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1.
YVO4:Yb3+,Er3+; YVO4:Yb3+,Tm3+; and YVO4:Yb3+,Er3+,Tm3+ were all synthesized via sol-gel method with a subsequent thermal treatment. Specifically, YVO4:Yb3+,Er3+,Tm3+ phosphors were prepared with different annealing temperatures to study the influence of temperature. The transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffractometer (XRD), and photoluminescent (PL) spectrofluorometer were used to investigate the morphology, crystal structure, and up-conversion luminescent properties of all samples. In summary, all samples were granular-like nanoparticles and well crystallized with the same tetragonal phase as YVO4. Under the irradiation at 980 nm, YVO4:Yb3+,Er3+ phosphors can generate green emission at 525 and 553 nm and red emission at 657 nm, while YVO4:Yb3+,Tm3+ phosphors can generate blue emission at 476 nm, red emission at 648 nm, and near-infrared emission at 800 nm. Notably, YVO4:Yb3+,Er3+,Tm3+ samples can exhibit green emission, blue emission, red emission, and near-infrared emission at the same time, which might endow the as-prepared samples with potential applications in many fields, such as luminous paint, infrared detection, and biological label. 相似文献
2.
Biocompatible upconversion nanoparticles with multifunctional properties can serve as potential nanoprobes for multimodal imaging. Herein, we report an upconversion nanocrystal based on lanthanum fluoride which is developed to address the imaging modalities, upconversion luminescence imaging and magnetic resonance imaging (MRI). Lanthanide ions (Yb3+ and Ho3+) doped LaF3 nanocrystals (LaF3 Yb3+/Ho3+) are fabricated through a rapid microwave-assisted synthesis. The hexagonal phase LaF3 nanocrystals exhibit nearly spherical morphology with average diameter of 9.8 nm. The inductively coupled plasma mass spectrometry (ICP-MS) analysis estimated the doping concentration of Yb3+ and Ho3+ as 3.99 and 0.41%, respectively. The nanocrystals show upconversion luminescence when irradiated with near-infrared (NIR) photons of wavelength 980 nm. The emission spectrum consists of bands centred at 542, 645 and 658 nm. The stronger green emission at 542 nm and the weak red emissions at 645 and 658 nm are assigned to 5S2 → 5I8 and 5F5 → 5I8 transitions of Ho3+, respectively. The pump power dependence of luminescence intensity confirmed the two-photon upconversion process. The nanocrystals exhibit paramagnetism due to the presence of lanthanide ion dopant Ho3+ and the magnetization is 19.81 emu/g at room temperature. The nanocrystals exhibit a longitudinal relaxivity (r 1) of 0.12 s?1 mM?1 and transverse relaxivity (r 2) of 28.18 s?1 mM?1, which makes the system suitable for developing T2 MRI contrast agents based on holmium. The LaF3 Yb3+/Ho3+ nanocrystals are surface modified by PEGylation to improve biocompatibility and enhance further functionalisation. The PEGylated nanocrystals are found to be non-toxic up to 50 μg/mL for 48 h of incubation, which is confirmed by the MTT assay as well as morphological studies in HeLa cells. The upconversion luminescence and magnetism together with biocompatibility enables the adaptability of the present system as a nanoprobe for potential bimodal imaging. 相似文献
3.
The Ca12Al14O33: Yb3+/Yb2+ single phase nano-phosphor has been synthesized through combustion route and its luminescence and lifetime studies have been
carried out up to 20 K using 976 and 266 nm excitations. The samples heated in open atmosphere have shown the presence of
Yb in Yb3+ and Yb2+ states. The 976 nm excitation results a cooperative upconversion emission at 486 nm due to the Yb3+ state and a broad band in the blue region and has been assigned to arise from the defect centers. The 266 nm excitation on
the other hand results a broad emission band even from as-synthesized phosphor without doping of Yb, the width of which increases
in presence of Yb due to the emission from Yb2+ ions formed in heated samples. The white emission covers almost whole visible region with bandwidth 190 nm. The ions in Yb2+ state has been found to increase with the increase in heating temperature up to 1,273 K. A back conversion of Yb2+ to Yb3+ has been observed for higher temperatures. Effect of boric and phosphoric acids as flux on the emission properties of Yb3+ and Yb2+ states have been examined and discussed. Quantum yield of emission has also been determined for different samples. 相似文献
4.
Yb3+-Tm3+ co-doped up-conversion powder phosphors using Zn(AlxGa1-x)2O4 (ZAGO) as the host materials were synthesized via solid-state reaction successfully. In addition, the morphology, structural characterization and up-conversion luminescent properties were all investigated by scanning electron microscope (SEM), x-ray diffraction (XRD) and fluorescence spectrophotometer (F-7000), respectively. Under the excitation of a 980 nm laser, all as-prepared powders can carry out blue emission at about 477 nm (corresponding to 1G4 → 3H6 transition of Tm3+ ions), and red emission at about 691 nm (attributed to 3F3 → 3H6 transition of Tm3+ ions). Also, the influence of doping Al3+ ions were investigated. In brief, the doping of Al3+ ions has no effect on the position of emission peak. Howbeit the up-conversion efficiency and intensity of ZAGO:Yb,Tm phosphors are stronger than ZGO:Yb,Tm and ZAO:Yb,Tm phosphors, while the crystallinity is the opposite. More particularly, all as-prepared powder phosphors emit strong luminescence, which is observable by the naked eye, demonstrating the potential applications in luminous paint, luminescent dye, etc. 相似文献
5.
We report spectroscopic and laser properties for propagation directions outside the principal axes of Yb3+-doped low symmetry laser crystals with a special devotion to the wavelength dependence anisotropy. We illustrate our report
with experimental data in the 900–1075 nm range of wavelengths from the Yb3+:La2CaB10O19 monoclinic crystal excited under laser diode pumping at 975 nm. This study, which makes easier the realization of Yb3+ lasers with an efficient free-running operation at the wavelength having the highest emission intensity or at a specified
wavelength, or emitting two frequencies with a specified frequency difference, is of promising interest for applications. 相似文献
6.
The mechanism of the upconversion processes in Y6O5F8: 2%Er3+/X%Yb3+ (X = 3, 10, 20) microtubes has been explored. The luminescent properties of the as prepared sample is investigated by utilizing up- /downconversion, decay and time resolve spectra. The results indicate that the red and green emission are clearly competitive depending on the Yb3+ concentration. High Yb3+ concentration induces the enhancement of the energy-back-transfer (EBT), process, which leads to the quenching of green emission and enhances the red emission. So it is possible to utilize the temporal evolutions of emission bands to deeply understand the color change UC mechanisms. 相似文献
7.
KY3F10:Ho3+ thin films were deposited by a pulsed laser deposition technique with Nd–YAG laser radiation (λ = 266 nm) on (100) silicon substrate. The XRD and FE-SEM results show improved crystalline structure for the film deposited at a pressure of 1 Torr. The AFM results show that the RMS roughness of the films increases with rise in argon gas pressure. The EDS elemental mapping shows Y-excess for all the films deposited under all pressures, and this is attributed to its higher mass and low volatility as compared to K and F. XPS analysis further confirmed Y-excess in the deposited films. Green PL emission at 540 nm was investigated at three main excitation wavelengths, namely 362, 416 and 454 nm. The PL emission peaks increase with rise in background argon gas pressure for all excitation wavelengths. The highest PL intensity occurred at excitation of 454 nm for all the thin films. In addition, faint red (near infrared) emission was observed at 750 nm for all the excitations. The green emission at 540 nm is ascribed to the 5F4–5I8 and 5S2–5I8 transitions, and the faint red emission at 750 nm is due to the 5F4–5I7 and 5S2–5I7 transitions of Ho3+. 相似文献
8.
Xiaofei Qu Yuchen Hou Junying Yang Meihua Liu Liang Shi Fanglin Du 《Journal of nanoparticle research》2017,19(5):172
In this paper, TiO2 particles (~30 nm) modified with Gd2O3-coating layer (~2 nm) for dye-sensitized solar cells (DSSCs) were fabricated via the hydrothermal method. Among the solar cells based on the Gd3+-doped TiO2 photoanodes, the optimal conversion efficiency was obtained from the 0.025Gd3+-modified TiO2-based cell, with a 17.7% improvement in the efficiency as compared to the unmodified one (7.18%). This enhancement was probably due to the improved UV radiation harvesting via a down-conversion luminescence process by Gd3+ ions, enhancement of visible light absorption and improved dye loading capacity. In addition, after Gd modification, a thin coating could be formed on the TiO2 nanoparticles, which worked as an energy barrier and resulted in a lower charge recombination. 相似文献
9.
Photoluminescence studies of pure and Dy3+, Eu3+ doped Sr2CeO4 compounds are presented by oxalate precipitation method for solid state lighting. The prepared samples also characterized by XRD, SEM (EDS) and FTIR spectroscopy. The pure Sr2CeO4 compound displays a broad band in its emission spectrum when excited with 280 nm wavelength, which peaks centered at 488 nm, which is due to the energy transfer between the molecular orbital of the ligand and charge transfer state of the Ce4+ ions. Emission spectra of Sr2CeO4 with different concentration of Dy3+ ions under near UV radiation excitation, shows that intensity of luminescence spectra is found to be affected by Dy3+ ions, and it increases with adding some percentages of Dy3+ ions. The maximum doping concentration for quenching is found to be Dy3+?=?0.2 mol % to Sr2+ions. The observed broad spectrum from 400 to 560 nm is mainly due to CT transitions in Sr2CeO4 matrix and some fractional contribution of transitions between 4F9/2 → 6H15/2 of Dy3+ ions. Secondly the effect of Eu3+ doping at the Sr2+ site in Sr2CeO4, have been studied. The results obtained by doping Eu3+ concentrations (0.2 mol% to 1.5 mol%), the observed excitation and emission spectra reveal excellent energy transfer between Ce4+ and Eu3+. The phenomena of concentration quenching are explained on the basis of electron phonon coupling and multipolar interaction. This energy transfer generates white light with a color tuning from blue to red, the tuning being dependent on the Eu3+ concentration. The results establish that the compound Sr2CeO4 with Eu3+?=?1 mol% is an efficient “single host lattice” for the generation of white lights under near UV-LED and blue LED irradiation. The commission internationale de I’Eclairage (CIE) coordinates were calculated by Spectrophotometric method using the spectral energy distribution of prepared phosphors. 相似文献
10.
Mete Kaan Ekmekçi Mustafa İlhan Arzu Ege Mehmet Ayvacıklı 《Journal of fluorescence》2017,27(3):973-979
Undoped and different concentration Nd3+ doped SrNb2O6 powders with columbite structure were synthesized by molten salt process using a mixture of strontium nitrate and niobium (V) oxide and NaCl-KCl salt mixture as a flux under relatively low calcining temperature. X-ray diffraction analysis results indicated that SrNb2O6 phases found to be orthorhombic columbite single phase for undoped, 0.5 and 3 mol% Nd3+ doping concentrations. Phase composition of the powders was examined by SEM-EDS analyses. Radioluminescence properties of Nd3+ doped samples from UV to near-IR spectral region were studied. The emissions increased with the doping concentration of up to 3 mol%, and then decreased due to concentration quenching effect. There is a sharp emission peak around 880 nm associated with 4F5/2 → 4I9/2 transition in the Nd3+ ion between 300 and 1100 nm. The broad emission band intensity was observed from 400 to 650 nm where the peak intensities increased by increasing Nd3+ doping concentration. All the measurements were taken under the room temperature. 相似文献
11.
Huma Nazli Baig Jagjeet Kaur Saluja D. Harnath A. S. Sai Prasad K. V. R. Murthy 《Journal of fluorescence》2016,26(3):757-768
YAlO3: Sm3+ phosphor has been synthesized by the solid state reaction method with calcium flouride used as a flux. The resulting YAlO3: Sm3+ phosphor was characterized by X-ray diffraction (XRD) technique, Fourier transmission infrared spectroscopy (FTIR), photoluminescence . . PL excitation spectrum was found at 254,332,380,400,407, 603 and 713 nm. Under excitation of UV(713 nm) YAlO3: Sm3+ (0–3 %) broad band emission were observed from 400 to 790 nm with a maximum around 713 nm of YAlO3 host lattice accompanied by weak emission of Sm3+ (4G5/2 – 6H5/2, 6H7/2,6H9/2) transitions. The results of the XRD show that obtained YAlO3: Sm3+ phosphor has a orthorhombic structure. The study suggested that Sm3+ doped phosphors are potential luminescence material for laser diode pumping and inorganic scintillators. 相似文献
12.
A. K. Singh K. Kumar A. C. Pandey O. Parkash S. B. Rai D. Kumar 《Applied physics. B, Lasers and optics》2011,104(4):1035-1041
Hexagonal LaF3:Er3+/Yb3+ phosphor material has been synthesized by chemical precipitation method to obtain high near-infrared to green upconversion
(UC) efficiency. Its thermal, structural and fluorescence properties have been studied. UC emission bands have been observed
up to 315 nm in UV region. The effect of input pump power on the intensities of various emission bands has been studied in
detail and photon avalanche UC mechanism has been identified. On increasing the excitation power, some bands have shown saturation
in intensity. Also, at higher pump intensities two new UC bands were observed and their origin has been discussed. The phosphor
has also been tested for possible UC-based fingerprint detection. 相似文献
13.
Ho3+–Yb3+ co-doped Y2O3 nanocrystals were synthesized by firing hydroxy carbonate precursors. Yb3+-concentration-dependent up-conversion properties of Ho3+ in Y2O3 nanocrystals have been investigated. The relative intensity of up-converted red emission increases more quickly than that of the green and the near-infrared ones with the enhancement of the concentration of Yb3+. It is believed that the energy process 5
S
2 (5F4) (Ho) + 5
I
7 (Ho) →5
I
6 (Ho)+5
F
5 (Ho) plays an important role in the population of the 5
F
5 level of Ho3+. The result indicates that the intensity ratio of the green emission to the red one can be tuned by changing the sensitizer concentration. PACS 78.55.-m 相似文献
14.
Bin Dong BaoSheng Cao ZhiQing Feng XingJun Wang ChengRen Li RuiNian Hua 《中国科学G辑(英文版)》2009,52(7):1043-1046
The Er3+-Yb3+ codoped Al2O3 nanoparticles with an average particle size of about 50 nm have been synthesized by an arc discharge synthesis method. The
green and red up-conversion emissions centered at about 526, 547 and 677 nm, corresponding respectively to the 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+, were detected by a 978-nm semiconductor laser diode excitation. The Annealing has evident effect on the up-conversion emissions
of the samples: The red up-conversion emission is noticeable before annealing; however, the green up-conversion emission becomes
predominant after annealing. The mixture of (Er,Yb)3Al5O12 and α-(Al,Er,Yb)2O3 phases is more favorable for green up-conversion emissions due to an enhancement of the ESA (I) of 4I11/2+a photon→4F7/2 and ET (III) of 2F5/2(Yb3+)+4I11/2(Er3+)→2F7/2(Yb3+)+4F7/2(Er3+) processes. The two-photon absorption up-conversion process is involved in the green and red up-conversion emissions. The
results have proved that arc discharge synthesis is a new promising preparation technology for optical materials.
Supported by National Natural Science Foundation of China (Grant No. 10804015), the Scientific Research Foundation for Doctor
of Liaoning Province (Grant No. 20071095), and the Educational Committee Foundation of Liaoning Province (Grant No. 2008123) 相似文献
15.
This paper reports on the photoluminescence (PL) and time-resolved properties of Ce3+, Eu3+, and Tb3+ in novel LiSr4(BO3)3 powder phosphors. Ce3+ shows an emission band peaking at 420 nm under 350-nm UV excitation. Energy transfer from Ce3+ to Mn2+ takes place in the co-doped samples. Eu3+ shows red emission under near UV excitation. LiSr4(BO3)3:Eu3+ phosphor could be a suitable candidate for phosphor-converted solid state lighting. The luminescence lifetime is 2.13 ms
for Eu3+ in LiSr4(BO3)3:0.001Eu3+. As Eu3+ concentration increasing, the decay curves deviate from exponential behavior. Tb3+ shows the strongest 5D4→7 F5 emission line at 540 nm. Decay curves of 5D4→7 F5 and 5D3→7 F5 emission with different Tb3+ concentrations were also measured. Cross-relaxation process is discussed based on the decay curves. 相似文献
16.
de Moura AP de Oliveira LH Paris EC Li MS Andrés J Varela JA Longo E Rosa IL 《Journal of fluorescence》2011,21(4):1431-1438
Nanorods and nanoplates of Y2O3:Eu3+ powders were synthesized through the thermal decomposition of the Y(OH)3 precursors using a microwave-hydrothermal method in a very short reaction time. These powders were analyzed by X-ray diffraction,
field emission scanning electron microscopy, Fourrier transform Raman, as well as photoluminescence measurements. Based on
these results, these materials presented nanoplates and nanorods morphologies. The broad emission band between 300 and 440 nm
ascribed to the photoluminescence of Y2O3 matrix shifts as the procedure used in the microwave-hydrothermal assisted method changes in the Y2O3:Eu3+ samples. The presence of Eu3+ and the hydrothermal treatment time are responsible for the band shifts in Y2O3:Eu3+ powders, since in the pure Y2O3 matrix this behavior was not observed. Y2O3:Eu3+ powders also show the characteristic Eu3+ emission lines at 580, 591, 610, 651 and 695 nm, when excited at 393 nm. The most intense band at 610 nm is responsible for
the Eu3+ red emission in these materials, and the Eu3+ lifetime for this transition presented a slight increase as the time used in the microwave-hydrothermal assisted method increases. 相似文献
17.
M. G. Nikolic M. S. Rabasovic J. Krizan S. Savic-Sevic M. D. Rabasovic B. P. Marinkovic A. Vlasic D. Sevic 《Optical and Quantum Electronics》2018,50(6):258
In this paper we study the possibility of using the synthesized nanopowder samples of Gd2Zr2O7:Eu3+ for temperature measurements by analyzing the temperature effects on its photoluminescence. The nanopowder was prepared by solution combustion synthesis method. The photoluminescence spectra used for analysis of Gd2Zr2O7:Eu3+ nano phosphor optical emission temperature dependence were acquired using continuous laser diode excitation at 405 nm. The temperature dependencies of line emission intensities of transitions from 5D0 and 5D1 energy levels to the ground state were analyzed. Based on this analysis we use the two lines intensity ratio method for temperature sensing. Our results show that the synthesized material can be efficiently used as thermographic phosphor up to 650 K. 相似文献
18.
Hyppänen I Hölsä J Kankare J Lastusaari M Pihlgren L Soukka T 《Journal of fluorescence》2008,18(6):1029-1034
The up-converting ZrO2:Yb3+,Er3+ nanomaterials were prepared with the combustion and sol–gel methods. FT-IR spectroscopy was used for analyzing the impurities.
The crystal structures were characterized with X-ray powder diffraction and the mean crystallite sizes were estimated with
the Scherrer formula. Up-conversion luminescence measurements were made at room temperature with IR-laser excitation at 977 nm.
The IR spectra revealed the conventional and OH− impurities for the combustion synthesis products. The structure of the ZrO2:Yb3+, Er3+ nanomaterials was cubic except for the minor monoclinic and tetragonal impurities obtained with the sol–gel method. The materials
showed red (650–700 nm) and green (520–560 nm) up-conversion luminescence due to the 4F9/2→4I15/2 and (2H11/2, 4S3/2)→4I15/2 transitions of Er3+, respectively. The products obtained with the combustion synthesis exhibited the most intense luminescence intensity and
showed considerable afterglow. 相似文献
19.
Mustafa İlhan Mete Kaan Ekmekçi Abdullah Demir Halil Demirer 《Journal of fluorescence》2016,26(5):1637-1643
Undoped and PbNb2O6:Eu3+ (1.0 ≤ x ≤ 6.0 mol%) phosphors were synthesized at 1100 °C for 3.5 h by the conventional solid state reaction method. Synthesized PbNb2O6:Eu3+ phosphors were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and Photoluminescence (PL) analyses. The PL spectra showed series of excitation peaks between 350 and 430 nm due to the 4f–4f transitions of Eu3+. For 395.0 nm excitation, emission spectra of Eu3+ doped samples were observed at 591 nm (orange) and 614 nm (red) due to the 5D0 → 7F1 transitions and 5D0 → 7F2 transitions, respectively. PL analysis results also showed that the emission intensity increased by increasing Eu3+ ion content. No concentration quenching effect was observed. The CIE chromaticity color coordinates (x,y) of the PbNb2O6:Eu3+ phosphors were found to be in the red region of the chromaticity diagram. 相似文献
20.
以EDTA为络合剂,用水热法合成了Er3+,Tm3+和Yb3+共掺杂的NaYF4纳米晶。XRD和TEM的结果表明:粒径约为30 nm,属于六方晶系。在980 nm半导体激光器激发下,研究了不同Er3+离子掺杂浓度对Tm3+和Er3+离子上转换发光性能的影响,光强与泵浦功率的双对数曲线表明,474,525,539,650 nm的发射均属于双光子过程,408 nm的发射属于三光子过程。讨论了样品的协作敏化和声子辅助共振能量传递的上转换发光机制。 相似文献