The europium-doped LaF3 nanoparticles were prepared by refluxing method in glycerol/water mixture and characterized with X-ray diffraction（XRD）, field emission scanning electron microscopy（FE-SEM）, UV-vis diffuse ...The europium-doped LaF3 nanoparticles were prepared by refluxing method in glycerol/water mixture and characterized with X-ray diffraction（XRD）, field emission scanning electron microscopy（FE-SEM）, UV-vis diffuse reflectance spectrum, and photoluminescence spectra.The results of XRD indicated that the obtained LaF3：Eu^3＋ nanoparticles were well crystallized with a hexagonal structure.The FE-SEM image illustrated that the LaF3：Eu^3＋ nanoparticles were spherical with an average size around 30 nm.Under irradiation of UV light, the emission spectrum of LaF3：Eu^3＋ nanoparticles exhibited the characteristic line emissions arising from the 5D0→7FJ（J=1, 2, 3, 4） transitions of the Eu3＋ ions, with the dominating emission centered at 590 nm.In addition, the emissions from the 5D1 level could be clearly observed due to the low phonon energies（-350 cm^-1） of LaF3 matrix.The optimum doping concentration for LaF3：Eu3＋ nanoparticles was determined to be 20mol.%.展开更多
A series of(Y_(1-y), Gdy)_(0.95-x)(P_y, V_(1-y))O_4 :0.05Eu^(3+), xBi^(3+)+phosphors have been successfully prepared by a subsection method. The crystal structure, surface morphology and luminescence properties were i...A series of(Y_(1-y), Gdy)_(0.95-x)(P_y, V_(1-y))O_4 :0.05Eu^(3+), xBi^(3+)+phosphors have been successfully prepared by a subsection method. The crystal structure, surface morphology and luminescence properties were investigated. It was found that the sintered samples crystallized in a tetragonal crystal system with space group I_(41)/amd(a = b = 0.7119 nm, c = 0.6290 nm). The products presented rod-like morphology with length of 100-150 nm and width of 50-100 nm. A maximum peak at 619 nm(~5D_0 →~7F_2) was observed in emission spectrum of the phosphors. It was also found that co-doping of Bi^(3+)+, P5+and Gd^(3+)ions into YVO_4:Eu^(3+)can not only made the right edge of the excitation band shift to the long-wavelength region, but also increased the emission intensity at 619 nm sharply and decreased the lifetime of fluorescence decay. These results may expand the application scope of the phosphors.展开更多
Ca（NO3）2·4H2O, Eu（NO3）3 and H2C2O4·2H2O were adopted to synthesize CaO： Eu3＋ with the chemical co-precipitation method, and the effects of the calcination temperature and Eu3＋ doping concentration on ...Ca（NO3）2·4H2O, Eu（NO3）3 and H2C2O4·2H2O were adopted to synthesize CaO： Eu3＋ with the chemical co-precipitation method, and the effects of the calcination temperature and Eu3＋ doping concentration on the phosphor structure and its luminescent properties were investigated by TG-SDTA, XRD, and PL-PLE. The results confirm that the Eu3＋ ions as luminescent centers substi-tutes Ca2＋ sites without changing the crystal structure of cubic CaO. The optimum calcination tem-perature and the optimum concentration of Eu3＋ are 1 100 ℃ and 1 mol%, respectively, under which the best crystallinity and highest PL intensity appeared. The maximum emission wavelength is 592 nm （5D0→7F1） which is excited by xenon lamp with the wavelength of 200-280 nm, indicating that the Eu3＋ ion mainly locates in the symmetric position （Oh） in the crystal lattice of CaO.展开更多
The Eu^3＋ activated Lu2MoO6 phosphors were synthesized by high-temperature solid-state reaction method. The X-ray diffraction （XRD）, excitation spectra, emission spectra and decay lifetime of the phosphors were me...The Eu^3＋ activated Lu2MoO6 phosphors were synthesized by high-temperature solid-state reaction method. The X-ray diffraction （XRD）, excitation spectra, emission spectra and decay lifetime of the phosphors were measured to characterize the structure and luminescent properties. The XRD results show that all the prepared phosphors can be assigned to the monoclinic structure. The experimental results indicate efficient absorption of near ultraviolet light from the Mo^6＋O^2- group followed by intensive emission in the visible spectral range. The optimal content of Eu3＋ is 10% （mole fraction）. The critical distance Rc and energy transfer mechanism were also discussed in detail. This red emitting material may be applied as a promising red phosphor for the near ultraviolet excited white light emitting diodes.展开更多
The luminescent properties of Eu^3＋doped Ca2SiO4 red phosphors synthesized by the flux fusion reaction method were investigated. It was found that the excitation spectrum included two regions： the weak excitation ba...The luminescent properties of Eu^3＋doped Ca2SiO4 red phosphors synthesized by the flux fusion reaction method were investigated. It was found that the excitation spectrum included two regions： the weak excitation band below 325 nm and strong narrow peaks above 325 nm. The main peak of the excitation band was located at 400 nm. The peaks located at 290 nm were assigned to the combination of the charge transfer transition of O-Eu, peaks above 325 nm （325, 385, 400, 470, 511, and 539 nm） were assigned to the f-f transitions of Eu^3＋. The emission spectrum was dominated by the red peak located at 612 nm due to the electric dipole transition of ^5D0-^7F2. In addition, the effects of the Eu^3＋ content and charge compensators of Li^＋, Na^＋, K^＋, and Cl^- ions on the emission intensity were investigated. The experiment results suggested that the strongest emission was obtained when the concentration of the Eu^3＋ ions was 0.3 mol^-1, and Li^＋ ions gave the best improvement to enhance the emission intensity. Ca2SiO4：Eu^3＋, Li^＋ was thus suitable for low-cost trichromatic white light emitting diodes （WLED） based on UV InGaN chip.展开更多
Nanocrystalline Gd3Ga5O12:Eu3+ with cubic phase was prepared by a urea homogeneous precipitation method. X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), Fourier transform infrared spectrosc...Nanocrystalline Gd3Ga5O12:Eu3+ with cubic phase was prepared by a urea homogeneous precipitation method. X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric and differential thermal analysis (TG-DTA) and photoluminescence spectra were used to characterize the samples. The effects of the initial solution pH value and urea content on the structure of the sample were studied. The XRD results show that pure phase Gd3Ga5O12 can be obtained at pH =6 and pH =8 of the initial solution. The average crystallite size can be calculated as in the range of 24~33 nm. The average crystallite size decreases with increasing molar ratio of urea to metal ion. The results of excitation spectra and emission spectra show that the emission peaks are ascribed to 5D0→7FJ transitions of Eu3+, and the magnetic dipole transition originated from 5D0 →7F1 of Eu3+ is the strongest; the broad excitation bands belong to change transfer band of Eu?O and the host absorption of Gd3Ga5O12. An efficient energy transfer occurs from Gd3+ to Eu3+.展开更多
The CaS∶Eu^(2+), Sm^(3+) powders were prepared by high-temperature solid method in a reducing atmosphere. The influences of temperature and fired-time on properties of samples were studied. XRD analysis shows that cr...The CaS∶Eu^(2+), Sm^(3+) powders were prepared by high-temperature solid method in a reducing atmosphere. The influences of temperature and fired-time on properties of samples were studied. XRD analysis shows that crystal structure of CaS has formed at 700 ℃. Spectrum analysis results show that the samples which were stimulated by 980 nm laser after excited by ultraviolet lamp emit red luminescence peaking at 649 nm.展开更多
Eu^3＋-doped Gd2Mo3O9 was prepared by solid-state reaction method using Na2CO3 as flux and characterized by powder X-ray diffractometry. According to X-ray diffraction, this material belonged to a tetragonal system wi...Eu^3＋-doped Gd2Mo3O9 was prepared by solid-state reaction method using Na2CO3 as flux and characterized by powder X-ray diffractometry. According to X-ray diffraction, this material belonged to a tetragonal system with space group I41/α. The effects of flux content and sintering temperature on the luminescent properties were investigated with the emission and excitation spectra. The results showed that flux content and sintering temperature had effects on the luminescent properties, the optimized flux content and the best temperature was 3 % and 800 ℃ respectively. The excitation and emission spectra also showed that this phosphor could be effectively excited by C-T band （280 nm）, ultraviolet light 395 nm and blue light 465 nm. The wavelengths at 395 and 465 nm were nicely fitting in with the widely applied output wavelengths of ultraviolet or blue LED chips. Integrated emission intensity of Gd2Mo3O9 ： Eu was twice higher than that of Y2O2S ： Eu^3 ＋ under 395 nm excitation. The Eu^3＋ doped Gd2Mo309 phosphor may be a better candidate in solid-state lighting applications.展开更多
YAl3 （BO3）4： Eu^3＋ phosphors were prepared by the conventional solid state reaction. The phase structure and morphology were investigated by X-ray diffraction （XRD） and scanning electron microscope （SEM）. Dopi...YAl3 （BO3）4： Eu^3＋ phosphors were prepared by the conventional solid state reaction. The phase structure and morphology were investigated by X-ray diffraction （XRD） and scanning electron microscope （SEM）. Doping YAl3（BO3）4： Eu^3＋ phosphors with concentration of Eu^3＋ ions of 0, 2, 5, 8 and 10 mol% were studied and their luminescent properties at room temperature were discussed. The excitation spectrum of Y0.95Eu0.05Al3（BO3）4 was composed of a broad band centered at about 252 nm and a group of lines in the longer wavelength region. In the emission spectra, the peak wavelength was about 614 nm under a 252 nm UV excitation. The optimal doping concentration of Eu^3＋ ions in YAl3（BO3）4： Eu^3＋ phosphors was 8 mol%.展开更多
In this paper, the Sr3Y2 （BO3）4 ：Eu^3＋ phosphor was synthesized by high temperature solid-state reaction method and the luminescence characteristics were investigated. The emission spectrum exhibits one strong red...In this paper, the Sr3Y2 （BO3）4 ：Eu^3＋ phosphor was synthesized by high temperature solid-state reaction method and the luminescence characteristics were investigated. The emission spectrum exhibits one strong red emission at 613 nm corresponding to the electric dipole 5^Do-7^F2 transition of Eu^3＋ under 365 nm excitation, this is because Eu^3＋ substituted for Y^3＋ occupied the non-centrosymmetric position in the crystal structure of Sr3Y2（BO3）4. The excitation spectrum indicates that the phosphor can be effectively excited by ultraviolet （254 nm, 365 nm and 400 nm） and blue （470 nm） light. The effect of Eu^3＋ concentration on the red emission of Sr3Y2（BO3）4 ：Eu^3＋ was measured, the result shows that the emission intensities increase with increasing Eu^3＋ concentration, then decrease. The Commission Internationale del＇Eclairage chromaticity （x, y） of Sr3Y2（BO3）4 ：Eu^3＋ phosphor is （0.640, 0.355） at 15 mol% Eu^3＋.展开更多
γ-LiAlO2：Eu3＋（Eu3＋：LAO） phosphor was obtained by gel combustion method using LiNO3,Al（NO3）3·9H2O,Eu（NO3）3·6H2O and citric acid as raw materials.The structure,morphology and luminescence were chara...γ-LiAlO2：Eu3＋（Eu3＋：LAO） phosphor was obtained by gel combustion method using LiNO3,Al（NO3）3·9H2O,Eu（NO3）3·6H2O and citric acid as raw materials.The structure,morphology and luminescence were characterized by means of X-ray diffraction （XRD）,scanning electron microscopy （SEM）,photoluminescence （PL）.The results demonstrated that the phosphor was pure-phase of flaky tetragonal crystal system with a mean size of around 1 μm.The strongest excitation peak was at 254 nm,belonging to the broadband excitation and the maximum emission peak was at 613 nm,corresponding to the 5D0→7F2 transition of Eu3＋.Luminous intensity is closely related to the calcination temperature and doping concentration of Eu3＋.展开更多
Gd 2O 3∶Eu 3+ phosphors were prepared by urea homogeneous precipitation with different surfactant and sol-gel method. XRD patterns show that all the obtained samples are in cubic Gd 2O 3, and the results of FTIR...Gd 2O 3∶Eu 3+ phosphors were prepared by urea homogeneous precipitation with different surfactant and sol-gel method. XRD patterns show that all the obtained samples are in cubic Gd 2O 3, and the results of FTIR and fluorescent spectra conformed that OP is a good surfactant for preparing the Gd 2O 3∶Eu 3+ phosphors. The SEM photographs show that the particles prepared by urea homogeneous precipitation method are all spherical and well-dispersed, and grain morphology can be controlled by different surfactant. XRD and SEM indicate that the particle sizes prepared by sol-gel method are in the range of 5～30 nm, and the grain sizes increase with increasing of heated temperatures. Luminescence spectra indicat that the main emission peaks of all samples are at 610 nm, the intensities are different from samples prepared with different surfactant and the luminescence intensities increase with increasing of annealed temperatures.展开更多
New long phosphorescent phosphors Ba 1-xCa xAl 2O 4∶Eu 2+, Dy 3+ with tunable color emission were prepared and studied. The emission spectra show that the tuning range of the color emission of the phosphors i...New long phosphorescent phosphors Ba 1-xCa xAl 2O 4∶Eu 2+, Dy 3+ with tunable color emission were prepared and studied. The emission spectra show that the tuning range of the color emission of the phosphors is between 498 and 440 nm, which is dependent on x, under the excitation of UV. The wavelength of the afterglow increases with the increasing of x until x equals 0.6. The XRD patterns show that the single phase limit in the phosphors is below x value of 0 4. The Thermoluminescence spectra were measured to investigate the traps created by the doping of Dy 3+.展开更多
We discuss the influence of Al^3＋ on the charge transfer state （CTS） and the photoluminescence properties of BaZr（BO3）2：Eu. The results reveal that there is a red shift which is about 20nm for the charge transfe...We discuss the influence of Al^3＋ on the charge transfer state （CTS） and the photoluminescence properties of BaZr（BO3）2：Eu. The results reveal that there is a red shift which is about 20nm for the charge transfer state when doping with Al^3＋ and indicate the formation of ‘free＇ electrons due to the change of microstructures. In addition, the influence or Al^3＋ doping on the PPR is analysed and a new explanation is raised based on the photo luminescent mechanism. It is the CTS intensity rather than the CTS energy that influences the peak-peak ratio.展开更多
The vibrational spectrum of the CaAl2B2O7 was investigated. It was shown that the vibrations of the BO3 groups are present in the region of 1400600 cm-1, and the bands at 519 nm-1 may originate from the AlO6 vibration...The vibrational spectrum of the CaAl2B2O7 was investigated. It was shown that the vibrations of the BO3 groups are present in the region of 1400600 cm-1, and the bands at 519 nm-1 may originate from the AlO6 vibration. The luminescence properties of Eu3+ in CaAl2B2O7 were investigated. It was found that the Eu3+ ion in CaAl2B2O7 occupies two different sites. Investigation on the phonon sideband of Eu3+ indicates that BO3 groups are present in the surroundings of Eu3+ ions.展开更多
The Eu3＋-doped La2Zr207 phosphor with rod-like morphology was successfully synthesized by conventional solid state reaction and hydrothermal method. X-ray diffraction patterns, transmission electron microscopy, and p...The Eu3＋-doped La2Zr207 phosphor with rod-like morphology was successfully synthesized by conventional solid state reaction and hydrothermal method. X-ray diffraction patterns, transmission electron microscopy, and photoluminescence spectra were employed to charac- terize its structure and morphology as well as luminescent properties. The results indicated that the red-emitting phosphor La2Zr207：Eu3＋ had well crystallized and belonged to the cubic structure with space group of Fd3m. The as-obtained product mainly appeared as straight nanorods with an average diameter of 47 nm and length of 50-700 nm. The pos- sible growth mechanism was also discussed. It was found that under blue excitation with a wavelength of 466 nm, the La2Zr2OT：Eu3＋ phosphor exhibited a characteristic red emission at 616 nm that was attributed to the hypersensitive 5D0--＊TF2 electric dipole transition of Eu3＋ ions. Meanwhile, it was more interesting to note that the emission of 5D1--＊TFj （J=0, 1, 2） transitions and the splitting patterns of 5D0---＋TFJ （J--l, 2, 4） transitions of Eu3＋ ions can be observed in the luminescent spectra of La2Zr207：Eu3＋. It was demonstrated that Eu3＋ preferred to occupy a low symmetry site.展开更多
基金supported by the Natural Science Foundation of Henan Province (082300440130, 2008A180039, 2007150049)Startup Fund for Doctoral Program of Zhoukou Normal University
文摘The europium-doped LaF3 nanoparticles were prepared by refluxing method in glycerol/water mixture and characterized with X-ray diffraction（XRD）, field emission scanning electron microscopy（FE-SEM）, UV-vis diffuse reflectance spectrum, and photoluminescence spectra.The results of XRD indicated that the obtained LaF3：Eu^3＋ nanoparticles were well crystallized with a hexagonal structure.The FE-SEM image illustrated that the LaF3：Eu^3＋ nanoparticles were spherical with an average size around 30 nm.Under irradiation of UV light, the emission spectrum of LaF3：Eu^3＋ nanoparticles exhibited the characteristic line emissions arising from the 5D0→7FJ（J=1, 2, 3, 4） transitions of the Eu3＋ ions, with the dominating emission centered at 590 nm.In addition, the emissions from the 5D1 level could be clearly observed due to the low phonon energies（-350 cm^-1） of LaF3 matrix.The optimum doping concentration for LaF3：Eu3＋ nanoparticles was determined to be 20mol.%.
基金supported by the Program for New Material Development & Application innovative Research Team of Higher Education in Chong Qing of China (Grant No. 201042)
文摘A series of(Y_(1-y), Gdy)_(0.95-x)(P_y, V_(1-y))O_4 :0.05Eu^(3+), xBi^(3+)+phosphors have been successfully prepared by a subsection method. The crystal structure, surface morphology and luminescence properties were investigated. It was found that the sintered samples crystallized in a tetragonal crystal system with space group I_(41)/amd(a = b = 0.7119 nm, c = 0.6290 nm). The products presented rod-like morphology with length of 100-150 nm and width of 50-100 nm. A maximum peak at 619 nm(~5D_0 →~7F_2) was observed in emission spectrum of the phosphors. It was also found that co-doping of Bi^(3+)+, P5+and Gd^(3+)ions into YVO_4:Eu^(3+)can not only made the right edge of the excitation band shift to the long-wavelength region, but also increased the emission intensity at 619 nm sharply and decreased the lifetime of fluorescence decay. These results may expand the application scope of the phosphors.
基金Funded by the Science and Technology Bureau of Sichun Province(No.2006J13-059)Education Bureau of Sichun Province (No. 2006A094)
文摘Ca（NO3）2·4H2O, Eu（NO3）3 and H2C2O4·2H2O were adopted to synthesize CaO： Eu3＋ with the chemical co-precipitation method, and the effects of the calcination temperature and Eu3＋ doping concentration on the phosphor structure and its luminescent properties were investigated by TG-SDTA, XRD, and PL-PLE. The results confirm that the Eu3＋ ions as luminescent centers substi-tutes Ca2＋ sites without changing the crystal structure of cubic CaO. The optimum calcination tem-perature and the optimum concentration of Eu3＋ are 1 100 ℃ and 1 mol%, respectively, under which the best crystallinity and highest PL intensity appeared. The maximum emission wavelength is 592 nm （5D0→7F1） which is excited by xenon lamp with the wavelength of 200-280 nm, indicating that the Eu3＋ ion mainly locates in the symmetric position （Oh） in the crystal lattice of CaO.
基金Project(11404047)supported by the National Natural Science Foundation of ChinaProjects(CSTC2015jcyj A50005,CSTC2014JCYJA50034)supported by the Natural Science Foundation Project of Chongqing,ChinaProject(KJ1500412,KJ1500409)supported by Scientific and Technological Research Program of Chongqing Municipal Education Commission,China
文摘The Eu^3＋ activated Lu2MoO6 phosphors were synthesized by high-temperature solid-state reaction method. The X-ray diffraction （XRD）, excitation spectra, emission spectra and decay lifetime of the phosphors were measured to characterize the structure and luminescent properties. The XRD results show that all the prepared phosphors can be assigned to the monoclinic structure. The experimental results indicate efficient absorption of near ultraviolet light from the Mo^6＋O^2- group followed by intensive emission in the visible spectral range. The optimal content of Eu3＋ is 10% （mole fraction）. The critical distance Rc and energy transfer mechanism were also discussed in detail. This red emitting material may be applied as a promising red phosphor for the near ultraviolet excited white light emitting diodes.
基金supported by Jiangxi Provincial Department of Education (GJJ08344)
文摘The luminescent properties of Eu^3＋doped Ca2SiO4 red phosphors synthesized by the flux fusion reaction method were investigated. It was found that the excitation spectrum included two regions： the weak excitation band below 325 nm and strong narrow peaks above 325 nm. The main peak of the excitation band was located at 400 nm. The peaks located at 290 nm were assigned to the combination of the charge transfer transition of O-Eu, peaks above 325 nm （325, 385, 400, 470, 511, and 539 nm） were assigned to the f-f transitions of Eu^3＋. The emission spectrum was dominated by the red peak located at 612 nm due to the electric dipole transition of ^5D0-^7F2. In addition, the effects of the Eu^3＋ content and charge compensators of Li^＋, Na^＋, K^＋, and Cl^- ions on the emission intensity were investigated. The experiment results suggested that the strongest emission was obtained when the concentration of the Eu^3＋ ions was 0.3 mol^-1, and Li^＋ ions gave the best improvement to enhance the emission intensity. Ca2SiO4：Eu^3＋, Li^＋ was thus suitable for low-cost trichromatic white light emitting diodes （WLED） based on UV InGaN chip.
基金financially supported by the Science and Technology Research Project of Department of Education of Liaoning Province,China(No.L2011063)
文摘Nanocrystalline Gd3Ga5O12:Eu3+ with cubic phase was prepared by a urea homogeneous precipitation method. X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric and differential thermal analysis (TG-DTA) and photoluminescence spectra were used to characterize the samples. The effects of the initial solution pH value and urea content on the structure of the sample were studied. The XRD results show that pure phase Gd3Ga5O12 can be obtained at pH =6 and pH =8 of the initial solution. The average crystallite size can be calculated as in the range of 24~33 nm. The average crystallite size decreases with increasing molar ratio of urea to metal ion. The results of excitation spectra and emission spectra show that the emission peaks are ascribed to 5D0→7FJ transitions of Eu3+, and the magnetic dipole transition originated from 5D0 →7F1 of Eu3+ is the strongest; the broad excitation bands belong to change transfer band of Eu?O and the host absorption of Gd3Ga5O12. An efficient energy transfer occurs from Gd3+ to Eu3+.
文摘The CaS∶Eu^(2+), Sm^(3+) powders were prepared by high-temperature solid method in a reducing atmosphere. The influences of temperature and fired-time on properties of samples were studied. XRD analysis shows that crystal structure of CaS has formed at 700 ℃. Spectrum analysis results show that the samples which were stimulated by 980 nm laser after excited by ultraviolet lamp emit red luminescence peaking at 649 nm.
基金Project supported by the National Natural Science Foundation of China (50572102, 50502031) Natural Science Foundation of Jilin Province (1999514, 2003051422) Outstanding Young People Foundation of Jilin Province (20040113)
文摘Eu^3＋-doped Gd2Mo3O9 was prepared by solid-state reaction method using Na2CO3 as flux and characterized by powder X-ray diffractometry. According to X-ray diffraction, this material belonged to a tetragonal system with space group I41/α. The effects of flux content and sintering temperature on the luminescent properties were investigated with the emission and excitation spectra. The results showed that flux content and sintering temperature had effects on the luminescent properties, the optimized flux content and the best temperature was 3 % and 800 ℃ respectively. The excitation and emission spectra also showed that this phosphor could be effectively excited by C-T band （280 nm）, ultraviolet light 395 nm and blue light 465 nm. The wavelengths at 395 and 465 nm were nicely fitting in with the widely applied output wavelengths of ultraviolet or blue LED chips. Integrated emission intensity of Gd2Mo3O9 ： Eu was twice higher than that of Y2O2S ： Eu^3 ＋ under 395 nm excitation. The Eu^3＋ doped Gd2Mo309 phosphor may be a better candidate in solid-state lighting applications.
文摘YAl3 （BO3）4： Eu^3＋ phosphors were prepared by the conventional solid state reaction. The phase structure and morphology were investigated by X-ray diffraction （XRD） and scanning electron microscope （SEM）. Doping YAl3（BO3）4： Eu^3＋ phosphors with concentration of Eu^3＋ ions of 0, 2, 5, 8 and 10 mol% were studied and their luminescent properties at room temperature were discussed. The excitation spectrum of Y0.95Eu0.05Al3（BO3）4 was composed of a broad band centered at about 252 nm and a group of lines in the longer wavelength region. In the emission spectra, the peak wavelength was about 614 nm under a 252 nm UV excitation. The optimal doping concentration of Eu^3＋ ions in YAl3（BO3）4： Eu^3＋ phosphors was 8 mol%.
基金supported by Hebei Provincial Technology Development Foundation of China (Grant No 51215103b)Science Foundation of Hebei University, China (Grant No 2006Q06)
文摘In this paper, the Sr3Y2 （BO3）4 ：Eu^3＋ phosphor was synthesized by high temperature solid-state reaction method and the luminescence characteristics were investigated. The emission spectrum exhibits one strong red emission at 613 nm corresponding to the electric dipole 5^Do-7^F2 transition of Eu^3＋ under 365 nm excitation, this is because Eu^3＋ substituted for Y^3＋ occupied the non-centrosymmetric position in the crystal structure of Sr3Y2（BO3）4. The excitation spectrum indicates that the phosphor can be effectively excited by ultraviolet （254 nm, 365 nm and 400 nm） and blue （470 nm） light. The effect of Eu^3＋ concentration on the red emission of Sr3Y2（BO3）4 ：Eu^3＋ was measured, the result shows that the emission intensities increase with increasing Eu^3＋ concentration, then decrease. The Commission Internationale del＇Eclairage chromaticity （x, y） of Sr3Y2（BO3）4 ：Eu^3＋ phosphor is （0.640, 0.355） at 15 mol% Eu^3＋.
基金Funded by Southwest University of Technology (No.08zx0103)
文摘γ-LiAlO2：Eu3＋（Eu3＋：LAO） phosphor was obtained by gel combustion method using LiNO3,Al（NO3）3·9H2O,Eu（NO3）3·6H2O and citric acid as raw materials.The structure,morphology and luminescence were characterized by means of X-ray diffraction （XRD）,scanning electron microscopy （SEM）,photoluminescence （PL）.The results demonstrated that the phosphor was pure-phase of flaky tetragonal crystal system with a mean size of around 1 μm.The strongest excitation peak was at 254 nm,belonging to the broadband excitation and the maximum emission peak was at 613 nm,corresponding to the 5D0→7F2 transition of Eu3＋.Luminous intensity is closely related to the calcination temperature and doping concentration of Eu3＋.
文摘Gd 2O 3∶Eu 3+ phosphors were prepared by urea homogeneous precipitation with different surfactant and sol-gel method. XRD patterns show that all the obtained samples are in cubic Gd 2O 3, and the results of FTIR and fluorescent spectra conformed that OP is a good surfactant for preparing the Gd 2O 3∶Eu 3+ phosphors. The SEM photographs show that the particles prepared by urea homogeneous precipitation method are all spherical and well-dispersed, and grain morphology can be controlled by different surfactant. XRD and SEM indicate that the particle sizes prepared by sol-gel method are in the range of 5～30 nm, and the grain sizes increase with increasing of heated temperatures. Luminescence spectra indicat that the main emission peaks of all samples are at 610 nm, the intensities are different from samples prepared with different surfactant and the luminescence intensities increase with increasing of annealed temperatures.
文摘New long phosphorescent phosphors Ba 1-xCa xAl 2O 4∶Eu 2+, Dy 3+ with tunable color emission were prepared and studied. The emission spectra show that the tuning range of the color emission of the phosphors is between 498 and 440 nm, which is dependent on x, under the excitation of UV. The wavelength of the afterglow increases with the increasing of x until x equals 0.6. The XRD patterns show that the single phase limit in the phosphors is below x value of 0 4. The Thermoluminescence spectra were measured to investigate the traps created by the doping of Dy 3+.
基金Supported by the Natural Science Foundation of Tianjin （33601111）, and the Technology Development Foundation of Tianjin University of Technology under Grant No Lg04032.
文摘We discuss the influence of Al^3＋ on the charge transfer state （CTS） and the photoluminescence properties of BaZr（BO3）2：Eu. The results reveal that there is a red shift which is about 20nm for the charge transfer state when doping with Al^3＋ and indicate the formation of ‘free＇ electrons due to the change of microstructures. In addition, the influence or Al^3＋ doping on the PPR is analysed and a new explanation is raised based on the photo luminescent mechanism. It is the CTS intensity rather than the CTS energy that influences the peak-peak ratio.
文摘The vibrational spectrum of the CaAl2B2O7 was investigated. It was shown that the vibrations of the BO3 groups are present in the region of 1400600 cm-1, and the bands at 519 nm-1 may originate from the AlO6 vibration. The luminescence properties of Eu3+ in CaAl2B2O7 were investigated. It was found that the Eu3+ ion in CaAl2B2O7 occupies two different sites. Investigation on the phonon sideband of Eu3+ indicates that BO3 groups are present in the surroundings of Eu3+ ions.
文摘The Eu3＋-doped La2Zr207 phosphor with rod-like morphology was successfully synthesized by conventional solid state reaction and hydrothermal method. X-ray diffraction patterns, transmission electron microscopy, and photoluminescence spectra were employed to charac- terize its structure and morphology as well as luminescent properties. The results indicated that the red-emitting phosphor La2Zr207：Eu3＋ had well crystallized and belonged to the cubic structure with space group of Fd3m. The as-obtained product mainly appeared as straight nanorods with an average diameter of 47 nm and length of 50-700 nm. The pos- sible growth mechanism was also discussed. It was found that under blue excitation with a wavelength of 466 nm, the La2Zr2OT：Eu3＋ phosphor exhibited a characteristic red emission at 616 nm that was attributed to the hypersensitive 5D0--＊TF2 electric dipole transition of Eu3＋ ions. Meanwhile, it was more interesting to note that the emission of 5D1--＊TFj （J=0, 1, 2） transitions and the splitting patterns of 5D0---＋TFJ （J--l, 2, 4） transitions of Eu3＋ ions can be observed in the luminescent spectra of La2Zr207：Eu3＋. It was demonstrated that Eu3＋ preferred to occupy a low symmetry site.
