MOLECULES
·
2024
·Vol. 29
·期 6
·1402
·
IF 4.2
Zaifa Yang,Ruoxuan Wang,Shuyu Yang,Hongxia Bu,Jingfen Zhao
Mn4+-doped red-light-emitting phosphors have become a research hotspot that can effectively enhance photosynthesis and promote morphogenesis in plants. Herein, the red phosphor La3Mg2NbO9:Mn4+was synthesized through the solid-state reaction method. The effects of adding H3BO3and a charge compensator R+(R = Li, Na, K) on the crystal structure, morphology, quantum efficiency, and luminous performance of the La3Mg2NbO9:Mn4+phosphor were systematically analyzed, respectively. The results showed that adding H3BO3flux and a charge compensator improved the quantum efficiency and luminescence intensity. The emission intensity of the phosphor was enhanced about 5.9 times when Li+was used as the charge compensator, while it was enhanced about 240% with the addition of H3BO3flux. Remarkably, it was also found that the addition of H3BO3flux and a charge compensator simultaneously improved the thermal stability at 423 K from 47.3% to 68.9%. The prototype red LED fabricated using the La3Mg2NbO9:Mn4+,H3BO3,Li+phosphor exhibited a perfect overlap with the phytochrome absorption band for plant growth. All of these results indicate that the La3Mg2NbO9:Mn4+,H3BO3,Li+phosphor has great potential for use in agricultural plant lighting.
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高影响因子
Solids
·
2025
·Vol. 6
·期 3
·53
·
IF 2.4
Chenxing Liao,Huihuang Cai,Dongyuan Dai,Liaolin Zhang
Mg2TiO4:Mn4+(MTO:Mn4+) red phosphor has important applications in areas such as red LEDs and forensic science, but the preparation of MTO:Mn4+through the solid-state reaction method requires a high sintering temperature. Herein, MTO:Mn4+red phosphor was synthesized using the solid-state reaction method with LiCl flux, and its crystallographic structure and photoluminescence properties were studied to determine the influence of experimental parameters like the amount of fluxing agent added and sintering temperature in producing a bright red phosphor suitable for LEDs. The experimental results showed that samples with added LiCl could form pure MTO after sintering at 950 °C, whereas those without LiCl still contained a mixture of MTO and MgTiO3, even when sintered at 1400 °C. The optimal performance was achieved with a sample doped with 0.2 mol% Mn4+, synthesized using 50 wt% LiCl flux and sintered at 950 °C for 12 h. This sample exhibited a broad excitation band and a narrow red emission band peaking at 662 nm, confirming its excellent luminescence properties. Furthermore, a prototype red LED fabricated with a 377 nm chip and MTO:0.2% Mn4+phosphor achieved photoelectric conversion efficiency of 78.5% at a 100 mA drive current, confirming its viability for high-performance red LED manufacturing.
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DALTON TRANSACTIONS
·
2017
·Vol. 46
·期 40
·13835-13844
·
IF 4.029
Luqing Xi,Yuexiao Pan,Mengmeng Zhu,Hongzhou Lian,Jun Lin
A novel red phosphor, NaHF2:Mn4+ (NHF:Mn), was obtained via substituting Na+ located at the center of the octahedron coordinated with six F− ions with Mn4+ in the host lattice of NHF. The phase purity and the exact composition of the obtained NHF:Mn were confirmed by X-ray powder diffraction (XRD), Rietveld refinement, energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and infrared (IR) spectroscopy, respectively. The luminescence intensity of NHF:Mn was enhanced by optimizing the synthetic conditions. A series of warm white light-emitting diodes (WLEDs) with a color rendering index (CRI) higher than 88.0 and correlated color temperatures (CCT) between 3146 and 5172 K were obtained by encapsulating the as-prepared red phosphor NHF:Mn with the yellow one Y3Al5O12:Ce3+ (YAG:Ce) on blue chips. The advantage of the synthetic strategy to obtain NHF:Mn can be extended to develop novel Mn4+ doped red phosphors via substituting for central ions with unequal electric charge in the centers of octahedra.
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高影响因子
Inorganic Chemistry Frontiers
·
2025
·
IF 6.4
Ziang Peng,Yuanjing Wang,Chuang Zhang,Hong Ming,Zhen Chen,Renhua Guo,Enhai Song,Qinyuan Zhang
Mn4+ non-equivalent doped fluorides with long-wavelength and narrow-spectrum emission ensure ultrawide-gamut display applications. However, the existing synthesis schemes result in the suboptimal quantum efficiency of non-equivalent doped materials. This study develops a group-substituted single crystal (GSC) method assisted by pre-nucleation strategy to achieve the growth of high-quality K2LiGaF6:Mn4+ single crystals with optimal photoluminescence performance and chemical stability. To avoid the adverse effects caused by the long reaction time of Mn4+, the GSC method achieves rapid preparation of K2LiGaF6:Mn4+ single crystals within 12 hours, which is 90% shorter than typical methods and beneficial in preventing the degradation of Mn4+. As a result, it not only achieves a high external quantum efficiency of 57.15% but also exhibits excellent stability. A white light-emitting diode (LED) fabricates using blue light chip, commercial green phosphor (β-Sialon:Eu2+) and the optimized KLGFM-GSC crystal can achieve an ultrawide color gamut display of 109.3% National Television Standards Committee (NTSC). In summary, the method of synthesizing single crystals with GSC has good universality, opening a new way for the preparation of high-quality Mn4+ non-equivalent doped fluoride single crystals and promoting the development of ultrawide color gamut display applications.
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Journal of Materials Chemistry C
·
2018
·Vol. 6
·期 48
·13136-13147
·
IF 5.976
Gongcheng Xing,Yuxin Feng,Min Pan,Yi Wei,Guogang Li,Peipei Dang,Sisi Liang,Maxim S. Molokeev,Ziyong Cheng,Jun Lin
Red-emitting phosphors are indispensable compounds which are used to achieve a warm white light in phosphor-converted white light emitting diodes (pc-WLEDs). However, the luminous efficiency and stability of red phosphors are still big challenges. In this work, we developed red-emitting double perovskite phosphors La2ATiO6:Bi3+,Mn4+ (A = Mg, Zn) (LAT:Bi3+,Mn4+) and discuss the relationship between the double perovskite phosphor structure and the luminescence performance in detail. According to the Rietveld refinement results for the La2Mg(1−w)ZnwTiO6:Bi3+,Mn4+ (0 ≤ w ≤ 1) (LM(1−w)ZwT:Bi3+,Mn4+) solid solution, the proposed mechanism of the spectral adjustment is ascribed to the appearance of the phase transition, which results in a lower local structural symmetry of the [LaO12] polyhedron and the variation of the crystal field environment for Mn4+. Notably, this is the first time that the influence of the local structure variation on the luminescence tuning in double perovskite structure phosphors has been revealed, and this could offer guidance for the development of new phosphor system. By designing Mg2+/Zn2+ cation substitution, the internal quantum efficiency (IQE) is remarkably enhanced beyond 20%. In addition, we succeeded in achieving a Bi3+/Mn4+ co-doped energy transfer in the double perovskite structure phosphors. Owing to the Bi3+ → Mn4+ energy transfer in LAT, the red emission of the Mn4+ ions could be dramatically enhanced. The energy transfer efficiency of LAT:Bi3+,Mn4+ eventually exceeded 90%. The IQE and the thermal stability were all enhanced by around 30% compared to the non-co-doped samples, respectively. These results indicate that the Bi3+ → Mn4+ energy transfer strategy could play a pivotal role in the development of highly efficient red-emitting phosphors. The performance of the fabricated pc-WLEDs devices indicates that LAT:Bi3+,Mn4+ could be a promising red phosphor for near ultraviolet (n-UV) based warm pc-WLEDs.
研究领域:
材料科学
·
光学材料
·
固态化学
·
光子学
·
发光材料
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ELECTROCHIMICA ACTA
·
2026
·
IF 5.8
Yunqin Yang,Minyi Liao,Fanjun Tang,Xuanchen Wei,Donglou Ren,Tianquan Liang
P2-type Na 0.65 Mn 0.75 Ni 0.25 O 2 (NMNO) has been widely investigated as a promising cathode material for sodium-ion batteries (SIBs) owing to its high specific capacity and excellent structural stability. However, deterioration of cycling stability and Na + diffusion kinetics occurs in the P2-NMNO cathode due to the irreversible P2–to–O2 phase transformation, reinforced Na + /vacancy ordering, Jahn–Teller effect and so on during electrochemical processes, especially at high voltages. In the quest to improve P2 cathodes for SIBs, the Na 0.65 Mn 0.75 Ni 0.25-x Li x O 2 ( x = 0, 0.05, 0.1, 0.2) with Li substitution for Ni was studied. This deliberate substitution is found to regulate Na + site occupancy, disrupt cation ordering to enable faster ion diffusion, and effectively optimize the Mn 3+ /Mn 4+ redox couple, thereby suppressing the detrimental phase transition. As a synergistic result of these effects, the Li + -doped NMNO-Li0.1 cathode exhibits good electrochemical performance: it delivers 92.1 % capacity retention after 200 cycles at an ultrahigh rate of 20 C and achieves an increased Na + diffusion coefficient compared to the pristine material.
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DALTON TRANSACTIONS
·
2023
·Vol. 52
·期 17
·5587-5596
·
IF 4
Zhijian Liao,Yan Li,Jiaxing Zuo,Guang Chen,Heng Liang,Shihao Wu,Jiaqing Peng,Xinyu Ye
For high-efficiency lighting and wide color gamut backlight display, high-quality narrow-band red phosphors for WLEDs are still in high demand. Herein, a novel red-emitting fluoride phosphor Cs2NaGaF6:Mn4+ was successfully synthesized by a simple two-step co-precipitation method and exhibits ultra-intense zero-phonon lines (ZPLs) and long wavelength phonon sidebands under 468 nm blue light irradiation. The ZPL emission peak of Cs2NaGaF6:Mn4+ was located at 627 nm, which is much stronger than its υ6 vibration peak, more matchable with the eye-sensitive region of humans, and beneficial for obtaining higher luminous efficiency of WLEDs. Interestingly, the υ6 vibration peak of this red phosphor is at 636.5 nm, which is larger than that of the common fluoride phosphor A2BF6:Mn4+ (usually at about 630 nm, represented by K2SiF6:Mn4+) at about 6.5 nm. Thanks to the longer wavelength of the υ6 vibration peak, the chromaticity coordinates (0.7026, 0.2910) with a larger x-coordinate value were realized, leading to a potentially wider color gamut of WLEDs. In addition, this phosphor has high thermal stability and its emission intensity at 423 K remains 93.7% of the initial intensity at room temperature. The lumen efficiency of WLED1 packaged with a mixture of Cs2NaGaF6:Mn4+ and YAG:Ce3+ on the InGaN blue chip is 115.7 lm W−1 with the color temperature (Tc) = 3390 K and the colour rendering index (Ra) = 92.5 under 20 mA driving current. The chromaticity coordinates of WLED2 packaged with Cs2NaGaF6:Mn4+ and β-SiAlON:Eu2+ on the InGaN blue chip are (0.3149, 0.3262) and the calculated color gamut is up to 118.4% (NTSC). These results indicate that Cs2NaGaF6:Mn4+ red phosphors have promising applications in the high-quality lighting and display fields.
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INORGANIC CHEMISTRY
·
2018
·
IF 4.7
Chunyan Jiang,Mingying Peng,Alok M. Srivastava,Lihua Li,Mikhail G. Brik
Narrow band red-emitting Mn4+-doped fluoride phosphor is an essential red component of modern white-light-emitting-diode (WLED) devices. Its luminescence has sensitivity to structure and influences the performance of WLED. In this paper, we report a high-performance Mn4+ phosphor based on a new heterodialkaline fluorogermanate, CsNaGeF6:Mn4+. As determined by the single-crystal X-ray diffraction analysis, the CsNaGeF6 compound crystallizes in the orthorhombic crystal system with space group Pbcm (No. 57). Under excitation by 360 and 470 nm photons, CsNaGeF6:Mn4+ emits intense red light near 630 nm with a high quantum yield of 95.6%. The electronic energy levels of the Mn4+ ion in Cs2GeF6, Na2GeF6, and CsNaGeF6 are calculated using the exchange charge model of crystal-field theory. The local Mn4+ environment inducing different zero-phonon-line emissions in the structures is probed by electron paramagnetic resonance. The Mn4+-doped heterodialkaline fluorogermanate CsNaGeF6:Mn4+ exhibits broader emission as a result of the lowest symmetry. It has higher quantum yield than Na2GeF6:Mn4+ and higher spectral luminous efficacy than Cs2GeF6:Mn4+. Given the good thermal stability and efficient luminescence, a prototype warm-WLED device with a color rendering index of 92.5, a correlated color temperature of 3783 K, and a luminous efficacy of 176.3 lm/W has been fabricated by employing the CsNaGeF6:Mn4+ phosphor as the red component. Our results not only reveal that a high-performance Mn4+ red phosphor is achieved through cationic substitutions but also construct a relationship of performance–structure to guide the design of Mn4+ phosphors in the future.
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Advanced Optical Materials
·
2019
·Vol. 7
·期 12
·1900093
·
IF 7.125
Sisi Liang,Guogang Li,Peipei Dang,Yi Wei,Hongzhou Lian,Jun Lin
Currently, Mn 4+ -activated red-emitting materials are the research hotspot due to their promising application in phosphor-converted white light-emitting diodes (w-LEDs). Here, a typical cation substitution strategy is reported to optimize Mn 4+ -doped germinate phosphor for improving luminescence performances. The effect of cation substitution for Ge 4+ ions by Ti 4+ , Sn 4+ , and Si 4+ ions on lattice structure, photoluminescence properties, and thermal stability of the as-prepared Mn 4+ -doped germinates is systematically investigated. A significant improvement of emission intensity with Ti 4+ doping should benefit from the resonance emission enhancement effect. Some lattice distortion defects contribute to the thermal stability enhancement, which plays a role in driving the excited phonon traps to compensate the energy loss of nonradiative transition. Surprisingly, abnormal variation in intensity of anti-Stokes and Stokes emission peaks with changing temperature is first observed, revealing a potential application in thermometry. The electroluminescence performances of as-fabricated w-LED devices using Mg 14 Ge 5 Ti 0.5 O 24 :Mn 4+ red phosphor are evaluated, which possess higher color rendering index ( R a = 87.3) and luminous efficiency (109.42 lm W −1 ) as well as lower color correlated temperature (3566 K) than those using Cs 2 GeF 6 :Mn 4+ and CaAlSiN 3 :Eu 2+ red phosphors. The results reflect the superiority of the studied phosphor in w-LEDs and optical thermometry areas.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2018
·
IF 3.779
Jiasong Zhong,Xiao Chen,Daqin Chen,Meijiao Liu,Yiwen Zhu,Xinyue Li,Zhenguo Ji
Developing a novel non-rare-earth activated oxide red phosphor with admirable luminescent performance and low cost is still of great interest in the field of energy-saving warm white light-emitting diodes (w-LEDs) illumination. Here, Li 3 Mg 2 SbO 6 :Mn 4+ (LMSO:Mn 4+ ) red-emitting phosphor has been successfully prepared with cheap raw materials via a traditional solid-state method. Crystal structure, morphology, composition as well as optical properties are studied in detail. The prepared LMSO:Mn 4+ phosphor exhibits a broad and deep red emission band in the range of 600–750 nm with the maximum centered at 666 nm, which is ascribed to the Mn 4+ : 2 E g → 4 A 2g transition in [SbO 6 ] octahedral environment. Moreover, the nephelauxetic effect of Mn 4+ in the LMSO matrix is evaluated by investigating the crystal field strength (Dq) and Racah parameters (B and C). Importantly, LMSO:0.01Mn 4+ phosphor demonstrates good thermal stability and high quantum efficiency. By embedding LMSO:Mn 4+ and Y 3 Al 5 O 12 :Ce 3+ phosphors with various ratios in the TeO 2 -based glass host, a series of phosphors-in-glass(PiG) composites are achieved and demonstrate to remain the original optical properties of phosphors. Remarkably, by coupling PiG color converters with a blue LED chip, high-power w-LEDs devices with tunable optoelectronic parameters are constructed, with the correlated color temperature evolving from cool white (6783 K) to warm one (4014 K) and the color rendering index increasing from 72.2 to 88.7.
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RSC Advances
·
2016
·Vol. 6
·期 80
·76251-76258
·
IF 3.289
Luqing Xi,Yuexiao Pan,Shaoming Huang,Guokui Liu
The synthesis procedures of red phosphors activated by Mn4+ that are carried out especially at room temperature, are significant to industrialization. Herein, we report a facile strategy to obtain two red micro-crystal phosphors: (NH4)2TiF6:Mn4+ (NTF:Mn) and (NH4)2SiF6:Mn4+ (NSF:Mn) through ion exchange at room temperature for a few hours. Raw materials NTF and NSF act as host lattices of red micro-crystal phosphors, and activator Mn4+ ions are from K2MnF6/HF and/or mixed KMnO4/HF solution. The reaction mechanism for the synthesis process has been comprehensively discussed in detail. The typical red emitting luminescence of Mn4+ with strong absorption in the blue region and the large size of about 200 μm of red micro-crystal phosphors NTF:Mn make it an attractive candidate material as a red compensator for resin-free white light-emitting diodes with high color rendering index. The dependence of emission intensity on concentration of HF and KMnO4, and measurement temperature has been investigated. The advantage of the proposed strategy is the ability to explore Mn4+ doped red phosphors from low-cost starting materials at room temperature for large scale industrial applications.
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高影响因子
Materials Today Communications
·
2024
·
IF 3.7
Feng Hong,Long Li,Maoyu Xu,Haiqing Su,Yunkai Dong,Jingjing Zhang,Dechuan Yu,Hai Lin
Mn 4+ -doped fluoride phosphors have important application value in the background light and WLED lighting fields. Therefore, the synthesis of efficient and stable Mn 4+ -doped red phosphor is of great application value. In this study, a series of red-emitting K 2 NaAl 1- y Ga y F 6 : x Mn 4+ ( y = 0, 0.2, 0.4, 0.6, 0.8 and 1) ( x = 0.01, 0.03, 0.05, 0.07 and 0.09) solid solution phosphors are successfully synthesized by simple coprecipitation method. The synthesis strategy of simple crystal structure optimization is proposed to realize simultaneously the crystal field optimization, luminescence enhancement and thermal stability of red phosphor. The calculation and theoretical analysis of crystal field strength are used to prove that solid solution matrix K 2 NaAl 0.4 Ga 0.6 F 6 is the most ideal matrix material. X-ray powder diffraction, energy-dispersive X-ray spectrometer and scanning electron microscope are employed to determine the crystal structure, composition and morphology of all samples. Optical properties are characterized using excitation spectra, emission spectra and fluorescence lifetime curves. Moreover, the CIE coordinates of red-light show that the phosphor has low correlated color temperature and excellent color purity. Intriguingly, the as-prepared K 2 NaAl 0.4 Ga 0.6 F 6 :Mn 4+ phosphor possesses admirable thermal quenching behavior and color stability at high temperature. At a temperature of 423 K, the photoluminescence intensity can be maintained at 52 % of the original intensity (298 K). The activation energy, the chromaticity shift and chromaticity coordinate variation are also systematically calculated. More importantly, A high-performance warm WLED with low correlated color temperature (CCT = 3982 K) and high color rendering index (R a = 93.7) is achieved by using K 2 NaAl 0.4 Ga 0.6 F 6 :Mn 4+ as a red-emitting material. These results demonstrate that K 2 NaAl 0.4 Ga 0.6 F 6 :Mn 4+ red phosphor provides a novel choice for the warm WLED required for indoor lighting.
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