be effectively excited by near UV and blue light.Moreover,it can be concluded that Eu3+energy transfer type is exchange interaction.Huang-Rhys factor and the critical energy transfer distance(Rc)were calculated to be 0.043 and 0.995 nm,respectively.Auzel’s model was used to obtain the intrinsic radiative transition lifetime of5 D0 level(τ0=0.923 ms).Furthermore,a calculation method was used to calculate refractive index n of nontransparent NaY(MoO4)2:1 mol%Eu3+phosphor,and n was obtained to be 1.86.展开更多
A simple co-precipitation approach taking place between Ln3＋, Sr2＋ cations and F anions, led to the formation of nanocrystalline Eu3＋ doped Sr2LnF7 （Ln-La and Gd） complex fluorides. The reaction was carried out i...A simple co-precipitation approach taking place between Ln3＋, Sr2＋ cations and F anions, led to the formation of nanocrystalline Eu3＋ doped Sr2LnF7 （Ln-La and Gd） complex fluorides. The reaction was carried out in the presence of polyeth- ylene glycol, PEG 6000 as a surfactant/surface modifier, providing small size and homogeneity of the products. The synthesized compounds were composed of small nanoparticles with an average size of 15 nm. All obtained Eu3＋ doped compounds exhibited an intensive red luminescence. In the case of gadolinium based compounds, the energy transfer phenomena could be observed from Gd3＋ ions to Eu3＋ ions. In order to study the structure and morphology of the synthesized fluorides, powder X-ray diffraction （XRD） and transmission electron microscopy （TEM） measurements were performed. Also FT-IR spectra of the products were re- corded, revealing the presence of PEG molecules on the nanoparticles suN＇ace. A spectrofluorometry technique was applied to examine optical properties of the synthesized nanoparticles. Excitation and emission spectra as well as luminescence decay curves were measured and analysed. The performed analysis revealed a red luminescence, typical for the Eu3＋ ion situated in the inorganic, highly symmetric matrix. Concentration quenching phenomena and lifetimes shortening, together with an increasing of the Eu3＋ doping level, were observed and discussed. Judd-Ofelt analysis was also performed for all doped samples, in order to support the registered spectroscopic data and examine in details structural and optoelectronic properties of the synthesized nanomaterials.展开更多
ZnTiO3：Eu3＋ phosphors were synthesized with different concentrations of Eu3＋ doping through sol-gel method. The samples were calcined at different temperatures for 2 h in air. The synthesized powders were character...ZnTiO3：Eu3＋ phosphors were synthesized with different concentrations of Eu3＋ doping through sol-gel method. The samples were calcined at different temperatures for 2 h in air. The synthesized powders were characterized by X-ray diffraction（XRD）, scanning electron microscopy-energy dispersive spectroscopy（SEM-EDS）, transmission electron microscopy（TEM）, Raman and photoluminescence spectroscopy. The XRD results showed that the Zn Ti O3：Eu3＋ phosphors doped with different concentrations of Eu3＋ ions calcined at 600 oC were of single phase, which indicated that the Eu3＋ ions had been successfully incorporated into the Zn Ti O3 host lattice and did not destroy the lattice structure of Zn Ti O3 host. The Raman spectrum, SEM and TEM also proved that the doping of Eu3＋ did not change the lattice structure of hexagonal Zn Ti O3 host. The photoluminescence（PL） of Eu3＋ ions with the main emission peak at 614 nm was observed to increase with Eu3＋ concentrations from 0.5 mol.% to 2.0 mol.% and decreased when the concentration was increased to 2.5 mol.%. The decrease in the PL intensity at higher Eu3＋ concentrations could be associated with concentration quenching effect. The CIE1931 chromaticity diagram（x, y） of Zn Ti O3：2.0 wt.%Eu3＋ phosphors were located in the red region（x=0.652, y=0.347）. The luminescence properties suggested that Zn Ti O3：Eu3＋ phosphors might be regarded as a potential red phosphor candidate for light emitting diodes（LEDs）.展开更多
采用化学共沉淀法制备了荧光粉Ca Mo O4:Tb3+、Ca Mo O4:Eu3+,Tb3+,并对其发光性质进行了研究.Ca Mo O4:Tb3+样品在488nm激发下能发出很强的绿光,此时Tb3+的最佳掺杂浓度为15%;在Eu3+和Tb3+共同掺杂的体系中,可以观察到由于Tb3+向Eu3+...采用化学共沉淀法制备了荧光粉Ca Mo O4:Tb3+、Ca Mo O4:Eu3+,Tb3+,并对其发光性质进行了研究.Ca Mo O4:Tb3+样品在488nm激发下能发出很强的绿光,此时Tb3+的最佳掺杂浓度为15%;在Eu3+和Tb3+共同掺杂的体系中,可以观察到由于Tb3+向Eu3+的能量传递使Tb3+敏化Eu3+的发光现象.该荧光粉在近紫外光(379nm)激发下发出较强的白色荧光,光谱测试显示Ca Mo O4:Eu3+,Tb3+的发射光谱存在三个激发峰,分别位于488、543和613 nm处,能够合成较理想的白光.展开更多
文摘The hyperfine red phosphors,NaEu(MoO4)2,were synthesized by hydrothermal and subsequent heat-treatment processes.The NaEu(MoO4)2 phosphors show regular elliptical morphologies,and the particle sizes of 0.25～0.3 μm.The excitation spectra located at short-wavelength UV region belong to the interweave broad charge transfer bands of Mo6+-O2-and Eu3+-O2-,and the three sharp lines around 395 nm,465 nm and 535 nm are ascribed to the Eu3+ 4f excitation transitions.All of the samples can be excited with near-UV 395 nm light and exhibit the characteristic red emission of Eu3+ 5D0→7F2transition.The relative red emission intensities of the optimum phosphors reach two-fold as compared with that of the commercial phosphors.The submicro-phosphors may be applied as red phosphors for white light emitting diodes.
文摘BaZnP2O7∶Eu3+ phosphor was synthesized by a high temperature solid state reaction.The compound shows four major emission peaks locating at 588,613,622 and 654 nm that correspond to the 5D0-7F1,5D0-7F2 and 5D0-7F3 typical transition of Eu3+,respectively.The influence of the concentration of Eu3+ ions on the emission intensity was investigated and the concentration quench did not occured.The role of charge compensation of Li+,Na+ and Cl-ions to the emission intensity was also studied.It was found that Li+ ions gave the best improvement to enhance the intensity of the emissions.The results show that BaZnP2O7∶Eu3+red-emitting phosphor is very suitable for white light emitting diode(w-LED)based on UV InGaN chip.
基金Project supported by the National Natural Science Foundation of China(51002041)
文摘We synthesized NaY(MoO4)2:Eu3+phosphors of different doping concentrations by a molten salt method.This facile way possesses advantages such as simple process,lower calcination temperature(350℃)and small particle size(70 nm).The crystal system is tetragonal phase and crystal lattice is body centered.The photo luminescence measurements including emission spectra,excitation spectra and fluorescence decay curves were carried out,elucidating that NaY(MoO4)2:Eu3+can be effectively excited by near UV and blue light.Moreover,it can be concluded that Eu3+energy transfer type is exchange interaction.Huang-Rhys factor and the critical energy transfer distance(Rc)were calculated to be 0.043 and 0.995 nm,respectively.Auzel’s model was used to obtain the intrinsic radiative transition lifetime of5 D0 level(τ0=0.923 ms).Furthermore,a calculation method was used to calculate refractive index n of nontransparent NaY(MoO4)2:1 mol%Eu3+phosphor,and n was obtained to be 1.86.
基金Project supported by Polish Ministry of Science and Higher Education(Diamond Grant"Nr DI2011 011441)
文摘A simple co-precipitation approach taking place between Ln3＋, Sr2＋ cations and F anions, led to the formation of nanocrystalline Eu3＋ doped Sr2LnF7 （Ln-La and Gd） complex fluorides. The reaction was carried out in the presence of polyeth- ylene glycol, PEG 6000 as a surfactant/surface modifier, providing small size and homogeneity of the products. The synthesized compounds were composed of small nanoparticles with an average size of 15 nm. All obtained Eu3＋ doped compounds exhibited an intensive red luminescence. In the case of gadolinium based compounds, the energy transfer phenomena could be observed from Gd3＋ ions to Eu3＋ ions. In order to study the structure and morphology of the synthesized fluorides, powder X-ray diffraction （XRD） and transmission electron microscopy （TEM） measurements were performed. Also FT-IR spectra of the products were re- corded, revealing the presence of PEG molecules on the nanoparticles suN＇ace. A spectrofluorometry technique was applied to examine optical properties of the synthesized nanoparticles. Excitation and emission spectra as well as luminescence decay curves were measured and analysed. The performed analysis revealed a red luminescence, typical for the Eu3＋ ion situated in the inorganic, highly symmetric matrix. Concentration quenching phenomena and lifetimes shortening, together with an increasing of the Eu3＋ doping level, were observed and discussed. Judd-Ofelt analysis was also performed for all doped samples, in order to support the registered spectroscopic data and examine in details structural and optoelectronic properties of the synthesized nanomaterials.
基金Project supported by Natural Science Foundation of the Jiangsu Higher Education Institutions of China(12KJA430006,13KJB430024)
文摘ZnTiO3：Eu3＋ phosphors were synthesized with different concentrations of Eu3＋ doping through sol-gel method. The samples were calcined at different temperatures for 2 h in air. The synthesized powders were characterized by X-ray diffraction（XRD）, scanning electron microscopy-energy dispersive spectroscopy（SEM-EDS）, transmission electron microscopy（TEM）, Raman and photoluminescence spectroscopy. The XRD results showed that the Zn Ti O3：Eu3＋ phosphors doped with different concentrations of Eu3＋ ions calcined at 600 oC were of single phase, which indicated that the Eu3＋ ions had been successfully incorporated into the Zn Ti O3 host lattice and did not destroy the lattice structure of Zn Ti O3 host. The Raman spectrum, SEM and TEM also proved that the doping of Eu3＋ did not change the lattice structure of hexagonal Zn Ti O3 host. The photoluminescence（PL） of Eu3＋ ions with the main emission peak at 614 nm was observed to increase with Eu3＋ concentrations from 0.5 mol.% to 2.0 mol.% and decreased when the concentration was increased to 2.5 mol.%. The decrease in the PL intensity at higher Eu3＋ concentrations could be associated with concentration quenching effect. The CIE1931 chromaticity diagram（x, y） of Zn Ti O3：2.0 wt.%Eu3＋ phosphors were located in the red region（x=0.652, y=0.347）. The luminescence properties suggested that Zn Ti O3：Eu3＋ phosphors might be regarded as a potential red phosphor candidate for light emitting diodes（LEDs）.
文摘采用化学共沉淀法制备了荧光粉Ca Mo O4:Tb3+、Ca Mo O4:Eu3+,Tb3+,并对其发光性质进行了研究.Ca Mo O4:Tb3+样品在488nm激发下能发出很强的绿光,此时Tb3+的最佳掺杂浓度为15%;在Eu3+和Tb3+共同掺杂的体系中,可以观察到由于Tb3+向Eu3+的能量传递使Tb3+敏化Eu3+的发光现象.该荧光粉在近紫外光(379nm)激发下发出较强的白色荧光,光谱测试显示Ca Mo O4:Eu3+,Tb3+的发射光谱存在三个激发峰,分别位于488、543和613 nm处,能够合成较理想的白光.
