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Highly efficient rare-earth-free deep red emitting phosphor La <sub/>2</sub> Li <sub/>1?y</sub> Sb <sub/>1?x</sub> O <sub/>6</sub> : <i>x</i> Mn <sup>4+</sup> , <i>y</i> Mg <sup>2+</sup> : application in high-power warm w-LEDs
摘要： Phosphor-in-glass (PiG), which serves as both a luminescent convertor and organic encapsulation material in high-power white light-emitting diodes (w-LEDs), has become a prospective research hotspot owing to its high transparency and thermal stability. However, YAG:Ce3+ PiG-based LED devices still suffer from a lack of a red component. Therefore, the development of red phosphors with excellent quantum efficiency and superior thermal stability is urgent. Herein, a highly efficient La2Li1?ySb1?xO6:xMn4+,yMg2+ red phosphor with a broadband emission ranging from 670 to 720 nm was fabricated via a conventional solid-state reaction. By co-doping Mg2+ in La2LiSbO6:Mn4+, the emission intensity was enhanced significantly, which reaches as high as 10 times that of the single-doped La2LiSbO6:Mn4+. It is proposed that the Mg2+ dopant can compensate imbalanced charges for the substitution of Sb5+ by Mn4+ and interrupt adverse energy transfer among the Mn4+ activators. Impressively, a maximum quantum yield of up to 80.3% is achieved and about 80% emission intensity is retained at the temperature of 423 K. Furthermore, the crystal field strength (Dq) and Racah parameters (B and C) together with the nephelauxetic ratio (b1) were calculated based on the obtained spectroscopic data. By embedding the red-emitting La2LiSbO6:Mn4+,Mg2+ phosphor and yellow-emitting YAG:Ce3+ phosphor into TeO2-based glass, an inorganic PiG composite as a color converter to replace organic silicone was acquired. The excellent optical parameters and tunable chromaticity feature of the fabricated w-LEDs were achieved by adjusting the mass ratio of La2LiSbO6:Mn4+,Mg2+ to YAG:Ce3+ in the PiG plate, where the correlated color temperature changed from cool white (6555 K) to warm (4130 K) and the color rendering index increased from 73.7 to 86.6 under an operating current of 300 mA.
关键词： Phosphor-in-glass,quantum yield,red phosphor,Mg2+,thermal stability,w-LEDs,Mn4+
更新于2025-11-20 15:33:11
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Novel Ca2GdTaO6:Mn4+,M (M = Li+, Na+, K+, and Mg2+) red phosphors for plant cultivation light-emitting diodes: Synthesis and luminescence properties
摘要： Recently, Mn4+-activated red phosphors are becoming potential color converters for application in indoor plant cultivation light-emitting diodes, owing to their satisfactory luminescence properties as well as low cost. Herein, novel Mn4+-activated double perovskite-type Ca2GdTaO6 phosphors have been synthesized by a high-temperature solid-state reaction method in air, which exhibited a broad excitation band with two peaks locating at 355 nm and 496 nm in range of 250-600 nm and had an intense red emission peaking at 676 nm due to Mn4+:2Eg→4A2g spin-forbidden transition ranging from 650 to 750 nm under 355 nm excitation. Concentration-dependent luminescence properties were studied. The optimal Mn4+ doping concentration in Ca2GdTaO6 host was 0.004, and the concentration quenching mechanism was determined to be a dipole-dipole interaction among Mn4+ ions. Furthermore, the Ca2GdTaO6:0.004Mn4+ phosphor possessed the internal quantum efficiency up to 33% when excited at 355 nm. Besides, the decay lifetimes of Ca2GdTaO6:Mn4+ presented a reasonable downward trend with increasing Mn4+ concentration. In addition, the effect of charge compensation (co-doping of Li+, Na+, K+, and Mg2+ ions) on the luminescent properties of Ca2GdTaO6:Mn4+ phosphors was also investigated.
关键词： Indoor plant cultivation,Ca2GdTaO6,Mn4+,Double perovskite,Luminescence properties,Red phosphor
更新于2025-11-20 15:33:11
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A development of new red phosphor based on europium doped as well as substituted Barium Lanthanum Aluminate (BaLaAlO4: Eu3+)
摘要： New red emitting Eu3+ doped and substituted BaLaAlO4 phosphor powders were synthesized by simple modified solid state reaction method. BaLaAlO4 crystal phase formation studied through powder X-ray diffraction (XRD) analysis. Fourier Transform - Infra Red (FT-IR) analysis was performed to study the formation of the host with respect to temperature increment and metal-oxygen bond vibrations of BaLaAlO4 host lattice. Morphology of the phosphor was appeared as irregular in shapes with agglomeration. Photoluminescence (PL) analysis was performed to study the PL excitation and emission characteristics of the phosphor. It dictates that synthesized phosphors exhibited a strong red emission at 626 nm. Substitution effect of Eu3+ in BaLaAlO4 with various compositions such as Ba(1-x)LaAlO4: Eux3+, BaLa(1-y)AlO4: Euy3+ and BaLaAl(1-z)O4: Euz3+ were studied for PL enhancement. Luminescence decay time of the phosphors was also determined. PL thermal quenching and Commission Internationale de l'Eclairage (CIE) chromaticity analysis were carried out to find thermal stability and colour purity of the phosphor sample respectively. The Judd- Ofelt parameters (Ω2 & Ω4) obtained from the emission spectra of Eu3+ ions in BaLaAlO4 host lattice were evaluated and discussed.
关键词： BaLaAlO4,Eu3+,Red phosphor,Substitution effect,Solid state reaction
更新于2025-11-14 15:13:28
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Influences of sol-gel progress on luminescent properties of Li <sub/>1.0</sub> Nb <sub/>0.6</sub> Ti <sub/>0.5</sub> O <sub/>3</sub> :Eu <sup>3+</sup> red phosphor
摘要： Li1.0Nb0.6Ti0.5O3:3wt.%Eu3+ red phosphor was synthesized by sol-gel method. The influences of the pH value and the citric acid(CA)/ metal cations(M) ratio on the luminescent properties of the samples were discussed. The properties of the samples were characterized by X-ray diffraction(XRD) and photoluminescence spectroscopy, respectively. The results showed that the samples were consist of “M- phase”. Under the 466nm excitation, the orange emission at 592nm and the red emission at 612nm could be observed. The emission intensity increased with the increasing of pH value firstly and then decreased. The optimum pH value was 5.5. Moreover, the emission intensity decreased with the increasing of CA/M ratio. The relatively high emission intensity of the sample could be obtained when the CA/M was 3:1. Emission spectra and CIE coordinate of Li1.0Nb0.6Ti0.5O3:3wt.% Eu3+ were superior to commercial red phosphor Y2O3:Eu3+,which showed the red phosphor could have potential application in the White-LED field.
关键词： the red phosphor,Eu3+-doped,emission spectrum,Sol-gel method
更新于2025-09-23 15:23:52
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Double sites occupancy of Mn4+ in Cs2NaAlF6 with enhanced photoluminescence for white light-emitting diodes
摘要： In this work, we present a novel single-phase red phosphor of Cs2NaAlF6:Mn4t with two Al3t lattice sites, which shows two groups of vibrational phonon sidebands and ultra-intense zero phonon line (ZPL) under blue light illumination. The evidences have shown that the interesting spectral features originate from the non-equivalent occupation of Mn4t for both Al3t sites, which induces the neighboring cation vacancies surrounding Mn4t and highly distorted [MnF6] octahedral in the Cs2NaAlF6 host. The luminescent behavior of double sites occupied by Mn4t can absorb researchers’ interest on novel red-emitting phosphors. Pro?ting from the photoluminescence (PL) features, superior color rendering index of Ra ? 90.3, R9 ? 81, and low correlated color temperature of Tc ? 3967 K are achieved from white light-emitting diode (LED) by using yellow Y3Al5O12:Ce3t (YAG) and red Cs2NaAlF6:Mn4t phosphors as blue light converters. These results suggest that Cs2NaAlF6:Mn4t phosphor has a stupendous potential for LED lighting.
关键词： Red phosphor,Cs2NaAlF6:Mn4t,Luminescence properties,LED,Double sites occupancy
更新于2025-09-23 15:21:01
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High performance red/deep-red emitting phosphors for white LEDs
摘要： Highly efficient oxide based red line emitters are still bottleneck for the smart white LEDs. In the present investigation, sequences of narrow band red emitting phosphors were synthesized through the conventional solid-state technique. The X-ray diffraction studies reveals that the synthesized phosphors were crystallized in the trigonal phase with space group I41/a (88). Under 395 nm excitation, NaSrGd(MoO4)3:Eu3+ phosphors shown sharp red emission around at 616 nm because of the 5D0→7F2 transition (ED transition). Moreover, the internal quantum efficiency (IQE) was found to be 82 %, and the thermal stability study showed that the NaSrGd0.5Eu0.5(MoO4)3 phosphor retains the emission intensity around 71.5% at 423K of its initial room temperature. The red LEDs were designed for the NaSrGd0.5Eu0.5(MoO4)3 red phosphors with the NUV LED chip. White LED also been fabricated by conjugating the blue LED with yellow dye + red phosphor and the LED shown CCT (6823 K), CRI (74%), CIE (0.306, 0.331). The Sm3+ and Eu3+ co-doped deep red phosphor were synthesized and studied for the plant growth. The LED emission of Sm3+ and Eu3+ co-doped phosphor is completely covers the absorption spectrum of Phytochrome Pr. All of these consequences revealed that the synthesized phosphor could be the efficient red emitting phosphor for warm white LEDs and plant growth filed research.
关键词： Eu3+ red phosphor,Quantum Yield,White LED,Plant growth,Molybdate
更新于2025-09-23 15:19:57
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Strong Narrow Red Emission in a Perturbed Fergusonite System: Y3Mg2Nb3O14:Eu3+ for White LED Applications
摘要： A series of intense red-emission phosphors, Y3Mg2Nb3O14:Eu3+, with higher color purity were prepared via the conventional high-temperature ceramic route. The influence of Mg2+ ion incorporation in the highly symmetrical YNbO4 lattice on the luminescence properties was studied using powder x-ray diffraction, scanning electron microscopy with energy dispersive spectrometry, UV–visible absorption spectroscopy, and photoluminescence measurements. The developed phosphors crystallize into a monoclinic fergusonite-type structure with a C2/c space group even with the addition of Mg into the system. These phosphors display intense, sharp, red emission with a maximum at 613 nm under near-UV excitation. The photoluminescence studies suggest that Mg addition perturbs the A site network forming cation pairs of Eu3+-Y3+, Eu3+-Mg2+, and Eu3+-Eu3+ connected with O2? ions. The preferential occupation of cations in the A site network by the incorporation of Mg2+ ions in the YNbO4 host lattice induces Eu3+-Eu3+ separation and results in intense, sharp, red emission due to increased radiative probabilities. Moreover, the color purity of the Y3?xMg2Nb3O14:xEu3+ phosphor could achieve 92.4% that is attributed to the narrow full width at half maximum (FWHM ≈ 4 nm) of the red emission peaking at 613 nm. More importantly, the luminescence intensity of the developed phosphor is 9.4 times greater than that of the Philip’s red phosphor under near-UV excitation. Because of the intriguing red luminescence, phosphors exhibit Commission Internationale de l’Elcairage color coordinates (0.63, 0.35) close to the National Television System Committee standards, low correlated color temperature values for warm white lighting, and greater color purity (92.4%) for improving the color rendering index, which makes them a potential candidate for use in the fabrication of white light-emitting diodes.
关键词： perturbation,luminescence,fergusonite,Red phosphor
更新于2025-09-23 15:19:57
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A novel Mn4+ doped red phosphor composed of MgAl2O4 and CaAl12O19 phases for Light-Emitting Diodes
摘要： The red emitters based on CaAl12O19:Mn4+ have been attracting extensive attentions due to their advantages of rare-earth-free and chemical stability. However, their relatively low luminescent efficiencies will seriously hinder their application for light-emitting diodes (LEDs). In this regard, one of promising red phosphors of CaAl12O19:Mn4+ was synthesized with enhanced luminous efficiency by introducing the coexistence phase of MgAl2O4. Importantly, an approximately 5 times enhancement of integrated intensity on emission spectrum was observed in the coexistence phase comparing of these single one. Their crystalline structures, morphologies, photoluminescence as well as the mechanism of improved luminescence were systematically investigated. Exciting them by using near-ultraviolet or blue LEDs, an efficient red emission was achieved with a maximum peak at ~ 658 nm. In order to evaluate the potential application, a warm white LED and a plant-growth LED are fabricated by using the prepared phosphors in combination with YAG:Ce3+ and InGaN-based blue chips.
关键词： MgAl2O4,LEDs,CaAl12O19,red phosphor,Mn4+
更新于2025-09-23 15:19:57
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Optical spectroscopy of thermal stable Na2ZnP2O7: Sm3+/ (Li+, K+) phosphors
摘要： Na2ZnP2O7 pyrophosphates doped with different concentrations of Sm3+ were synthesized successfully via a solid-state reaction process. A vibrational Raman-IR spectroscopic and diffraction analysis has been performed. The Na2ZnP2O7: Sm3+ powders were crystallized in a tetragonal lattice with P42/mnm space group. The photoluminescence (PL) emission and PL excitation (PLE) spectra were studied as a function of Sm3+ concentration. The optimal Sm3+ doping concentration in Na2ZnP2O7 host matrix is determined to be 1 mol%. In order to enhance the luminescent intensity of these phosphors, the compensator charge Li+ and K+ ions were introduced in the Na2ZnP2O7 host. Furthermore, the luminescence of Na2ZnP2O7: Sm3+ indicates good thermal stability at high temperatures. The chromaticity diagram of the Commission International de l'Eclairage (CIE) was investigated, indicating a bright orange-red emission. Hence, the obtained results indicate that the as-prepared phosphor can be a potential candidate for application in Light Emitting Diodes (LEDs).
关键词： thermal stability.,Orange-red phosphor,Na2ZnP2O7,Luminescent material
更新于2025-09-19 17:15:36
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Temperature-Dependent Luminescence of Red-Emitting Ba2Y5B5O17: Eu3+ Phosphors with Efficiencies Close to Unity for Near-UV LEDs
摘要： Solid state white light sources based on a near-UV LED chip are gaining more and more attention. This is due to the increasing e?ciency of near-UV-emitting LED chips and wider phosphors selection if compared to devices based on blue LED chips. Here, a brief overview is given of the concepts of generating white light employing near-UV LED and some optical properties of the available phosphors are discussed. Finally, the synthesis and optical properties of very e?cient red-emitting Ba2Y5B5O17:Eu3+ phosphor powder and ceramics is reported and discussed in terms of possible application as a red component in near-UV LED-based white light sources.
关键词： Eu3+,ceramics,near-UV LED,quantum e?ciency,luminous e?cacy,red phosphor,borate,CIE 1931 colour coordinates,thermal quenching
更新于2025-09-19 17:13:59