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White light emitting thermally stable bismuth phosphate phosphor Ca <sub/>3</sub> Bi( <scp>PO</scp><sub/>4</sub> ) <sub/>3</sub> :Dy <sup>3+</sup> for solid state lighting applications
摘要： White light emitting dysprosium doped Ca3Bi(PO4)3 phosphor was successfully synthesized via co-precipitation method for the first time and the structural, vibrational, morphological and luminescent properties have been investigated for solid state lighting applications. The X-ray diffraction (XRD) and structural refinement studies reveal that the synthesized phosphors consist of single phase with cubic structure. The field emission scanning electron microscopy (FE-SEM) images reveal that the as-synthesized phosphor has micron size with an irregular shape. Under near ultraviolet (n-UV) and blue excitation, the phosphor exhibits white light emission via a combination of blue (~451 nm) and yellow (~575 nm) emission bands. The optimized concentration of Dy3+ ions is 6.0 mol % after which the concertation quenching takes place. The process of energy transfer between Dy3+ ions is due to dipole-dipole interaction, which was confirmed by applying Dexter and Reisfeld’s Energy Transfer (ET) formula. The CIE chromaticity coordinates for the optimized phosphor were (0.329, 0.377), which lie in the white light region. The emission intensity remains to 83.41% at 373 K to that of at room temperature, which indicates good thermal stability. The above mentioned results demonstrate that Ca3Bi(PO4)3 is a potential phosphor for solid state lighting applications.
关键词： White LEDs,Structural and luminescent properties,White light emission,Phosphor,Thermally stable
更新于2025-11-21 11:18:25
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Luminescent Composites Based on Tetrafluoroethylene Copolymer Porous Films Produced by the Diffusion Embedding of Semiconductor Nanoparticles in a Supercritical Medium
摘要： A method for creating film composites based on a new material—a fibrous copolymer of tetrafluoroethylene and vinylidene fluoride—using the diffusion embedding of ready-made nanoparticles into a porous matrix in a supercritical (SC) carbon dioxide medium is developed. The method of cold or hot pressing of impregnated porous films was used at the final stage of creation of such composites. The peculiarities of the effect of the supercritical fluid treatment of porous copolymer films on the surface structure of pressed films are discussed. Luminescent composites with semiconductor nanoparticles of cadmium selenide and nanocrystalline silicon are obtained; their radiation covers a range of 500–1000 nm. The change in the luminescence properties of the resulting nanocomposites under the action of excitation laser radiation at 405 nm is demonstrated.
关键词： cadmium selenide,film composite,fibrous matrix,luminescent properties,diffusion embedding,nanocrystalline silicon
更新于2025-11-14 15:30:11
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Gas adsorption and Fluorescent Sensing Properties of Three Metal-Organic Frameworks Based on 3,5-di(2’,5’-dicarboxylphenyl)benozoic Acid and Cadmium Ions
摘要： Three 3D Cd(Ⅱ) metal-organic frameworks(MOFs), namely, {[Cd3(L)(OH)(H2O)3]n·2H2O} (1), {Cd5(L)2(H2O)9}n (2) and {Cd2(L)(bib)(NH4)}n (3), have been synthesized based on H5L and cadmium ion under hydrothermal conditions (H5L = 3,5-di(2’,5’-dicarboxylpyl)benozoic acid, bib = 1,4-bis(1-imidazoly)benzene), and characterized by IR spectrum analysis, powder X-ray diffraction analysis (PXRD) and thermogravimetric analysis (TGA). X-ray single crystal diffraction analyses showed that complex 1 is a porous 3D 4-connected net with the point symbol of {4.65} with the trinuclear [Cd3(OH)(COO)5] SBUs, complex 2 displays a 3D framework 7-connected net with the point symbol of {33.412.55.6} with the pentanuclear [Cd5(COO)10(H2O)9] SBUs and complex 3 presents a porous 3D 4,6-connected net with the point symbol of {43.610.82}{43.63}. Furthermore, fluorescent measurements indicated that 1 and 2 have potential application in the detection for Fe3+, CrO4 2- and Cr2O7 2- ions in aqueous solution. Gas sorption properties exhibited that complex 1 has better hydrogen storage performance.
关键词： Luminescent properties,3,Gas adsorption,5–di(2’,5’-dicarboxylphenyl)benozoic acid
更新于2025-09-23 15:23:52
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Enhanced luminescent properties of Tb3+-doped transparent oxyfluoride glass-ceramics containing YF3 nanocrystals
摘要： Tb3+-doped transparent oxyfluoride glass-ceramics (GC) containing YF3 nanocrystals have been fabricated via a traditional melt-quenching route with appropriate thermal-treatment. The microstructural, luminescent and optical properties of the synthesized material were investigated systematically. The precipitated particles in the glass phase of GC540 are YF3 nanocrystals with a mean size of around 20 nm, which has been confirmed and estimated by XRD and TEM. Compared with the precursor glass (PG), the emission intensity at 545 nm (5D4→7F5) of YF3: Tb3+-doped GC is significantly enhanced (under ultraviolet and X-rays excitation) and the lifetime of GC is longer. It can be confirmed that the preferential enrichment of Tb3+ in the precipitated low-phonon-energy YF3 nanocrystals can effectively reduce non-radiative transitions. The obtained results confirm that such Tb3+-doped YF3 GC might be useful as a novel X-ray scintillating material for slow event detection.
关键词： X-ray excited luminescence spectra,luminescent properties,YF3,Glass-ceramics
更新于2025-09-23 15:22:29
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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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Enhanced long afterglow of SrAl2Si2O8:Eu2+ by codoping Dy3+
摘要： Eu2+/Dy3+ doped SrAl2Si2O8 phosphors were synthesized by a solid state reaction. The phase and luminescent properties of the synthesized phosphors were investigated by the X-ray powder diffraction, photoluminescence spectra, decay curves and the thermo-luminescence glow curves. The XRD results show that the doped Eu2+/Dy3+ has no influence on the phase of SrAl2Si2O8. The incorporation of Dy3+ could significantly enhance the intensity and prolong the afterglow duration of SrAl2Si2O8:Eu2+. The co-doped Dy3+ ions act as trap centers and trap the electrons generated during exposure of the phosphor to an excitation source, which induces the longer afterglow comparing with Eu2+ singly doped SrAl2Si2O8 phosphor.
关键词： SrAl2Si2O8:Eu2+/Dy3+,luminescent properties,long afterglow,phosphors
更新于2025-09-23 15:21:21
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Effect of Concentration on the Spectrala??Luminescent Properties of Quantum Dots in Colloidal Solutions
摘要： The effect the concentration of double-shell CdSe/CdS/ZnS semiconductor colloidal quantum dots has on the measured parameters of the absorption and luminescence spectra of a solutions of these quantum dots in toluene is studied via optical spectroscopy. Possible mechanisms of the effect the concentration of quantum dots in the solutions has on the characteristics of the luminescence spectra are analyzed.
关键词： optical spectroscopy,colloidal solutions,concentration,quantum dots,spectral-luminescent properties
更新于2025-09-23 15:21:01
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Novel red emitting LnTaO4: Eu3+ (Ln = La, Y) phosphors for warm white LEDs
摘要： LnTaO4: Eu3t (Ln ? La, Y) phosphors were synthesized by high-temperature solid-state reaction. Powder X-ray diffraction analysis confirmed the pure phase formation. Diffuse reflection spectra, excitation and emission spectra, the CIE chromaticity coordinates as well as the temperature-dependent emission spectra were investigated those phosphors. Upon near UV and blue excitation LnTaO4: Eu3t (Ln ? La, Y) show intense red emission of Eu3t. The optimum concentration of Eu3t in LaTa1-xEuxO4 phosphor was x ? 0.20, and concentration quenching mechanism was the electric dipole-dipole interaction. Furthermore, the critical transfer distance was obtained and the CIE chromaticity coordinates of LaTaO4: Eu3t samples were close to the National Television System Committee standard values. The temperature-dependent luminescence indicated LaTaO4: Eu3t exhibited moderate thermal stability. Those results suggested that LnTaO4: Eu3t (Ln ? La, Y) as red emitting phosphors could be potential candidates for white LEDs.
关键词： Luminescent properties,Red emitting phosphors,White LED,Thermal stability
更新于2025-09-23 15:19:57
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Improved luminescence properties of a novel red dodec-fluoride phosphor Ba <sub/>3</sub> Sc <sub/>2</sub> F <sub/>12</sub> :Mn <sup>4+</sup> with extraordinary thermal stability for WLED application
摘要： Mn4+-activated red phosphors have recently attracted tremendous attention for their fascinating performance in white light emitting diodes (WLEDs) application to achieve warm white light, while the thermal stability of fluoride is still considered as a drawback. Herein, we report a novel red phosphor composed of Ba3Sc2F12:Mn4+ (BSF:Mn), in which, the emitting centers of Mn4+ ions are locating in the sites of Sc3+ ions. The photoluminescence of BSF:Mn varies with the concentration of K2MnF6, reaction temperature, and the concentrations of NH3·H2O in reaction system. Partly substituting Ba2+ with Ca2+ decreases the luminescent intensity of BSF:Mn. By employing the as-prepared phosphor BSF:Mn as a red component, a high-performance WLED with a correlated color temperature (CCT) at 4796 K and a color rendering index (CRI) of 85.2 was obtained. The phosphor BSF:Mn keeps undecomposed up to 800 oC, therefore, this work exhibits a strategy to explore a novel Mn4+-doped fluoride with particularly thermal stability.
关键词： luminescent properties,thermal stability,Ba3Sc2F12:Mn4+,Mn4+-activated red phosphors,WLEDs
更新于2025-09-19 17:13:59
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Bi-Activated Glasses and their Potential Covering Spectral Region as Active Media for Tunable near Infrared Lasers
摘要： To obtain the near infrared luminescence Bi-activated phosphate-aluminum-natrium glasses were synthesized and treated under reduction conditions. The reduction conditions were achieved by different methods: treatment in graphite atmosphere, hydrogen atmosphere, and X-ray irradiation. The spectral-luminescent properties of glass samples were measured and analyzed. Bi-activated phosphate-aluminum-natrium glasses after reduction treatment have shown wide near infrared luminescence with two peaks at the telecommunication windows region. The nature of the luminescent centers in Bi-activated phosphate-aluminum-natrium glasses are discussed. The spectral-luminescent properties of synthesized glasses were studied at the context of Bi-activated glass as the active media for tunable near infrared lasers operating in 1050-1500 nm region. The demonstrated properties of Bi-activated phosphate-aluminum-natrium glass are promising to fill the gap in near infrared lasers operating range.
关键词： Tunable infrared lasers,near infrared luminescence,Bi-doped glasses,spectral-luminescent properties of bismuth in glass matrix
更新于2025-09-16 10:30:52