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1.
Ca2RE8(SiO4)6O2 (RE=Y, Gd, La) is a kind of ternary rare-earth-metal silicate with the oxyapatite structure, which was used as host materials for the luminescence of various rare earth and mercury-like ions. Ca2Gd8(SiO4)6O2:Er3 phosphors were prepared through the sol-gel process. X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicate that the phosphors crystallized completely at 1000 ℃. SEM study reveals that the average grain size is 400~1000 nm. In Ca2Gd8(SiO4)6O2:Er3 phosphors, the Er3 shows its characteristic green emission at 528 nm (2H11/2-4I15/2) and 548 nm(4S3/2-4I15/2) upon excitation into 382 nm, with an optimum doping concentration of 5% (mole fraction) of Gd3 in the host lattices. 相似文献
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Ca2Gd8(SiO4)6O2∶ A(A=Pb2 , Tm3 )phosphors were prepared through the sol-gel process. X-ray diffraction(XRD), scanning electron microscopy(SEM)and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicate that the phosphors crystallized completely at 1000 ℃. SEM study reveals that the average grain size is 300~1000 nm. In Ca2Gd8(SiO4)6O2∶ Tm3 phosphors, the Tm3 shows its characteristic blue emission at 456 nm(1D2-3F4)upon excitation into its 3H6 - 1D2(361 nm), with an optimum doping concentration of 1mol% of Gd3 in the host lattices. In Ca2Gd8(SiO4)6O2∶ Pb2 , Tm3 phosphors, excitation into the Pb2 at 266 nm(1S0-3P1)yields the emissions of Gd3 at 311 nm(6P-8S)and Tm3 at 367 nm(1D2 -3H6)and 456 nm(1D2-3F4), indicating that energy transfer processes of Pb2 - Gd3 and Pb2 - Tm3 have occurred in the host lattices. 相似文献
3.
Spherical YAG:Ce3 phosphor particles with narrow size distribution were prepared by spray pyrolysis. The effects of the concentration of solution, the flow rate of carrier gas and the annealing temperature on the phosphor morphology were studied. The productivity of precursor particles shows a trend of drop after rising with the increase of concentration. Raising the flow rate of nitrogen can improve the productivity of the precursor particles. Phosphor prepared by spray pyrolysis has obviously higher emission intensity than that synthesized by solid state reaction, spray pyrolysis makes Ce3 ions well distributed in the crystal lattice as the luminescent centers, and phosphor particles have regular sphericity and narrow size distribution. 相似文献
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The (Ba1-xSrx)2SiO4∶Eu2 green-emitting phosphors were synthesized by conventional solid-state reaction in a CO-reductive atmosphere, and their luminescent properties were investigated. The XRD data show that the Ba/Sr ratio not only affects the lattice parameters, but also influences the emission peak. The excitation spectra indicate that this phosphor can be effectively excited by UV light from 370 to 470 nm. The emission band is due to the 4f65d1→4f7 transition of the Eu2 ion. With an increase in x, the emission band shifts to longer wavelength and the reason was discussed. The emission spectra exhibit a satisfactory green performance under different excitation wavelength(380, 398, 412, 420, 460 nm). (Ba1-xSrx)2SiO4∶Eu2 is a promising phosphor for green white-lighting-emission diode by ultraviolet chip. 相似文献
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Ca2RE8(SiO4)6O2:A (RE=Y, Gd; A=Pb2 , Mn2 ) phosphor films were dip-coated on quartz glass substrates through the sol-gel process. X-ray diffraction (XRD), photoluminescence (PL) spectra as well as lifetimes were used to characterize the resulting films. Under short wavelength UV excitation, the film showed a red emission with medium intensity. The decay curve of Mn2 luminescence in Ca2Gd8(SiO4)6O2:Pb Mn film could be fitted into a single exponential function. The lifetime of Mn2 was 10.21 ms in Ca2Gd8(SiO4)6O2. 相似文献
7.
Calcium magnesium chlorosilicate doped by europium, Ca8Mg(SiO4)4Cl2:Eu2 , was prepared by the solid state reaction at high temperature. The compound obtained is pure Ca8Mg(SiO4)4Cl2 phase with cubic structure. Its average particle size is 5 μm, and it has good dispersity and morphological form. The excitation spectrum of Ca8Mg(SiO4)4Cl2:Eu2 is a wide band, which covers from 270 to 480 nm. The emission spectrum is also a wide band peaked at 510 nm. The luminescent intensity reaches to the maximum when the concentration of Eu2 is 2%. The wavelength of emission and excitation of the phosphor with various Eu2 contents keeps constant. This spectrum range matches violet and blue LED chips very well, and its strong luminescence intensity is suitable for a green phosphor of tricolor phosphor of white light LED. 相似文献
8.
Sol-gel method was utilized to synthesize two different series of red silicate phosphors:MgSiO3 and Mg2SiO4 powder samples doped with Mn2 , conducted the investigation of red long-lasting phosphor: MgSiO3:Eu2 , Dy3 , Mn2 . TGA curves of the gel precursor for two series depicted that the loss of residual organic groups and NO3 groups occurs below 450 ℃. According to the XRD patterns, the major diffraction peaks of the MgSiO3 and Mg2SiO4 series are consistent with a proto-enstatite structure (JCPDS No.11-0273) and a forsterite structure (JCPDS No.85-1364) respectively. With the excitation at 415 nm, the red emission band of Mn2 ions is peaked at 661 nm for MgSiO3:1%(atom fraction) Mn2 or 644 nm for Mg2SiO4:1%(atom fraction) Mn2 . Compared with Mg2SiO4:Mn2 samples, MgSiO3:Mn2 samples exhibit higher luminescence intensity and higher quenching concentration. In addition, the two series co-doped with Eu2 , Dy3 , Mn2 were also prepared. Photo-luminescence and afterglow properties of the two co-doped series were analyzed, which show that MgSiO3:Eu2 , Dy3 , Mn2 is more suitable for a red long-lasting phosphor. 相似文献
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Y0.9-xGdxEu0. 1 BO3 phosphors were synthesized by spray drying (SD) method, and the results were compared with those by conventional solid state (SS) and citrate gel (CG) methods. The PL intensity of phosphors increases with the increase of x value in Y0.9-xGdxEu0.1BO3(prepared by SD) due to an energy migration process like Gd^3 - (Gd^3 )nEu^3 occurred in the material. Conlpared with the latter two methods, the phosphor particles prepared by spray drying method have a better morphology, such as homogeneous size (about 1 - 3μm) with spherical shape and smooth surface.Furthermore, the spray drying-derived phosphors have higher photoluminescence (PL) intensity than those by citrate gel method, but still a little lower than those by the solid state method. 相似文献
10.
Long afterglow SrAl2 O4: Eu2 , Dy3 phosphor was synthesized by microemulsion method. The synthesized phosphor was characterized by XRD. XRD pattern indicates that the phosphor has monoclinic SrAl2 O4 crystal structre.The microstructure of the phosphor was investigated by SEM and TEM. The excitation spectrum, emission spectrum and afterglow decay curve were measured, the wide range of excitation wavelength indicated that the luminescent material could be excited by the light from ultraviolet ray to visible light, and the emission maximum was found to peak mainly at λem of 525 nm. The sample excited by ultraviolet visible light could emit bright green light. 相似文献
11.
The green phosphor for white LED, Ca8Mg(SiO4)4Cl2∶Eu2+, Mn2+, was synthesized by high temperature solid state reaction under reducing atmosphere. During the process of the phosphor prepared, the excess CaCl2 can improve the intensity of emission. The experimental results indicate that there is an effective energy transfer from Eu2+ to Mn2+in Ca8Mg(SiO4)4Cl2 host. This kind of energy transfer may be due to resonance transfer, and this energy transfer is limited. 相似文献
12.
BaMgAl10O17: Eu2 phosphors was prepared by the solid-reaction method.Y2SiO5 was coated uniformly on the surface of phosphor by the surface-coated method, and the luminescent and deterioration properties were discussed.The XRD and SEM results show that Y2SiO5 film is produced on the surface of BAM phosphor.The emission spectrum analysis shows that the peak of the phosphor does not change after coating.The two phosphors were applied to lamps and the deterioration was tested at different ignited time.The keep ratio of luminous flux of the phosphor coated with Y2SiO5 is higher than that of the uncoated phosphor. 相似文献
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Nanoparticlesandnanoclustermaterialsareanewclassofadvancedmaterialsexhibit inguniquechemicalandphysicalpropertiescomparedtothoseoftheirbulkmaterials[1 ] .Y2 O3 :Euisanefficientred emissionphosphorwhichhasbeenusedinfluorescentlights (FL)andcathoderaytube (CRTs… 相似文献
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SrAl2O4 :Eu2+, Dy3+ Long Afterglow Phosphors Prepared by Chemical Coprecipitation Method 总被引:1,自引:0,他引:1
SrAl2 O4: Eu2 , Dy3 long afterglow phosphors were prepared by chemical coprecipitation method. Ammonium carbonate and ammonium hydrogen carbonate were used as the precipitants. The preparation of the SrAl2 O4: Eu2 ,Dy3 precursor was completed at room temperature by controlling the concentration of the metal-salt solution, pH value of the system, etc. The phosphors were prepared by sintering the precursor at 1000 ~ 1200 ℃ in a weak reducing atmosphere for 2 h. The XRD, SEM, excitation spectra, emission spectra and afterglow decay of the samples were tested and the optimal synthesis conditions of the SrAl2O4: Eu2 , Dy3 long afterglow phosphors prepared by precipitation method were determined. The phosphor which had good luminescent properties is prepared and its persistent time can reach more than 1600 min. In the coprecipitation process, a small amount of glucose operates to refe the luminescent powders. The particle size of the phosphor can be less than 1 μm. The sintering temperature of the sample prepared by the coprecipitation method is much lower than that of the one prepared by the high temperature solid state method.Compared with the high temperature solid state method, a clear blue shift occurs in the excitation and emission spectra of the samples. 相似文献
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Silicagelphosphorsdopedrareearthionshave attractedgreatattentionofmanyresearchersdueto theseadvantages,suchashighersamplehomogeneity,purityandstable,efficientandenvironmentallyfriend lyphotoluminescencematrixmaterials,whichisless toxicleadtonetconversione… 相似文献
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A series of phosphor of MO-RE2 O3-B2 O3: Eu, Mn ( M = Mg, Ca, Sr; RE = Y, La, Gd) were prepared and studied.Excitation spectra exhibited high absorption in UV region (370 ~ 400 nm).There existed two valence states for europium ions Eu2 and Eu 3 , the broad emission band peaking at 515 nm correspond to the 5d-4f emission transition of Eu2 , the sharp emission peaking at 590 and 610 nm correspond to the 5D0→7FJ(J = 1,2,3,4) emission transition of Eu 3 By the introduction of Mg and Y into MO-RE2O3-B2O3: Eu, blue-green emission was restrained ultimately and red emission peaking at 610 nm was enhanced strongly, intensity and colorimetric purity of red light were both enhanced.Furthermore, Mg1-xSrxO-Y2O3-B2O3: Eu was also researched, the introduction of Sr into MgO-Y2O3-B2O3:Eu gives rise to a shift to longer wavelengths of the position of the excitation peak, and the emission spectra varies with the increasing of x simultaneously. 相似文献
17.
Phosphor SrGa2S4Eu2 was synthesized with a high temperature solid state reaction.Its absorption spectrum, photoluminescence spectra, and fluorescence lifetime were studied in details.The excitation spectrum extended from UV to visible light region, and matched the emission of GaN chip.(Sr1-xEux)Ga2S4 emits strong green light and the concentration quenching did not occur; while the thermal quenching was evident.The emission peak shifted to long wavelength with increasing Eu2 concentration because of the changing of the crystal field strength.The lifetime of Eu2 ion was in the order of microsecond, which was reasonable for d→f transition.The electroluminescence spectrum of as-fabricated PC-LED at IF=20 mA was measured and most of the blue light of blue-LED chip at 460 nm was absorbed by the phosphor and simultaneously down-converted into an intensive green light at 540 nm.The color coordinate was (0.32, 0.63).SrGa2S4Eu2 was a promising phosphor for GaN-based green LEDs. 相似文献
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Eu(Ⅲ)-Pyromellitic acid[PMA]-1,10-phenanthroline (phen) ternary luminescent complex was prepared in ethanol and water mixed solvent. The elemental analysis, inductively coupled plasma-atomic emission spectroscopy (ICP-AES) fourier-transform infrared spectroscopy (FT-IR) indicates that its chemical constitution is Eu4(PMA)3(phen)0.75·7H2O. TG-DTA curves indicated that the complex is heat stable at the temperature of 430 ℃. The XRD patterns showed that the complex is a new crystal different from the two ligands' structures. SEM image indicates that the complex is in block shape and disperses well. Photoluminescence (PL) analysis indicates that the complex emits Eu3 characteristic luminescence under ultraviolet excitation. 相似文献
20.
Luminescent properties of Ca2SiO4:Eu3+ red phosphor for trichromatic white light emitting diodes 总被引:3,自引:0,他引:3
The luminescent properties of Eu3 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 Eu3 . 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 ef- fects of the Eu3 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 Eu3 ions was 0.3 mol–1, and Li ions gave the best improvement to enhance the emission intensity. Ca2SiO4:Eu3 , Li was thus suitable for low-cost trichromatic white light emitting diodes (WLED) based on UV InGaN chip. 相似文献