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1.
Self-assembled three-dimensional Yb3+(Ln = Er, Ho, Tm) co-doped Gd2O3 up-converted (UC) phosphors were synthesized by a facile co-precipitation method, and their morphologies and microstructures were investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis. Under the excitation at 980 nm, spectral pure three primary colors red, green and blue (RGB) emissions were respectively achieved in Yb3+/Er3+, Yb3+/Ho3+ and Yb3+/Tm3+ co-doped Gd2O3 phosphors, in which spectral color purities were tuned by adjusting the doping concentration, annealing temperature, excitation power density and the pulse-width of 980 nm laser. These results provide deeper insights into modulating spectral color purities of up-converted emission, and the potential applications of spectrally pure RGB up-converted materials in fingerprint recognition and multi-color printing were also investigated.  相似文献   

2.
The color-tunable up-conversion (UC) emission was observed in ZrO2:Yb3+, Er3+ thin films synthesized on fused silica substrates using a chemical solution deposition method. The crystal structure, surface morphology image and optical transmittance of ZrO2:Yb3+, Er3+ thin films were detected in the matter of Yb3+/Er3+ doping content. Under excitation by 980?nm infrared light, intense UC emission can be obtained from ZrO2:Yb3+, Er3+ thin films. Photoluminescence study shows that there are two emission bands centered at 548?nm and 660?nm in the UC luminescence spectra, which can be owing to (2H11/2,4S3/2)→4I15/2 and 4F9/24I15/2 transitions of Er3+ ions, respectively. In addition, the color coordinate of UC emission between green-red can be tuned by properly adjusting the dopant concentration, because the composition of Yb3+/Er3+ affect the red/green ratio via the process of cross relaxation and energy back transfer. Our study suggests that ZrO2:Yb3+, Er3+ thin films can be considered as promising materials for new photoluminescence devices.  相似文献   

3.
Multicolor tunable upconversion luminescence materials could be applied to polychromatic LED and anti-counterfeit due to their superiority in abundant color and security feature. However, the harsh terms to achieve emission tuning associated with the drawbacks, including changing the concentration or types of doping ions, higher temperature, and higher excitation power, limit the range of its application. In this paper, a convenient and versatile approach for multicolor-emitting is realized via simply lower power modulating in TiO2:Yb3+/ Er3+ and TiO2: Yb3+/Er3+/Tm3+. The emission color is tuned from pink to yellowish green in TiO2:Yb3+/ Er3+ and tuned from white to yellowish green in TiO2: Yb3+/Er3+/Tm3+. It's found that there is no apparent temperature variation at lower power. Meanwhile, the mechanism of the emission and the multicolor tunability is discussed.  相似文献   

4.
Garnet-type Li6Ca(La0.97Yb0.02RE0.01)2Nb2O12 (RE = Ho, Er, Tm) new phosphors were successfully synthesized via solid reaction at 900°C for 5 hours, whose course of phase evolution, macroscopic/local crystal structure and up-/down-conversion (UC/DC) photoluminescence were clarified. Mechanistic study and materials characterization were attained via XRD, Rietveld refinement, DTA/TG, electron microscopy (FE-SEM/TEM), and Raman/reflectance/fluorescence spectroscopies. The phosphors were shown to exhibit UC luminescence dominated by a ~ 553 nm green band (5F4/5S2 → 5I8 transition) for Ho3+, a ~ 568 nm green band (4S3/2 → 4I15/2 transition) for Er3+ and a ~ 806 nm near-infrared band (3H4 → 3H6 transition) for Tm3+ under 978 nm laser excitation, with CIE chromaticity coordinates of around (0.31, 0.68), (0.38, 0.60) and (0.17, 0.24), respectively. Analysis of the pump-power dependence of UC intensity indicated that all the emissions involve a two-photon mechanism except for the ~ 486 nm blue emission of Tm3+ (1G4 → 3H6), which requires a three-photon process. The DC luminescence of these phosphors is featured by dominant bands at ~ 553 nm for Ho3+ (green, 5F4/5S2 → 5I8 transition), ~568 nm for Er3+ (green, 4S3/2 → 4I15/2 transition) and ~ 464 nm for Tm3+ (blue, 1D2 → 3F4 transition). The UC and DC properties were also comparatively discussed.  相似文献   

5.
The nanocrystalline single-phase Er3+-doped Yb3Ga5O12 garnets have been prepared by the sol-gel combustion technique with a crystallite size of ≈30 nm. The presence of Yb3+ in garnet hosts allows their efficient excitation at the ≈977 nm wavelength. The Er3+ doping of Yb3Ga5O12 garnet host results in deep red Er3+: 4F9/2 → 4I15/2 upconversion photoluminescence (UCPL) emission. The dominance of the red UCPL emission over the green Er3+: 4F7/2/2H11/2/4S3/2 → 4I15/2 component was investigated using the measurement of the steady-state and time-dependent Er3+ and Yb3+ emission spectra in combination with the power-dependent UCPL emission intensity. The proposed upconversion mechanism is discussed in terms of the Er3+ → Yb3+ energy back transfer process as well as Yb3+(Er3+) → Er3+ energy transfer and Er3+ ↔ Er3+ cross-relaxation processes. The studied Er3+-doped Yb3Ga5O12 garnet may be utilized as a red upconversion emitting phosphor.  相似文献   

6.
Fluorescent materials have been widely used for anti-counterfeiting of important documents and currencies, wherein their anti-counterfeit abilities could be improved through multi-mode excitation. Herein, dual-mode-excited double-colour-emitting Er3+doped SrBi4Ti4O15 up-conversion (UC) phosphors (SBTO: Er3+) were synthesised, and their UC spectra included green (2H11/2/4S3/2 → 4I15/2) and red (4F9/2 → 4I15/2) emissions from Er3+ ions under 980 or 1550 nm excitation. However, the green emission colour of phosphors was independent of dopant concentration under 980 nm laser irradiation; whereas the final emission colour was dominated by red emission and significantly affected by contents of Er3+ under 1550 nm excitation. These observations demonstrated potential application in dual-mode double-colour anti-counterfeiting. The possible UC mechanisms and emission characteristics of the phosphors using different 980 and 1550 nm irradiation source were contrastively investigated, and some fluorescent security patterns were also designed to demonstrate the potential applications in anti-counterfeiting and concealing important information.  相似文献   

7.
Up-conversion luminescent (UCL) materials are excellent candidate for optical anti-counterfeiting and the exploitation of multi-wavelength NIR light triggered UC phosphors with tunable color emission is essential for reliable anti-counterfeiting technology. Herein, a series of lanthanide ions (Er3+, Er3+–Ho3+, and Yb3+–Tm3+) doped BaTiO3 submicrometer particles are synthesized through a modified hydrothermal procedure. XRD and SEM measurements were carried out to identify the structure and morphology of the samples and their UCL properties under 808, 980, and 1550 nm NIR excitation are investigated. Er3+ singly doped sample exhibits Er3+ concentration-dependent and excitation wavelength-dependent emission color from green to yellow and orange. The corresponding UC mechanisms under three NIR light excitation are clarified. Pure red emission under 1550-nm excitation was obtained by introducing small amount of Ho3+ and the fluorescent lifetime test was used to confirm the energy transfer from Er3+ to Ho3+. In addition, Yb3+–Tm3+ co-doped sample shows intense blue emission from 1G4 → 3H6 transition of Tm3+ under 980-nm excitation. As a proof of concept, the designed pattern using phosphors with red, green, and blue three primary color emissions under 1550, 808, and 980 nm NIR excitation was displayed to demonstrate their anti-counterfeiting application.  相似文献   

8.
Transparent glass ceramics containing YF3 nano-crystals were fabricated by heat treatment of the SiO2–Al2O3–NaF–YF3–LnF3 (Ln = Er, Yb) glasses. X-ray diffraction and transmission electron microscopy analyses evidenced the homogeneous distribution of spherical YF3 nano-crystals sized 25–30 nm among the glassy matrix. Energy dispersive X-ray spectroscopy measurement, combined with the Stark splitting of the absorption and emission bands, verified the incorporation of Er3+ and Yb3+ ions into YF3 nano-crystals. The infrared to visible up-conversion emission of Er3+ intensified with the increasing of Yb3+ concentration, ascribing to the increase of the efficiency of non-radiative energy transfer from Yb3+ to Er3+ which exceeded 45% for the 0.5Er3+/1.0Yb3+ co-doped sample. The up-conversion luminescence at 545 and 660 nm were affirmed coming from two-photon excitation process.  相似文献   

9.
Series of UV excited Ba3Lu(PO4)3:Tb3+,Mn2+ phosphors with tunable green to red emissions had been prepared using solid state reactions. Powder X-ray diffraction and Rietveld structure refinement were used to investigate the phase purity and crystal structure of the prepared samples. Under UV excitation, the Ba3Lu(PO4)3:Tb3+,Mn2+ samples exhibited not only the typical Tb3+ emission peaks but also the broad emission band of Mn2+ ions due to the efficient Tb3+→Mn2+ energy transfer which had been verified by luminescence spectra and decay curves. Utilizing the Inokuti-Hirayama model, the Tb3+→Mn2+ energy transfer mechanism was determined to be the electronic dipole–quadrupole interaction. Moreover, the emission spectra of Ba3Lu(PO4)3:0.80Tb3+,0.015Mn2+ sample at different temperatures manifested that our prepared phosphors possessed good thermal stability. The luminescence properties investigation results revealed the potential value of Ba3Lu(PO4)3F:Tb3+,Mn2+ in application for UV excited phosphor converted white light emitting diodes.  相似文献   

10.
In the paper, the upconversion luminescence of 70GeO2–30[Ga2O3–BaO–Na2O] glass system co-doped with Yb3+/Tm3+ ions was investigated. Strong blue emission at 478 nm corresponding to the transition 1G4 → 3H6 in thulium ions was measured under the excitation of 976-nm diode laser. The dependence of the upconversion emission upon the thulium ion concentration was studied to determine the optimal conditions of energy transfer between energy levels of active dopants. The most effective energy transfer Yb3+ → Tm3+ was obtained in glass co-doped with molar ratio of dopant 0.7 Yb2O3/0.07 Tm2O3. The increase in thulium concentration more than 0.07 mol% results in the reverse energy transfer from Tm3+ → Yb3+, which leads to rapid quenching of the luminescence line at the wavelength 478 nm. In germanate glass co-doped with 0.7Yb2O3/0.07Tm2O3, the longest lifetime of 1G4 level equal 278 μs was achieved. The presented results indicate that elaborated germanate glass co-doped with Yb3+/Tm3+ ions is a promising material that can be used to produce fiber lasers and superluminescent fiber sources generating radiation in the visible spectrum.  相似文献   

11.
The 3 new upconversion (UC) phosphors of La2O2SO4:RE/Yb (RE=Ho, Er, and Tm, respectively) were derived via facile dehydration of their layered hydroxide precursors that were hydrothermally synthesized at 100°C. Rietveld XRD refinement found contracting cell dimension with decreasing RE3+ size, confirming the direct crystallization of solid solution. The Er3+ and Ho3+ activators both exhibited simultaneous green and red (dominant) emissions under 978‐nm near‐infrared (NIR) laser excitation (NIR‐Vis UC). Particularly, Tm3+ produced a Gaussian‐shaped pure NIR emission band at ~812 nm via its 3H4 → 3H6 transition (NIR‐NIR UC), which is highly desired for NIR biological application. Analysis of the excitation‐power dependent UC properties manifested a 3‐photon mechanism for the 3 phosphors, and the possible photon reactions leading to UC were illustrated.  相似文献   

12.
We have developed a new broadband-sensitive photon upconversion (UC) material that can be used for transparent ceramic plates mounted on the rear faces of crystalline silicon solar cells. We selected the host material of a cubic crystal structure codoped with Er3+ and Ni2+ so that the Ni2+ dopants were fully activated to sensitize the Er3+ emitters. In garnet-type Ca3Ga2Ge3O12 with additional codopants of Nb5+ and Li+ for charge compensation, all the Ni2+ dopants occupied the six-coordinated Ga3+ sites, leading to highly efficient energy transfer from the Ni2+ to the Er3+. Formation of four-coordinated Ni2+ that quenches the UC emission of the Er3+ was prevented, because Ni2+ cannot substitute the four-coordinated Ge4+ much smaller than Ni2+. Consequently, energy dissipation from the Er3+ to the Ni2+ was well reduced compared with the previously developed Gd3Ga5O12:Er,Ni,Nb in which the Ni2+ dopants partially occupied the four-coordinated Ga3+ sites. Additional introduction of Y3+ and Li+ enhanced optical transitions and improved the UC performance, owing to more enhanced lattice distortion, along with eliminating different phases. The optimal composition (Ca0.6Er0.1Y0.1Li0.2)3(Ga0.98Ni0.01Nb0.01)2Ge3O12 exhibited a broadband sensitivity ranging from 1.1 μm (the absorption edge of silicon) to 1.6 μm for the UC emission at 0.98 μm.  相似文献   

13.
This paper reports the luminescent response upconversion of zirconium oxide (ZrO2) nanoparticles doped with erbium (Er3+) and ytterbium (Yb3+) ions, synthesized by hydrothermal route. X ray diffraction (DRX) showed that the synthesized material presents the face centered cubic (FCC) structure. High resolution transmission electron microscopy (HRTEM) showed the presence of crystals size smaller than 10 nm. The photoluminescent analysis allowed to observe an intense upconversion luminescence emission of the samples doped with both ions Er3+ and Yb3+, when these are excited with 910 nm laser source, showing the electronic transitions 4F9/24I5/2; 2H11/24I5/2; 4S3/24I15/2 of Er3+. Two decay times were observed, whose behavior can be associated to the average distance between erbium ions within the nanocrystals.  相似文献   

14.
Li+-ion codoped NaYF4: Er3+/Yb3+ phosphors (β-NaYF4) with a hexagonal structure were synthesized via a modified solid-state route. High-speed planetary ball milling and solid-liquid mixing were simultaneously used to overcome the drawbacks of high synthesis temperatures in conventional routes. A pure β-NaYF4 phase was obtained through calcination at 600?°C for 3?h. Increases in the codoping content of Li+ ion caused a slight shift in X-ray diffraction peak positions toward high angles owing to the distortion of the local crystal field. Field emission scanning electron microscope images showed agglomerated spherical particles of approximately 0.7?µm with narrow size distribution. The upconversion properties of β-NaYF4 codoped with Li+-ion were explored. Two emission bands in the green regions (520?nm and 545?nm) and one emission band in the red region (615?nm) were observed owing to the 2H11/24I15/2, 4S3/24I15/2, and 4F9/24I15/2 transitions of Er3+, respectively. Codoping with 6?mol% Li+ increased the upconversion intensity by three times, which was explained using the energy level diagram. The present phosphors with improved upconversion properties were utilized for latent fingerprint detection on smooth surfaces of regularly used polymer sheets, glass substrates, and compact discs. Using the present phosphors, the base elements with three-level features, such as sharp ridges, valleys, ridge flow, bifurcation, ridge shapes, and dots, were observed on all hydrophilic and hydrophobic surfaces. The prepared phosphors exhibited promising characteristics to detect the features of fingerprint impression for individual identification in forensic applications.  相似文献   

15.
《Ceramics International》2022,48(24):36347-36357
Er3+ and/or Cr3+ doped transparent ZnGa2O4 glass-ceramics were successfully obtained by one-step heat treatment. The results showed that Er3+ ions can enrich around ZnGa2O4 crystal to reduce the crystallization activation energy and promote the growth of ZnGa2O4 crystal. Cr3+ ions may successfully occupy the Ga3+ sites in the ZnGa2O4 lattice but will increase crystallization activation energy and inhibit the growth of the ZnGa2O4 crystal. Before and after crystallization, the coordination-field intensity of Cr3+ ions increased from 2.17 to 2.86, resulting in the peak position of its emission spectra moving from 850 to 688 nm. By excitation at 378 nm, the precursor glass co-doped with Er3+ and Cr3+ ions only showed the characteristic emission peaks belonging to Er3+ ions. After heat treatment, the characteristic emission peaks belonging to Er3+ and Cr3+ ions existed simultaneously, and the emission color changed from green to yellow. By excitation at 980 nm, there were only characteristic emission peaks belonging to Er3+ ions of the Er3+/Cr3+ co-doped glasses before and after heat treatment. The results showed that the Er3+ and/or Cr3+ doped ZnGa2O4 glass-ceramics have adjustable luminescence ability and show potential application value in the field of luminescence display.  相似文献   

16.
Transparent SiO2 - Al2O3 - Na2O - CaO - BaF2 - YbF3 glass ceramics (GC) doped with Er3+ ions were successfully fabricated by a melt-quenching technique with subsequent heat treatment. The formation of BaYbF5 nano-crystalline phase was confirmed by X-ray diffraction and transmission electron microscopy. Compared to the precursor glass (PG), the clearer Stark splitting and greatly enhanced up-conversion (UC) emission in GC indicate that Er3+ ions mainly enter into BaYbF5 nanocrystals with low phonon energy after crystallization. The temperature dependent on purple UC emission ratio (which is due to the Er3+ 4G11/24I15/2 and 2H9/24I15/2 transitions) and common green UC emission ratio with low-power excitation in BaYbF5 GC have been studied respectively. In addition, the UC mechanisms in PG and GC are illustrated and analyzed. The outstanding properties of Er3+-doped BaYbF5 transparent GC may present potential applications in all-solid-state UC lasers and optical fiber temperature sensors.  相似文献   

17.
《Ceramics International》2016,42(4):4642-4647
Tunable up-conversion luminescent material KY(MoO4)2: Yb3+, Ln3+ (Ln=Er, Tm, Ho) has been synthesized by a typical hydrothermal process. Under 980 nm laser diode (LD) excitation, the emission intensity and the corresponding luminescence colors of KY(MoO4)2: Yb3+, Ln3+ (Ln=Er, Tm, Ho) have been investigated in detail. The energy transfer from the Yb3+ sensitizer to Ho3+, Er3+ and Tm3+ activators plays an important role in the development of color-tunable single- phased phosphors. The emission intensity keep balance through control of the Ho3+ co-doping concentrations, white light was experimentally shown at KY(MoO4)2: 20 mol% Yb3+, 0.8 mol% Er3+, 0.5 mol% Tm3+, 1.0 mol% Ho3+ phosphor with further calcination at 800 °C for 4 h under 980 nm laser excitation. The color tunability, high quality of white light and high intensity of the emitted signal make these up-conversion (UC) phosphors excellent candidates for applications in solid-state lighting.  相似文献   

18.
Upconversion Sr2(Gd.98-xEr.02Ybx)8Si6O26 (SGSO:2Er3+/xYb3+) phosphor materials were synthesized using a citrate sol-gel process. X-ray diffraction patterns confirmed their hexagonal structure. Field emission scanning electron microscopy images of SGSO:2Er3+/xYb3+ phosphors depicted submicron particles. The enhanced upconversion luminescence properties of SGSO:2Er3+/xYb3+ phosphors were analysed as a function of Yb3+ ion concentration and laser power. The energy transfer induced enhanced emission of the Er3+/ Yb3+ ions co-doped SGSO phosphors was ascribed to multi-phonon relaxation. The calculated chromaticity coordinates of the SGSO:2Er3+/xYb3+ phosphors showed emissions could be tuned by changing Yb3+ ion concentration. Optimized sample exhibited the chromaticity coordinate values near to the ultra-high definition television standard green emission coordinates.  相似文献   

19.
Highly transparent polycrystalline Er3+:Y3Al5O12 (Er:YAG) ceramics with different Er3+ ions content from 1% to 90% were prepared by the solid-state reaction and the vacuum-sintering technique. The grain boundary is clean and narrow with a width of about 1 nm. The best sintering temperature of the ceramics is about 1800 °C. The relationships between fabrication, microstructure and transparency of the ceramics were discussed. Grain size distributions in axial direction of cylinder samples were characterized by electron probe micro-analyzer (EPMA). The luminescence spectra were measured and discussed.  相似文献   

20.
In present work, a series of Eu doped zinc borate, ZnB2O4, phosphors prepared via wet chemical synthesis and their structural, surface morphology, cathodoluminescence (CL) and thermoluminescence (TL) properties have been studied. Phase purity and crystal structure of as-prepared samples are confirmed by X-ray diffraction measurements (XRD) and they were well consistent with PDF card No. 39-1126, indicating the formation of pure phase. The thermoluminescence (TL) behaviors of Eu activated ZnB2O4 host lattice are studied for various beta doses ranging from 0.1 to 10?Gy. The high-temperature peak of Eu activated sample located at 192?°C exhibited a linear dose response in the range of 0.1–10?Gy. Initial rise (IR) and peak shape (PS) methods were used to determine the activation energies of the trapping centres. The effects of the variable heating rate on TL behaviour of Eu activated ZnB2O4 were also studied. When excited using an electron beam induced light emission (i.e cathodoluminescence, CL) at room temperature (RT), the as-prepared phosphors generate reddish-orange color due to predominant emission peaks of Eu3+ ions located at 576–710?nm assigned to the 5D07FJ (J=1,2,3, and 4) transitions. The maximum CL intensity for Eu3+ ions at 614?nm with transition 5D07F2 was reached Eu3+ concentration of 5?mol%; quenching occurred at higher concentrations. Strong emission peak for Eu3+ ions at 614?nm with transition 5D07F2 is observed. The CL experimental data indicate that ZnB2O4:Eu3+ phosphor as an orange-red emitting phosphor may be promising luminescence materials for the optoelectronic applications.  相似文献   

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