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Photoluminescence Characteristics of Sm3+-doped LnBWO6 (Ln=La, Gd and Y) as New Orange-red Phosphors
摘要： A series of Sm3+-doped LnBWO6 (Ln=La, Gd and Y) phosphors with orange-red light emitting in pure phase were prepared by high temperature solid-state process. The crystal structure, photoluminescence properties, decay lifetimes and thermal stability properties of those as-prepared samples were investigated. Those phosphors can be efficiently excited by near-UV and blue light and emitted orange-red luminescence with color coordinates (0.622, 0.377). Among those LnBWO6 (Ln=La, Gd and Y) hosts, the emission intensities of Sm3+-doped LaBWO6 are the strongest ones. The optimum doping concentration and critical energy transfer distance of Sm3+ ions in LaBWO6 were determined. The fluorescence concentration quenching mechanism was attributed to the dipole-dipole interaction between the Sm3+ ions. The fluorescent thermal quenching studies showed Sm3+ doped LaBWO6 had high thermal-stable properties. The present work suggested that Sm3+-doped LnBWO6 (Ln=La, Gd and Y) as orange-red phosphors exhibited potential application in white LED.
关键词： red phosphors,concentration quenching,energy transfer,white LEDs,luminescent properties
更新于2025-09-23 15:22:29
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Near White Light Emission and Concentration Quenching of Calcium Titanate Doped with Dysprosium (III) Phosphors
摘要： This paper reports the preparation of CaTiO3 doped with various concentrations of Dysprosium (II) using solid state reaction technique. X-ray diffraction patterns of the sample were taken. Observed XRD pattern was matched using software match2!. The pattern was matched significantly with the crystallographic open database card (COD – 96-101-1212) which is a standard card for CaTiO3. This matching exhibited that, the prepared sample is cubic in structure with space group P m ? 3 m (221). Photoluminescence (PL) studies of the samples were also done. PL intensity was found increasing with increasing dopant concentration and maximum intensity was noted at 2.0 mol% concentration of Dy3+, thereafter concentration quenching occurred. Emission Peaks were centered at 483 nm (4F9/2?6H15/2) and 576 nm (4F9/2?6H13/2) respectively. For studying the concentration quenching, the critical distance for energy transfer and electric multipolar character were estimated. The value of multipolar character expressed that, the transition in emission spectra is a dipole – dipole (d-d) transition. Commission Internationale de l’éclairage (CIE) coordinates was found as (0.36, 0.39), which is near to white light. Colour Correlated Temperature (CCT) was 4489 K which was indicative of cool appearance of the light emitted.
关键词： White LED,Concentration quenching,Photoluminescence
更新于2025-09-23 15:22:29
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Ultrathin Y <sub/>2</sub> O <sub/>3</sub> :Eu <sup>3+</sup> nanodiscs: spectroscopic investigations and evidence for reduced concentration quenching
摘要： Here, we report the synthesis and spectral properties of ultrathin nanodiscs (NDs) of Y2O3:Eu3+. It was found that the NDs of Y2O3:Eu3+ with a thickness of about 1 nm can be fabricated in a reproducible, facile and self-assembling process, which does not depend on the Eu3+ concentration. The thickness and morphology of these NDs were determined with small angle x-ray scattering and transmission electron microscopy. We found that the crystal field in these nanoparticles deviates from both the cubic and monoclinic characteristics, albeit the shape of the 5D0 → 7FJ (J = 0, 1, 2) transitions shows some similarity with the transitions in the monoclinic material. The Raman spectra of the non-annealed NDs manifest various vibration modes of the oleic acid molecules, which are used to stabilise the NDs. The annealed NDs show two very weak Raman lines, which may be assigned to vibrational modes of Y2O3 NDs. The concentration quenching of the Eu3+ luminescence of the NDs before annealing is largely suppressed and might be explained in terms of a reduction of the phonon density of states.
关键词： nanodiscs,small angle x-ray scattering,europium-doped yttrium oxide,Raman spectroscopy,concentration quenching,transmission electron microscopy,luminescence
更新于2025-09-23 15:21:21
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Luminescence declining behaviors in YAG:Ce transparent ceramics for high power laser lighting
摘要： High lumen-density laser lighting has become an advanced lighting technology. However, as an important component, transparent light-conversion materials exhibit low efficiency and luminescence declining behaviors, especially under high power density lasers, seriously restricting their potential applications. Herein, high quality YAG:Ce transparent ceramics (TCs) with different Ce concentrations and sizes were designed and fabricated for comparison with YAG:Ce single crystals to reveal the nature behind the above phenomena under the assistance of different encapsulated models of LED/LD devices. The highest luminous efficiency for the TCs of over 248 lm W?1 was achieved in the LED device, while only 170 lm W?1 could be reached for the LD devices. The strong thermal quenching and concentration quenching worked synergistically to result in the luminescence declining behavior in the 0.5 at% YAG:Ce ceramics, which have 80% and 20% responsibility after smart experimental comparison, respectively. Besides, the potential factors for the low efficiency in TC-based LD lighting were also revealed. Therefore, this work not only shows the optical performance of TCs in LED and LD applications, but also presents how the deep influence factors and excitation models lead to differences in their performance. It significantly reinforces the understanding of fundamental problems for TC-based high power laser lighting. These results are crucial for advancing TC-supported technologies in illumination, projection and scintillation.
关键词： transparent ceramics,concentration quenching,laser lighting,YAG:Ce,luminescence declining,thermal quenching
更新于2025-09-16 10:30:52
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Development of all-fiber Fabry-Perot pulse laser with a fiber type saturable absorber and improvement of the oscillation characteristics
摘要： The authors developed high-concentration erbium doped fiber as a saturable absorber, making use of its concentration quenching. Then, they developed an all-fiber Fabry-Perot pulse laser with high-concentration erbium doped fiber and demonstrated that it enables stable and passive pulse oscillation regardless of disturbance. Furthermore, they successfully improve power efficiency and shortening pulse width to 1.8 μs by optimizing the structure of the fiber laser.
关键词： Er doped fiber,fiber laser,concentration quenching,all-fiber passive Q-switching,fiber-type saturable absorber
更新于2025-09-12 10:27:22
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Interfacial Energy Transfer in Hollow Double-Shelled TiO <sub/>2</sub> : <i>x</i> %Eu <sup>3+</sup> @SiO <sub/>2</sub> : <i>y</i> %Tb <sup>3+</sup> Nanospheres for Tissue Imaging
摘要： In this paper, hollow double-shelled TiO2:x%Eu3+@SiO2:y%Tb3+ nanospheres (C1-Ti-x/Si-y) were fabricated using carbon spheres as hard template followed by a two-step sol-gel coating process. The results demonstrate that there is strong interaction between inner TiO2 layer and outer SiO2 layer, which can be characterized by the high surface content of Ti-O-Si bonds. The strong interaction makes it possible to achieve efficient energy transfer from Tb3+ to Eu3+ ions through crossing the double-shelled interface. The interfacial energy transfer (IET) efficiency from Tb3+ to Eu3+ions is strongly influenced by the doping concentration of Eu3+ ions whose maximum is determined to be 30.2%. Furthermore, the surface of inner TiO2 layer is modified by the outer SiO2 layer through this strong interaction, which significantly enhances the emission intensity and suppresses the concentration quenching of Eu3+ ions. Under 377 nm excitation, C1-Ti-x/Si-y simultaneously exhibits red and green emissions derived from Eu3+ and Tb3+ ions, respectively. Moreover, by varying doping concentration of Tb3+ and Eu3+ ions, the luminescence color of the samples can be tuned from green to orange and red. The characterization results show that our proposed phosphors may provide potential applications in tissue imaging.
关键词： Multicolor phosphors,Hollow double-shelled nanostructure,Interfacial energy transfer,Concentration quenching suppressed,Surface modification
更新于2025-09-11 14:15:04
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Dinuclear Eu(III) complexes with macrocyclic tetraphosphine tetraoxide ligand and their photoluminescence properties
摘要： Dinuclear Eu(III) complexes with macrocyclic tetraphosphine tetraoxide ligand (1, 5, 9, 13-Tetraphosphacyclohexadecane-1, 5, 9, 13-tetraphenyl-1, 5, 9, 13-tetraoxide) that keep the Eu(III) ions apart were synthesized and their photoluminescence properties were investigated. It was found that quantum yield of Eu(III) complex 2 in ethyl acetate was excellent (? =0.54) even at a large concentration (1×10?3 mol/l) and strong photoluminescence was obtained. Macrocyclic TPTO ligand has a function of a “separator” of Eu(III) ions that prevents concentration quenching in the Eu(III) complexes.
关键词： Photoluminescence intensity,Quantum yields,Concentration quenching,Macrocyclic tetraphosphine tetraoxide ligand,Europium complex
更新于2025-09-04 15:30:14