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1.
Lanthanide ions doped luminescent materials are widely studied for latent fingerprint detection. However, most of these materials are synthesized at very high temperatures and use UV C light for visualization, which is harmful to eye, skin, etc. Herein, the Gd0.95Eu0.05PO4 nanorods synthesized by a simple co-precipitation method at 185 °C were reported for latent fingerprint visualization under 395 nm light. The Gd0.95Eu0.05PO4 nanomaterial has monoclinic crystal structure and shows rod-shaped morphology. Further, these Gd0.95Eu0.05PO4 nanorods exhibit excellent photoluminescence properties and strong fuchsia emission under UV light. These nanorods have been employed for developing latent fingerprints on various porous and non-porous substrates by the powder dusting technique, which exhibits clear and well defined details with high contrast, selectivity and sensitivity under 395 nm UV light. Latent fingerprints developed after 72 h of their deposition also show clear contrast with these nanorods. Therefore, the Gd0.95Eu0.05PO4 nanorods can be used for latent fingerprint visualization applications.  相似文献   

2.
In the present communication,various fluxes blended Y_2 O_3:Eu~(3+)(5 mol%) nanopowders(NPs) were successfully fabricated by solution combustion method.PXRD pattern confirms body-centered cubic structure of the prepared samples.Energy band gap(Eg) of the fabricated products was estimated and is found to be in the range of 3.13-3.32 eV.Photoluminescence(PL) emission spectra exhibit sharp and intense peaks at ~579,592,614,657,704 nm corresponding to ~5 D_0→~7 F_J(J = 0,1,2,3 and 4) transitions of Eu~(3+) ions.Significance of fluxes for enhancing the PL emissions was extensively studied.Photometric studies of the prepared samples are located in pure red region.Optimized NPs were explored as a novel sensing agent for visualization of latent fingerprints(LFPs) on various surfaces including porous,semiporous and non-porous surfaces followed by powder dusting technique.Various experiments including aging,temperature,scratching and aquatic fresh water treatment tests were performed to evaluate applicability of the fabricated NPs.Visualized LFPs exhibit well defined ridge details including most authenticated sweat pores are also revealed with high sensitivity,selectivity,little background hindrance and less toxicity.Aforementioned results evidence that the method and fabricated NPs can be considered to be simple,rapid and economical and provide novel sensing platform for LFPs visualization in prospective forensic applications.  相似文献   

3.
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   

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.
Latent fingerprints (LFPs) were the most significant identification method for individualization. Most commonly available fingerprints (FPs) in crime spot investigation were latent and patent types. Generally,LFPs were invisible and thus the effective visualization technique necessitates for the analysis of such FPs. In the past years, many traditional visualization techniques have been employed, but suffered with low resolution, sensitivity, contrast and high background noise. To overcome such limitations, we synthesized Sm~(3+) doped CaSiO_3 nanophosphors (NPs) via an ultrasound irradiation route using mimosa pudica (m. p.)leaves extract as a bio-surfactant. The morphological behavior of the prepared samples was extensively studied by varying the concentration of the m. p. extract, ultrasound irradiation duration, pH level of the precursor solution and sonication power. The photoluminescence (PL) emission spectra exhibit characteristic peaks at~561,601 and 647 nm, which were attributed to~5G_(5/2)→~6H_J(J=5/2,7/2 and 9/2) transitions of Sm~(3+) ions.The Judd-Ofelt(J-O) intensity parameters and other radiative properties were estimated using PL data. The Commission International de I'Eclairage (CIE) color coordinates were positioned in orange-red region shows average correlated color temperature (CCT) value of~3576 K. The optimized samples can be used as a labeling agent for the visualization of LFPs on various porous and non-porous surfaces under normal light irradiation. The visualized FPs reveals well defined ridge characteristics, namely whorl, loop,arch, bifurcation, eye, island, bridge, sweat pores, etc, with high sensitivity, selectivity, low contrast and background hindrance. Aforementioned results evidence that the prepared CaSiO_3:Sm~(3+) NPs were promising luminescent materials for solid state lighting and forensic applications.  相似文献   

6.
The present paper summarises the synthesis of La3+ doped zinc oxide nanoparticles using Aloe vera gel by solution combustion method and the characterization using a powder X-ray diffractometer (PXRD), a transmission electron microscope (TEM), an X-ray photometric spectrometer (XPS), a Raman spectrometer and their applications in optical devices and latent fingerprinting. PXRD pattern confirms the crystallite size of La3+ doped ZnO varies from 13 to 20 nm. Crystallite size varies inversely with doping concentration. Photoluminescence properties are found to be the maximum for 2 mol% doping concentration. PL spectra extends the use of ZnO:La3+ nanoparticles in blue green LED. These nanoparticles also have superior property as a fluorescent labels in fingerprints.  相似文献   

7.
CaWO4:xEu3+,yTm3+crystals were obtained by facile synthesis at low temperature by the microwaveassisted hydrothermal method(MAH).The phase formation,morphology,luminescent properties and ene rgy transfer were investigated.The X-ray diffraction(XRD)re sults show the formation of a scheelitelike tetragonal structure without the presence of secondary phases.The growth mechanism of hierarchical micro structures based on self-assembly and Ostwald-ripening processes was evaluated,obtaining different types of morphologies.The luminescence spectra of CaWO4:Eu3+,Tm3+at 325 nm excitation show the predominance of red emission at the 5 D0→7 F2(Eu3+)transition at 624 nm.This feature signals dominant behavior of the electric dipole type.The presence of Tm3+is notably evident in the absorption spectra by the related excitation transitions:3 H6→1 G4,3 H6→3 F3 and 3 H6→3 H4.Color parameters are discussed to characterize CaWO4:Eu3+,Tm3+emission.The study of the emission spectrum as a function of the concentration of Eu3+(x mol%)and Tm3+(y mol%)indicates that the CaWO4:Eu3+,Tm3+phosphors show stronger red emission intensity and exhibit the CIE value of x=0.63 and y=0.35.The photoluminescence results show 97%high color purity for CaWO4:4 mol%Eu3+,a high CRI(92%)and a low CCT of 1085 K.These results demonstrate that the CaWO4:Eu3+,Tm3+red phosphors are promising as color converters for application in white light-emitting diodes and display devices.  相似文献   

8.
In this work, CaF_2:Ln~(3+)(Ln:Er,Er/Yb)/Nafion composite films were prepared using Nafion as modifications and matrices by dripping method. The composite films were characterized by Fourier transform infrared spectroscopy(FT-IR), X-ray diffraction(XRD) and scanning electron microscopy(SEM). Composite films are transparent and CaF_2:Ln~(3+)(Ln:Er,Er/Yb) nanoparticles are well dispersed in Nafion films.The thicknesses of CaF_2:Er~(3+)/Nafion and CaF_2:Er~(3+),Yb~(3+)/Nafion composite film are about 77 and 73 μm,respectively. The nanoparticles in composite film possess cubic phase. CaF_2:Er~(3+),Yb~(3+)/Nafion composite film has stronger characteristic emission of Er~(3+) around 1530 nm with full width at half-maximum(FWHM) of 73 nm and longer luminescence lifetimes of 22.04 μs(25.03%) and 100.77 μs(74.97%).  相似文献   

9.
In this work, Eu3+-doped CsPbCl2Br1 in borosilicate glass was successfully synthesized by the melt quenching annealing technique and crystallization method. This work reports a novel Eu3+-doped CsPbCl2Br1 perovskite quantum dots (QDs) glass with high sensitivity for optical temperature sensing. The relation of fluorescence intensity ratio (FIR) with the temperature was studied in the temperature range of 80–440 K. Notably, the maximum absolute temperature sensitivity (Sa) and relative temperature sensitivity (Sr) of Eu3+-doped CsPbCl2Br1 perovskite QDs glass can reach as high as 0.0315 K–1 and 3.097%/K, respectively. Meanwhile, Eu3+-doped CsPbCl2Br1 QDs glass demonstrates good water resistance, excellent thermal and cold cycling stability performance. The Eu3+-doped QDs glass materials can bring inspiration to the future exploration of rare earth ion-doped QDs glass material on the application of optical temperature sensing in the future.  相似文献   

10.
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   

11.
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   

12.
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   

13.
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.  相似文献   

14.
The degradation of materials plays an important role in their application and service process. In this work, the moisture-induced degradation of SrLiAl3N4:Eu2+ (SLAN), a very promising narrow-band red-emitting phosphor, was comprehensively investigated by treating it in two different moisture conditions in order to reveal the potential mechanism and optimize the luminescence properties. The degradation rate gradually slows down with the decreasing environmental humidity indicating that water plays a key role in the degradation. Moreover, we take the other option with 100% humidity at different temperatures for rapid degradation. In the rapid degradation, the luminescence of SLAN is quenched quickly and the phase and microstructure change obviously, with the phosphor being bleached. The host turns into NH3, Al2O3, Sr3Al2(OH)12 and LiAl2(OH)7 finally. It is further confirmed that the rapid degradation occurs with the help of water and the phosphor is oxidized during this process.  相似文献   

15.
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   

16.
Study of the local environment of certain ion is quite a complex problem. Due to the unique luminescent properties, Eu3+ ions can be used as a structural probe. In this paper, effect of doping concentration, excitation wavelength and excitation mechanism on asymmetry ratio was systematically studied using Y3Al5O12:Eu3+, YVO4:Eu3+ and Y2O3:Eu3+nanophosphors. The asymmetry ratio gives information about the local surrounding and environmental changes around the Eu3+ ions. Asymmetry ratios of YAG:Eu3+ and YVO4:Eu3+ nanopowders were calculated using standard technique and the obtained average values were found to be 0.75 and 8.2, respectively. However, it is found that standard method of asymmetry ratio calculation is suitable only for samples where all Eu3+ ions occupy one site. The “multisite model” of asymmetry ratio calculation was developed and used for Y2O3:Eu3+ nanocrystalline powders. Average value of asymmetry ratio for Eu3+ ions occupied “normal” sites is 6.0 and for Eu3+ ions occupied “defect” sites is 2.3.  相似文献   

17.
This study presents the photoluminescence characteristic analysis of a series of red phosphors of KAlSiO4:1.5 mol%Sm3+,x mol%Eu3+ (x = 2, 3, 4, 5, 6, 7) prepared via high-temperature solid-phase reaction. The results show that the X-ray diffraction (XRD) refinement results are reliable. The unit cell parameters and volume gradually decrease as the Eu3+ concentration increases, resulting in a grain size reduction of 10.22%. When x = 6, the emission peaks of Sm3+ at 564, 601, and 651 nm disappear completely, and the corresponding full width at half maximum becomes 0. At 610 nm, the emission peak intensity of Eu3+ is increased by a factor of 4.8. The resonant non-radiative energy transfer effect is greater than the co-excitation effect. A maximum energy transfer efficiency of 97.8% is achieved. The integral area at 610 nm is as high as 85%. The color purity of the phosphor is as high as 92.97%, and the internal quantum yield gradually changes from 32% to 51%. Ultimately, these results confirm that the silicate phosphor is suitable for the red component in the three primary color phosphors of white light-emitting diodes.  相似文献   

18.
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   

19.
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   

20.
A series of Tb~(3+) and Eu~(3+) co-doped NaY(WO_4)_2 phosphors were synthesized by hydrothermal reactions.The crystal structure,morphology,upconversion luminescent properties,the energy transfer from Tb~(3+) to Eu~(3+)ions and the ~5 D_4→ ~7 F_5 transition of the Tb~(3+) ion in NaY(WO_4)_2:Tb~(3+),Eu~(3+) phosphors were investigated in details.The results indicate that all the synthesized samples are of pure tetragonal phase NaY(WO_4)2.Furthermore,the micrometer-sized needle spheres and excellent dispersion of the particles are obtained by adding polyethylene glycol(PEG-2000) as the surfactant.Phosphors of NaY(WO_4)_2:Tb~(3+),Eu~(3+) exhibit the492 nm blue emission peak,546 nm green emission peak,595 nm orange emission peak and 616 nm red emission peak under 790 nm excitation.The energy transfer from Tb~(3+) to Eu~(3+) is a resonant transfer,in which electric dipole-dipole interaction plays a leading role.By adjusting the doping concentration of Eu~(3+) in NaY(WO_4)_2: 1.0 mol%Tb~(3+),xmol%Eu~(3+) phosphors,the emitting color of UC phosphors can be tuned from green to red.  相似文献   

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