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On the Blue Emitting Phosphor Na <sub/>3</sub> RbMg <sub/>7</sub> (PO <sub/>4</sub> ) <sub/>6</sub> :Eu <sup>2+</sup> Showing Ultra High Thermal Stability
摘要： This work concerns a novel blue emitting LED phosphor activated by Eu2+. It turned out that this luminescent material can be efficiently pumped by near UV or UV-A radiation sources while it exhibits a high quantum yield for a doping level between 0.3 and 3.0%. More impressively, the material has a very high quenching temperature T1/2 and will thus be applicable on-chip in high power phosphor converted LEDs or even in laser diodes. The emission and thermal stability is almost identical to that of BAM:Eu2+ while the absorption band is broader and reaches into the near UV range. Therefore, Na3RbMg7(PO4)6:Eu2+ is a promising candidate as a blue emitter in high CRI full conversion LEDs. To investigate the site preference of Eu2+, DFT and Ligand Field Theory based calculations were performed to successfully predict the emission spectrum. An unusual decay behavior was observed at low temperatures and the underlying mechanism involving spin-forbidden transitions of Eu2+ is discussed.
关键词： high thermal stability,solid state lighting,Eu2+ luminescence,near UV LED,high CRI,decay time,Blue photoluminescence
更新于2025-11-21 11:18:25
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Preparation and scintillation properties of Eu2+:CaF2 scintillation ceramics
摘要： Different concentration of Eu2+ -doped CaF2 ceramics, designed to the low (0.01 at% and 0.04 at%) and the high (0.2 at% and 0.5 at%), have been prepared by hot-press sintering method. Under 355 nm laser excitation, all the ceramics showed emission bands at 425 nm due to 5d-4f transitions of Eu2+ ions and weak emission peaks at 574, 617 and 630 nm due to the 4-4f transitions of Eu3+ ions. Under X-rays irradiation, the emission bands at 315 nm and 422 nm, ascribed STE and 5d-4f transitions of Eu2+ ions, were observed and the weak emission peaks, ascribed 4f‐4f transitions of Eu3+ ions, were also observed in all the samples. Furthermore, the scintillation decay lifetime and pulse height spectra of the samples were investigated.
关键词： Photoluminescence,Eu2+:CaF2 ceramics,Radioluminescence,Scintillation
更新于2025-09-23 15:22:29
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A micro-structural corrosion mechanism on the thermal degradation of BaMgAl10O17: Eu2+ phosphor
摘要： The thermal degradation is a vital issue that restricting luminous efficiency and service life of BaMgAl10O17: Eu2+phosphor for chromogenic and illuminating fields. The effects of heat-treatment temperature on the luminescence properties and micro-structure of BAM were researched to accurately elucidate the thermal degradation mechanism. Some pieces of evidence for micro-structural corrosion were detected according to the results of PL, TL, XPS and IR. With the heat-treatment temperature increasing, a decrease of blue-emitting intensity and new red-emitting peaks revealed thermal degradation and activator oxidation. The XPS results showed the surface chemical composition changes and the micro-structure adjustment. The defects elimination detected by TL could be responsible for this micro-structural corrosion. IR results further confirmed the changes on bond forms. These were direct evidence and specific forms for the micro-structural corrosion due to the thermal degradation. Based on the relationship between micro-structural corrosion and luminescence properties, a micro-structural corrosion mechanism was given for the thermal degradation of BAM phosphor. The thermal degradation was caused in parallel by the micro-structure corrosion and the activated ion (Eu2+) oxidation.
关键词： Micro-structural corrosion,Thermal degradation mechanism,BaMgAl10O17:Eu2+,Heat-treatment
更新于2025-09-23 15:22:29
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Synthesis, Structural and Luminescent Properties of Eu2+/Dy3+ Activated GdAlO3 Phosphors by Solid State Reaction Method Under Nitrogen Atmosphere
摘要： Synthesis, Structural and Luminescent Properties of Eu2+/Dy3+ Activated GdAlO3 Phosphors by Solid State Reaction Method Under Nitrogen Atmosphere. Eu2+ and Dy3+ singly doped and codoped GdAlO3 phosphor was synthesized by solid state reaction method in a reducing atmosphere of nitrogen. Samples were characterized by powder X-ray diffraction (PXRD) analysis. The average crystal size was obtained around 48 nm. Surface morphology was verified by scanning electron microscopy (SEM) analysis. The emission spectra of phosphors singly doped with Eu2+ and codoped with Eu2+; Dy3+ respectively were recorded under 354 nm excitation. The emission spectra of Eu2+ has intense emission peak at 515 nm. It was observed that the after codoping with Eu2+ and Dy3+ the emission bands of Eu2+ dominates along with a new emission band centred at 419 nm. CIE chromaticity diagram shows variation in emitted colour with Eu2+, Dy3+ singly doped and codoped phosphor. The investigation of Dy3+ codoping shows the colour tunable behaviour of the phosphor. This colour tunable behaviour of the phosphor makes it useful in the colour display applications.
关键词： CIE,XRD,Eu2+,photoluminescence,GdAlO3,Dy3+
更新于2025-09-23 15:22:29
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Synthesis and mechanoluminescent property of (Eu2+, Dy3+)-co-doped strontium aluminate phosphor by soft mechanochemistry-assisted solid-state method
摘要： (Eu2+, Dy3+)-co-doped strontium aluminate (SrAl2O4:Eu2+, Dy3+) powder as a mechanoluminescent (ML) phosphor was synthesized via soft mechanochemical pretreatment of precursor mixtures in a stirred media mill and subsequent calcination. Effect of soft mechanochemical pretreatment of precursors on the synthesis process as well as the photoluminescent (PL) and ML properties of SrAl2O4:Eu2+, Dy3+ phosphor was investigated. The precursor mixtures unground and ground at different time and the resultant phosphors were characterized by laser particle size analysis, X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, Fourier transfer infrared spectroscopy and optical property measurement. The results reveal that soft mechanochemical pretreatment of precursor mixture promotes the crystal growth, and reduces the subsequent calcination temperature. SrAl2O4:Eu2+, Dy3+ phosphor can be obtained via calcining at 1200 oC for precursor mixture ground at 60 min, but formed via calcining at 1400 oC for unground precursor mixture. The phosphor synthesized with precursor mixture ground at 60 min has the maximum PL and ML intensities due to the enhancement of Eu2+ and Dy3+ ions into the crystal lattice to form more electron traps. The measurements by a designed ML instrument indicate that the ML intensity increases with increasing impact stress, and decreases with multiple applications of the same impact stress on phosphor disks.
关键词： Phosphor,Soft mechanochemistry,(Eu2+, Dy3+)-co-doped strontium aluminate,Solid-state method,Mechanoluminescence
更新于2025-09-23 15:22:29
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Synthesis and Optical Properties of the Eu2+-Doped Alkaline-Earth Metal Hydride Chlorides AE7H12Cl2 (AE = Ca and Sr)
摘要： In our study of the optical properties of Eu2+-doped alkaline-earth metal hydride chlorides AE7H12Cl2 (AE = Ca and Sr) we observe yellow (AE = Sr) and orange-red (AE = Ca) emission. Compared to the emission energies of Eu2+ - doped fluorides, chlorides and mixed fluoride chlorides, this corresponds to a wide redshift of the Eu2+ 4f65d1–4f7 emission. We explain this observation with the strong polarizability of the hydride anion and therefore its strong nephelauxetic effect, which shifts the 5d barycenter to lower energy. Furthermore, the redshift is even significant compared to other known hydride chlorides and hydride oxide chlorides, which is probably caused by the relatively short AE2+/Eu2+?H? distances, or it might also be caused by impurity-trapped exciton states. We have also investigated the temperature dependence of the photoluminescence lifetimes and the thermal stability. Even though the compounds are probably not ideal for phosphor application due to their low stability against air and moisture, our study underlines the large influence of the highly polarizable hydride anion on the optical properties of divalent europium and shows that Eu2+ could be used as a probe in mixed anionic system to determine the hydride content.
关键词： Hydride Chlorides,Eu2+ Luminescence,Alkaline-Earth Metals
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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A K3ScSi2O7: Eu2+ based phosphor with broad-band NIR emission and robust thermal stability for NIR pc-LEDs
摘要： In this work, an Eu2+-doped K3ScSi2O7 (KSSO) NIR phosphor with broad-band NIR emission and robust thermal stability was designed and synthesized successfully. The crystal structure, luminescent properties, the mechanism of abnormal NIR emission, thermal stability and application to NIR pc-LEDs were investigated in detail.
关键词： NIR phosphor,Eu2+-doped,K3ScSi2O7,thermal stability,NIR pc-LEDs,broad-band emission
更新于2025-09-23 15:21:01
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Highly Luminous Ba2SiO4a???′N2/3?′:Eu2+ Phosphor for NUV-LEDs: Origin of PL-Enhancement by N3a??-Substitution
摘要： Ba2SiO4?δN2/3δ:Eu2+ (BSON:Eu2+) materials with different N3? contents were successfully prepared and characterized. Rietveld refinements showed that N3? ions were partially substituted for the O2? ions in the SiO4-tetrahedra because the bond lengths of Si-(O,N) (average value = 1.689 ?) were slightly elongated compared with those of Si-O (average value = 1.659 ?), which resulted in the minute compression of the Ba(2)-O bond lengths from 2.832 to 2.810 ?. The average N3? contents of BSON:Eu2+ phosphors were determined from 100 nm to 2000 nm depth of grain using a secondary ion mass spectrometry (SIMS): 0.064 (synthesized using 100% α-Si3N4), 0.035 (using 50% α-Si3N4 and 50% SiO2), and 0.000 (using 100% SiO2). Infrared (IR) and X-ray photoelectron spectroscopy (XPS) measurements corroborated the Rietveld refinements: the new IR mode at 850 cm?1 (Si-N stretching vibration) and the binding energy at 98.6 eV (Si-2p) due to the N3- substitution. Furthermore, in UV-region, the absorbance of N3?-substituted BSON:Eu2+ (synthesized using 100% α-Si3N4) phosphor was about two times higher than that of BSO:Eu2+ (using 100% SiO2). Owing to the N3? substitution, surprisingly, the photoluminescence (PL) and LED-PL intensity of BSON:Eu2+ (synthesized using 100% α-Si3N4) was about 5.0 times as high as that of BSO:Eu2+ (using 100% SiO2). The compressive strain estimated by the Williamson?Hall (W?H) method, was slightly increased with the higher N3? content in the host-lattice of Ba2SiO4, which warranted that the N3- ion plays an important role in the highly enhanced PL intensity of BSON:Eu2+ phosphor. These phosphor materials could be a bridgehead for developing new phosphors and application in white NUV-LEDs field.
关键词： N3? substitution,Ba2SiO4:Eu2+,IR,PL,SIMS,XPS
更新于2025-09-23 15:19:57
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Efficient Luminescence of Sr2Si5N8:Eu2+ nanophosphor and its film applications to LED and Solar cell as a downconverter
摘要： Here we present the synthesis of the efficient nanophosphor Sr2Si5N8:Eu2+ (D50 = 144 nm) by a simple milling approach, its strong Rayleigh scattering, and its film applications to white LED and silicon solar cell as a downshifting medium. The final nanophosphor product showed the quantum efficiency comparable to the bulk phosphor which is, to our knowledge, the highest record of nitride nanophosphors. Especially the nanophosphor showed the more tail emission at the shorter-wavelength side of the emission spectrum and the faster thermal quenching with the more spectral broadening along with the temperature due to Rayleigh scattering. Also the lowering in the excitation spectrum was observed due to lower absorbance. Finally, the nanophosphor-dispersed polyvinyl alcohol (PVA) film was made, and its applications to white LED and silicon solar cell as a downshifting medium demonstrated that it gave the high color rendering property in white LED in spite of still lower luminous efficiency, and it caused the increase in efficiency of silicon solar cell.
关键词： nanophosphor,white LED,milling,downconverter,solar cell,Sr2Si5N8:Eu2+
更新于2025-09-19 17:13:59