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1.
In the present work, TiO2:Eu3+ (1 mol%–11 mol%) nano powders (NPs) were prepared via a facile one-pot hydrothermal method by using Epigallocatechin Gallate (EGCG) as bio-surfactant. The optimized TiO2:Eu3+ (5 mol%) NPs can be used as fluorescent labeling agent for visualizing of latent fingerprints (LFPs) on various porous and non-porous surfaces. The obtained results exhibit well defined ridge details with high sensitivity, selectivity, and low background hindrance which show greater advantages as compared to conventional powders. We demonstrated the viability of high-performance security labels thorough excellent luminescence for practical anti-mimetic applications. Morphology of the prepared samples is highly dependent on pH, concentration of the bio-surfactant, temperature and time durations. Photoluminescence (PL) emission spectra exhibit intense red emission at ~ 615 nm due to electric dipole transition (5D07F2). Photometric (CIE and CCT) results clearly show the intense warm red emission of the optimized samples. Therefore, this work offers a superior and universal luminescent label, which can be applied to visualize miniature LFPs particulars for individualization and consequently display great prospective in forensic investigation.  相似文献   

2.
High-sensitivity detection of porphyrin in blood is very important for the early diagnosis and treatment of porphyria.Based on the advantages of longer luminescence lifetime and lower background interference,organic afterglow molecular porphyrin detection probes were developed,but these probes show poor water solubility and insufficient luminescence intensity.Herein,we present an afterglow nanoprobe(Eu-NP) for porphyria detection in whole blood.The luminescent substance(europium complex) and the...  相似文献   

3.
A novel orange-red emitting Ba3Y4O9:Sm3+ phosphors were prepared by a high temperature solid-state reaction in air. X-ray diffraction (XRD), photoluminescence spectra, fluorescence decay and temperature-dependent emission spectra were utilized to characterize the structure and luminescence properties. The results show that the excitation spectrum includes a series of linear peaks at 350, 367, 382, 410, 424, 445, 470 and 495 nm, respectively. Under 410 nm excitation, the emission peaks were located at 574 nm (4G5/26H5/2), 608 nm (4G5/26H7/2), 659 nm (4G5/26H9/2) and 722 nm (4G5/26H11/2), respectively. The concentration quenching occurs when x equals 0.08 for Ba3Y4–xO9:xSm3+ phosphor and its mechanism is ascribed to the dipole–dipole interaction. The chromaticity coordinates of Ba3Y3.92O9:0.08Sm3+ phosphor are in the orange-red region. The temperature-dependent study shows that this phosphor has excellent luminescence thermal-stability. And the luminescence intensity of Ba3Y3.92O9:0.08Sm3+ phosphor at 473 K only declines by about 25.75% of its initial intensity. The experimental data indicate that Ba3Y4O9:Sm3+ phosphor may be promising as an orange-red emitting phosphor for white light emitting diodes.  相似文献   

4.
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.  相似文献   

5.
This work presents the synthesis of Y2O3:Eu3+,xCa2+ (x = 0 mol%, 1 mol%, 3 mol%, 5 mol%, 7 mol%, 9 mol%, 11 mol%) nanophosphors with enhanced photoluminescence properties through a facile solution combustion method for optoelectronic, display, and lighting applications. The X-ray diffraction (XRD) patterns of the proposed nanophosphor reveal its structural properties and crystalline nature. The transmission electron microscope (TEM) results confirm the change in the shape of the particle and aggregation of particles after co-doping with Ca2+. Fourier transform infrared spectroscopy (FTIR) and Raman vibrations also confirm the presence of Y–O vibration and subsequently explain the crystalline nature, structural properties, and purity of the samples. All the synthesized nanophosphors samples emit intense red emission at 613 nm (5D07F2) under excitation with 235, 394 and 466 nm wavelengths of Eu3+ ions. The photoluminescence (PL) emission spectra excited with 235 nm illustrate the highest emission peak with two other emission peaks excited with 466 and 394 nm that is 1.4 times higher than 466 nm and 1.9 times enhanced by 394 nm wavelength, respectively. The emission intensity of Y2O3:Eu3+,xCa2+ (5 mol%) is increased 8-fold as compared to Eu:Y2O3. Doping with Ca2+ ions enhances the emission intensity of Eu:Y2O3 nanophosphors due to an increase in energy transfer in Ca2+→Eu3+ through asymmetry in the crystal field and by introduction of radiative defect centers through oxygen vacancies in the yttria matrix. It is also observed that the optical band gap and the lifetime of the 5D0 level of Eu3+ ions in Y2O3:Eu3+,xCa2+ nanophosphor sample gets changed with a doping concentration of Ca2+ ions. Nanophosphor also reveals high thermal stability and quantum yield as estimating activation energy of 0.25 eV and 81%, respectively. CIE, CCT, and color purity values (>98%) show an improved red-emitting nanophosphor in the warm region of light, which makes this material superior with a specific potential application for UV-based white LEDs with security ink, display devices, and various other optoelectronics devices.  相似文献   

6.
A single-phase full-color emitting phosphor Sr2Ca2La(PO4)3O:Eu2+,Tb3+,Mn2+ was synthesized by the high temperature solid-state method. The phase formation, luminescence properties, thermal stability, and energy transfer from Eu2+ to Tb3+ and Eu2+ to Mn2+ in Sr2Ca2La(PO4)3O were investigated in details. Tunable emission color from blue to blueish green or orange can be observed under 365 nm near-ultraviolet excitation based on the energy transfer from Eu2+ to Tb3+ or Mn2+ ions by varying the ratio of Eu2+/Tb3+ or Eu2+/Mn2+ ions. White light was obtained with chromaticity coordinates of (0.3558, 0.3500) in the Sr2Ca2La(PO4)3O:0.04Eu2+,0.08Tb3+,0.40Mn2+ phosphor, suggesting their potential applications in white light emitting diodes.  相似文献   

7.
In this paper,effect of two strategies on afterglow behavior of Lu2O3:Eu single crystal scintillato r,Pr3+ codoping and solid solution with Sc2O3,were studied systematically.Two groups of Lu2O3:5 at%Eu,x at%Pr(x=0,0.2,0.5,1,2 and 5) and(Lu1-yScy)2O3:5 at%Eu(y=0,20 at%,50 at% and 70 at%) single crystals were grown by floating zone(FZ) method in air atmosphere.The structures of ...  相似文献   

8.
Nanosized 1 at% Sm3+doped Y2O3 powders were prepared by an ultrasound assisted sol-gel method.Y2O3:Sm3+powders crystallize in Y2 O3 pure cubic phase and XRD analysis shows that the as-used agitation protocol affects strongly the crystallite’s shape and mean size.The recorded emission spectra under λem=600 nm exhibit two absorption bands;the first one is assigned to O2-→Sm3+cha...  相似文献   

9.
Eu2+ activated BaSi2O2N2 oxynitride bluish-green phosphor was synthesized adopting conventional high-temperature solid-state reaction method, in which BaF2, Na2CO3 and NH4Cl were used as the fluxes. The phase formation, size distribution and microscopic morphology were characterized to investigate the influence of adding fluxes on photoluminescence properties. The results indicate that with the addition of BaF2 flux, the particle morphology becomes regular and size distribution narrows and the phase purity of BaSi2O2N2:Eu2+ phosphor can be improved effectively. The photoluminescence intensity of BaSi2O2N2:Eu2+ phosphor with BaF2 as flux gets enhanced obviously, which is much higher than that of Na2CO3, NH4Cl and without flux. The optimum content of BaF2 flux is 4 wt%, and the maximum photoluminescence intensity of the BaSi2O2N2:Eu2+ phosphor prepared with BaF2 flux rises to 141%, meanwhile, the phosphors with BaF2 flux exhibits low thermal quenching. The results indicate that the BaSi2O2N2:Eu2+ is sort of promising bluish-green phosphor for application in full-spectra LED.  相似文献   

10.
In this work, the Gd3+/Eu3+ activated Ba3Y4O9 (BYO) phosphors were successfully synthesized via coprecipitation method at 1400 °C. The precursor composition, crystal structure stability, microscopic morphology, photoluminescence (PL)/photoluminescence excitation (PLE) spectra and fluorescence attenuation analysis of the phosphors are discussed in detail. The chemical composition of the precursor was determined by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetry (TG) analysis; According to field emission-scanning electron microscopy (FE-SEM) analysis, it is found that the particle size of phosphor is uniform and the agglomeration is few. According to PL/PLE spectra analysis, Ba3Y3.28Eu0.6Gd0.12O9 phosphors has the strongest excitation band at 260 nm and the strongest emission band at 614 nm, and the fluorescence intensity of Ba3Y3.28Eu0.6Gd0.12O9 is higher than that of Ba3Y3.4Eu0.6O9. The quenching concentration of Eu3+ in Ba3Y3.88–4xEu4xGd0.12O9 phosphors is x = 0.15 and the mechanism of quenching concentration of Eu3+ is electric dipole-quadrupole type interactions. The lifetime value of Ba3Y3.88–4xEu4xGd0.12O9 (x = 0.15) phosphors is 0.686 ms and decreases with the increase of Eu3+ content. In addition, the CIE chromaticity diagram of Ba3Y3.28Eu0.6Gd0.12O9 phosphors is (0.66, 0.34). Finally, the lamp beads assembled with Ba3Y3.28Eu0.6Gd0.12O9 phosphors have an ideal luminous effect. Therefore, the Ba3Y3.88–4xEu4xGd0.12O9 phosphors designed in this work may hopefully meet the requirements of various lighting and optical display applications.  相似文献   

11.
Europium(Eu~(3+)) doped glasses of chemical compositions(55-x)B_2O_3:10 SiO_2:25 Y_2O_3:10CaO:xEu_2O_3,where x denotes mol% and ranges 0≤ x ≤ 2.5, were synthesized by adopting conventional melt quenching technique, Physical properties like density, molar volume, polaron radius, inter-ionic distance and field strength of the glass samples were investigated to assess the impact of Eu_2O_3. Optical and luminescence properties of the glasses were characterized with optical absorption, photoluminescence,X-ray induced emission spectra, temperature dependence emission spectra and decay times. Judd-Ofelt(JO) intensity parameters(Ω_λ) of the glasses were evaluated based on the absorption spectrum of 0.5 mol%. JO parameters, calculated from absorption spectra with thermal corrections on oscillator strength, were used to evaluate radiative properties such as radiative transition probability(A_R),branching ratio(β_R), stimulated cross section emission(σ) and radiative lifetime(τ_R) for ~5D_0→~7 F_J(J = 0,1,2,3 and 4) transitions. The decay rate of ~5D_0 fluorescent level for all the glass samples was single exponential. Lifetimes of the ~5D_0 level were decreased with increasing concentrations of Eu~(3+)ions from 0.05 mol% to 2.5 mol% which might be due to energy transfer through cross-relaxation in the glasses. The chromaticity coordinates(x, y) were similar for all BSYCaEu glasses and were located at the red region of CIE 1931 color chromaticity diagram. Hence, these results confirm that the Eu~(3+) doped BSYCaEu glasses could be useful for visible red lasers and glass scintillation applications.  相似文献   

12.
Long-lasting phosphor Y2O2S∶Eu3 , Mg2 , Ti4 was synthesized by a flux method and their luminescence properties were investigated. The result indicates that the unit cell parameter c is linearly increased with the increase of Eu2O3 content in Y2O2S∶Eu3 x(0.01≤x≤0.10). On the other hand, the change of unit cell parameter a is not linear dependence. In the Y2O2S∶ Eu3 crystal structure, Eu3 ions only replaced Y3 ions′ places in which it posited center position of c axis. With the increase of Eu2O3 content, the position of the strongest emission peak changed from 540 nm (5D1→7F2 transition) to 626 nm (5D0→7F2 transition), and the maximum intensity was obtained when x=0.09 in Y2O2S∶Eu3 x(0.01≤x≤0.10). This is due to the environment of trivalent europium in the crystal structure of Y2O2S. Doping with Mg2 or Ti4 ions alone cannot get the good long-lasting afterglow effect, whereas co-doping with Mg2 and Ti4 ions and excited with 365 nm ultraviolet light, a strong thermoluminesence peak appeared, red and orange long-lasting phosphorescence (LLP) was also observed and the phosphorescence lasted nearly 3 h in the light perception of the dark-adapted human eye (0.32 mcd*m-2). Thus the LLP mechanism was analyzed.  相似文献   

13.
As a cyan-emitting oxonitridosilicate phosphor,BaSi2O2N2:Eu2+can be used as a competent cyan compensator to improve the color rendering index of white light-emitting diodes(WLEDs).However,low luminescence efficiency and poor thermal stability of this type of phosphor seriously suppress its actual application in full-spectrum lighting.The replacements of Ba2+by Lu3+and Ba2+-Si4+by Lu3+-Al3+can greatly increase the luminescence intensity and improve the thermal stability at the same time.With Lu3+doping,the internal quantum efficiencyηIQE Ba0.925Si2O2N2:0.03 Eu2+,0.045 Lu3+is 24.08%higher than that of Ba0.97Si2O2N2:0.03 Eu2+.After Al3+co-doping,theηIQE is further increased by 10.31%compared to Ba0.925Si2O2N2:0.03 Eu2+,0.045 Lu3+.When the temperature rises to 473 K,the luminescence intensity of Ba0.925Si2O2N2:0.03 Eu2+,0.045 Lu3+maintains 62.32%of that at room temperature,which increases by 17.35%in relative to the Ba0.97Si2O2N2:0.03 Eu2+,while the luminescence intensity of Ba0.925Si1.97O2N2:0.03 Eu2+,0.045 Lu3+,0.03 Al3+keeps 73.87%of the initial value,which increases by18.52%compared to Ba0.925Si2O2N2:0.03 Eu2+,0.045 Lu3+.The mechanisms for luminescence and thermal stability improvement are proposed.The Ba0.925Si1.97O2N2:0.03 Eu2+,0.045 Lu3+,0.03 Al3+cyan phosphor,Y3 Al5 O12:Ce3+yellow phosphor and CaAlSiN3:Eu2+red phosphor are mixed thoroughly and coated on a blue LED(450 nm)to assemble a WLED.The WLED demonstrates a color rendering index(Ra)of 97.1 at150 mA,and the R1-R15 values are all above 90.The results indicate that as an effective cyan compensator in WLED,the BaSi2O2N2:Eu2+,Lu3+,Al3+phosphor has great application prospect in the field of full-spectrum lighting.  相似文献   

14.
15.
Red emitting phosphors play a significant role in accelerating the improvement of illumination quality for white light emitting diodes (WLEDs). In this work, by using solid-state reaction method, an efficient novel Ba2LuNbO6:Eu3+ phosphor with double-perovskite structure was successfully prepared. Here, a series of Ba2LuNbO6:Eu3+ red phosphors can be efficiently pumped by the near-ultraviolet (UV) light and then present high-brightness at orange emission (598 nm, 5D07F1) and red emission (610 nm, 5D07F2). The ratio values of 610 to 598 nm in Ba2LuNbO6:Eu3+ phosphors exceed 1 when the content of Eu3+ is larger than 0.4 mol, because the occupation of Eu3+ ions is changed from Lu3+ ions with symmetric sites to Ba2+ ions with asymmetric sites. Besides, the optimized concentration of Eu3+ at the 5D07F2 transitions is obtained when x = 1, indicating that there is non-concentration quenching in Ba2LuNbO6:Eu3+ phosphors. Moreover, the CIE chromaticity coordinates of Ba2LuNbO6:Eu3+ was calculated to be (0.587, 0.361), the color purity was calculated to be 72.26% and internal quenching efficiency (IQE) was measured to be 67%. Finally, the thermal stability of Ba2LuNbO6:Eu3+ phosphors was also studied. Our work demonstrates that the novel double-perovskite red-emitting Ba2LuNbO6:Eu3+ phosphors are prospective red emitting elements for WLEDs applications.  相似文献   

16.
45P2O5–15BaO–25ZnO–15B2O3 glasses doped with different concentrations (0 mol%, 0.1 mol%, 0.25 mol%, 0.5 mol%, and 0.75 mol%) of Gd3+ were prepared by a melt-quenching method and treated to fabricate glass-ceramics containing BaZn2(PO4)2 crystals by controllable crystallization. The structural, optical, and dosimetric properties were investigated. FTIR spectra indicate that the glasses are composed of [PO4], [BO3], and [BO4] basic structural units. The XRD pattern analysis indicates that the samples contain BaZn2(PO4)2 crystals. In the photoluminescence (PL) spectra, two emission bands are observed at 307 and 313 nm due to the 6P5/28S7/2 and 6P7/28S7/2 transitions of Gd3+, respectively. The OSL dosimetric properties of glass-ceramics were studied further under beta radiation of 90Sr. The optimal Gd3+ doping concentration of 0.5 mol% was determined. The fading of the OSL signal shows that the CW-OSL signal of Gd3+-doped BaZn2(PO4)2 glass-ceramics decays by about 58.95% within 120 h, and the intensity remains stable thereafter. The thermoluminescence (TL) curve has three peaks at 164, 240, and 344 °C. Minimum detectable dose (MDD) of the 0.5 mol% Gd3+-doped BaZn2(PO4)2 glass-ceramics was calculated as 0.675 mGy. The samples also exhibit good signal reusability and a broad linear dose-response range (0.3–500 Gy). Results show the excellent dosimetric properties of Gd3+-doped BaZn2(PO4)2 glass-ceramics and their potential application in radiation dosimetry.  相似文献   

17.
Compared with Y3Al5O12:Ce3+,Y3MgAl3SiO12:Ce3+(YMASG:Ce3+) reveals great potential for highpower white lighting with red-shift spectrum.Herein,YMASG:Ce3+ transparent ceramics were explored to be synthesized in the air following hot isostatic pressure(HIP) treatment to obtain tunable and optimized optical properties.Then phase purity,microstructure,transmittance,and photoluminescence of YM...  相似文献   

18.
The Y2O3 : EU^3 + hollow spheres were synthesized using the template-mediated method. XRD patterns indicated that the broadened diffraction peaks resulted from nanocrystals in Y2O3 : EU^3 + shells of hollow spheres. XPS spectra showed that the Y2O3 : EU^3 + shells were linked with silica cores by a Si-O-Y chemical bond. SEM and TEM observations showed that the size of the SiO2/Y2O3 : EU^3 + core-shell particle was about 100 nm, and the thickness of the Y2O3 : EU^3 + hollow sphere was less than 5 nm. The photoluminescence spectra of the SIO2/Y2O3 : EU^3 + core-shell materials and Y2O3 : EU^3 + hollow spheres had red luminescent properties, and the broadened emission peaks came from nanocrystals composed of the Y2O3 : EU^3 + shell.  相似文献   

19.
The phase and morphology transformation during the hydrothermal treating process of Y2O3 was evaluated with X-ray diffcrcnce (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), particle size and specific surface area determination.The results showed that the cubic Y2O3 did not transfer into hexagonal Y(OH)3 in pure water. Therefore, pure hexagonal Y(OH)3 with nanotube and microrod morphologies were obtained by hydrothermal treating Y2O3 at 150℃ for 12 h in 15 ml of 2 mol/L NaOH solution with and with-out PVA or PEG It was suggested that the characteristic preferential growth of Y(OH)3 was attributed to the structure anisotropy of hexahedron Y(OH)3. The addition of PVA or PEG could promote the forming process of nanotubes by selective adsorption on different crystal planes,which altered the growth rate along different directions and resulted in the diffusion limit of constructing ions in the center top of rods. Finally,Y(OH)3:Eu and Y2O3:Eu nanotubes were also synthesized by using this method, and their photoluminescence properties were evaluated.  相似文献   

20.
Alkali metal ions(M~+ = Na~+,Li~+,K~+) co-doped ZnAl_2O_4:Eu~(3+)(5 mol%)(ZAE) nanopowders(NPs) were prepared via solution combustion route using Mimosa pudica(MP) leaves extract as a fuel. PXRD results of co-doped samples enhance the crystallinity and grain growth. Photoluminescence(PL) of the prepared ZAE and ZAE:M~+(M~+ = Na~+, Li~+, K~+) NPs shows intense emission peaks in the range of 550-750 nm and ascribed to ~5D_0→~7F_J(J=0-4) transitions of Eu~(3+) ions, respectively. A 2-fold enhancement in PL intensity was observed in Li~+ co-doped samples. The optimized ZnAl_2O_4:Eu~(3+)(5 mol%), Li~+(1 wt%)(ZAEL)NPs were used to visualize LFPs on various porous, semi-porous and non-porous surfaces through robust powder dusting technique. The visualized latent fingerprints(LFPs) reveal well defined level 1-3 ridge characteristics under several tests such as fingerprint aging and fresh water treatment for various time durations. The obtained results clearly evidence that the prepared NPs are quite useful for multifunctional applications such as advanced forensic and solid state lightning.  相似文献   

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