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Eu-Doped BaF2 Nanoparticles for Bioimaging Applications
摘要： Pure Eu3+ ion doped BaF2 nanoparticles with tunable properties or property combinations are accessible via an ionic liquid-assisted solvothermal method. Structural parameters such as cell parameters, lattice strain and especially morphology are judiciously tuned with calcination temperatures. For example, tensile strain is observed in samples calcined up to 400oC, however compressive strain appears in samples calcined at 600oC and beyond. Larger surface area up to the sample calcined at 400oC and observation of layer structure at higher calcinations temperature (650oC and beyond) have been rationalized based on secondary nucleation. 3-dimensional island-like morphology with step-like layer structure caused by secondary nucleation and self-assembly are visualized and explained by Scanning Electron Microscope analysis. Moreover, emission intensity, decay time, quantum yield and Judd-Ofelt parameter of the Eu3+ ions increase systematically with calcinations temperature to a maximum at 400oC, above which they decrease and finally vanish at 800oC. Our results suggest that, smaller sized nanoparticles with 3-dimensional island-like structures, generated due to secondary nucleation at higher calcinations temperature may cause the increase of surface defects and subsequent luminescence quenching. To the best of our knowledge, the interplay between calcinations and secondary nucleation followed by drastic changes in the luminescence properties is new and previously unreported for the nanopowders. In addition, to improve the dispersibility, as-prepared nanoparticles are coated with silica and solubility of nanoparticles is measured in different solvents so that it can be useful for bio-imaging applications also.
关键词： calcination,photoluminescence,rare-earth ion,secondary nucleation,nanoparticles
更新于2025-09-23 15:23:52
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Synthesis and photoluminescent properties of Ba2+ ions doped europium formate phosphors for white light-emitting diodes
摘要： We report on the synthesis and photoluminescent performance of the Ba2+ ions doped Eu(HCOO)3 phosphors as well as their promising applications in indoor illumination. The thermal stability of the synthesized sample with microparticles was characterized by the thermogravimetric analysis. Irradiated by 396 nm light, the unique emissions of Eu3+ ions originating from the 5D0 → 7FJ (J ? 1, 2, 3, 4) transitions were observed. With the aid of the Judd-Ofelt theory, the local symmetry properties of the Eu3+ ions in the selected host were studied, revealing that the sites taken by the Eu3+ ions possessed low symmetry with non-inversion center. An enhanced luminescent intensity was seen in the resultant phosphors when the Ba2+ ions were introduced and the optimal doping content was 10 mol%. The studied samples can exhibit bright visible red emission with high color purity of 93.3% upon 396 nm excitation. Moreover, the resistance of the emission intensity to the temperature was also explored and the activation energy was 0.188 eV. Furthermore, the internal quantum efficiency of the resultant samples was 67% when excited by 396 nm. Ultimately, a light-emitting diode (LED) lamp, which emitted warm white light with high color rendering index of 80.7 and low color correlated temperature of 4715 K, was constructed, indicating the feasibility of the synthesized phosphors for white-LED.
关键词： Phosphors,White-LED,Luminescence,Rare-earth ion
更新于2025-09-23 15:21:01
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Controlled synthesis and panchromatic printing of highly luminescent NaYF4:Ln3+ upconversion hollow microtubes for information encryption on various packaging substrates
摘要： Lanthanide-ion doped β-NaYF4 crystals with bright and tunable upconversion luminescence are urgently demanded in anti-counterfeiting printing. Herein, novel highly luminescent hexagonal NaYF4:Ln3+ upconversion hollow microtubes (UCHMs) were controlled synthesized by a one-pot hydrothermal method employing poly(ethylene imine) (PEI) as ligand. The surface of the synthesized UCHMs was decorated by water-soluble polymer of PEI, rendering the hydrophilic nature of UCHMs. Besides, the synthesized UCHMs exhibited bright upconversion luminescence under the irradiation of a 980 nm laser due to the unique structure and morphology. Time-dependent morphology evolution showed that the formation of UCHMs experience a morphology change from nanoparticles to hexahedron to microprisms, and ultimately to microtubes via a dissolution-reconstruction formation mechanism. Furthermore, the resulting UCHMs were used as pigments for preparation of luminescent inks and their application in anti-counterfeiting printing was explored. To realize panchromatic printing, we prepared three-primary-color (RGB) UCHMs by rational tailoring the doping pairs and molar ratio of the lanthanide ions in UCHMs. Based on the superposition principle of the red-green-blue as three primary colors, a wide array of luminescent inks with panchromatic luminescent colors were prepared. The successful creation of securely light-responsive smart encryption patterns on various packaging substrates such as art paper, aluminum sheet, polyethylene terephthalate (PET) film and cardboard by screen printing was demonstrated. Our strategy provides a new route for controlled synthesis of hydrophilic UCHMs and the as-prepared UCHMs have great potential in application of packaging anti-counterfeiting.
关键词： Rare earth ion-doped NaYF4,Anti-counterfeiting,Hollow microtube,Screen printing,Hydrothermal
更新于2025-09-23 15:19:57
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Structural, Spectroscopic, and Excitonic Dynamic Characterization in Atomically Thin Yb <sup>3+</sup> ‐Doped MoS <sub/>2</sub> , Fabricated by Femtosecond Pulsed Laser Deposition
摘要： The large area deposition and synthesis of 10 mm × 10 mm atomically thin Yb3+-doped MoS2 films by femtosecond pulsed laser deposition on a silica glass optical platform for device applications are demonstrated for the first time. The presence of Yb3+-ion doping is confirmed using photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The Yb3+-doped MoS2 films, when excited with a 976 nm laser, exhibit room temperature PL with a peak at 1002 nm. The XPS and Raman spectroscopic analyses of the Yb3+-doped and undoped films show that the deposited films are a mixture of 2H- and 1T-MoS2 after postdeposition annealing at 500 °C. The density functional theory analysis shows that the 1T phase is metastable by +77 kJ (≈0.8 eV) mol-1, when compared with the 2H state at 0 K. Ultrafast transient nonlinear optical spectroscopic measurements prove that the saturable absorption of undoped MoS2 is significantly modified after Yb3+-ion doping, by displaying dopant-host structure charge transfer. The complex transient absorption line shape shows a combination of bleach (negative) signals at the A (670 nm) and B (630 nm) exciton energies, and a strong induced absorption below the A exciton level. The results presented herein provide critical insight in designing novel rare-earth-ion doped 2D materials and devices.
关键词： molybdenum disulfide,femtosecond pulsed laser deposition,saturable absorber,rare-earth ion photoluminescence,nonlinear optical properties
更新于2025-09-11 14:15:04
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A Novel Rare Earth Ion Fluorescent Probe towards the Trace Detection of 2,4,6-Trinitrotoluene Based on Fluorescence Resonance Energy Transfer
摘要： This paper reports a resonance energy transfer-fluorescence quenching of the core-shell structure of CaMoO4:Tb3+@SiO2 modified by amino group on the surface for the ultrasensitive and ultratrace detection of 2,4,6-trinitrotoluene (TNT) in solution environments. Organic amine was covalently modified onto the surface of silica shell to form a hybrid monolayer of amino group. The particle can specifically bind TNT species by the charge-transfer complexing or acid-base pairing interactions between electron-rich amine ligands and electron-deficient aromatic rings. The resultant TNT-amine complexes bound at the silica surface can strongly suppress the fluorescence emission of the chosen dye by the fluorescence resonance energy transfer (FRET) from CaMoO4:Tb3+ fluorescence donor to the irradiative TNT-amine acceptor through intermolecular polar-polar interactions at spatial proximity. The nanoparticle can sensitively detect down to 1 nM TNT with the use of only 10 μL of solution (2 pg TNT). The simple FRET-based nanoparticle sensors reported here exhibit a high and stable fluorescence brightness, strong analyte affinity and good assembly flexibility and can thus find many applications in the detection of ultratrace analytes.
关键词： Fluorescence quenching,FRET,Ultratrace detection,2,4,6-Trinitrotoluene,Rare earth ion
更新于2025-09-11 14:15:04
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EPR study of luminescence mechanism of Nd3+-doped borate aluminum glass
摘要： The luminescence mechanisms of Nd3+: B2O3-Al2O3-CaO glasses with different amounts of B2O3 were investigated based on their electron paramagnetic resonance spectra and luminescence properties. The results of the echo-detection field sweep exhibited two different maxima indicating that Nd3+ ions occupy two different sites. 27Al and 11B signals in two-dimensional hyper?ne sublevel correlation spectra were observed in the (+, +) quadrant, indicating that both 27Al and 11B are located in the second or higher order Nd3+ coordination shell. In addition, the fraction of the 11B nucleus present in the Nd3+ coordination sphere increased with an increase in the amount of B2O3. The continuous changes in the hypersensitive transition intensity and luminescence properties are strong indicators for the change in the Nd3+ coordination environment.
关键词： 2D-HYSCORE,EPR,rare-earth ion local environment,borate aluminum glass
更新于2025-09-10 09:29:36