CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Yajun Jia,Chengdong Peng,Meng Gao,Keqin Yang,Aiying Wang,Yuexiao Pan
Owing to the ease of synthesis and the unique luminescence characteristics for the applications of white light emitting diodes (WLEDs), the red-emitting fluoride phosphors activated by Mn 4+ ions are critical to achieving WLEDs with ideal color rendering index (CRI). In this work, a new type of Mn 4+ doped phosphor KRb 3 Ge 2 F 12 :Mn 4+ (KRGF:Mn) has been synthesized by a simple ion-exchange method in atmosphere. A strategy of surface modification by using a weak reducing agent oxalic acid (OA) is proposed, which can essentially improve the moisture stability of phosphor KRGF:Mn. Moreover, the modified phosphors can still maintain bright red light after being completely immersed in water for more than 100 days. A group of LEDs combined with the as-synthesized phosphor KRGF:Mn as a light source can be well applied to artificial lighting for the growth of tomatoes and Chinese cabbage plants. Additionally, the luminescence efficiency of KRGF:Mn has been optimized with high thermal stability. This work will provide high-quality red phosphor for LED lighting sources that being required for indoor plant growth.
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高影响因子
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
·
2021
·
IF 4.291
Wei Li,Liangling Sun,Balaji Devakumar,Nan Ma,Zongjie Zhang,Xiaoyong Huang
In this work, we demonstrated novel Mn 4+ -activated double-perovskite SrLaZnSbO 6 (SLZS) far-red-emitting phosphors for plant cultivation LED lighting. These SLZS:Mn 4+ far-red-emitting phosphors doped with various Mn 4+ concentrations were successfully prepared by using a traditional high-temperature solid-state reaction route. The phase purity, crystal structure, photoluminescence properties, decay lifetimes, CIE chromaticity coordinates and temperature-dependent spectra of as-prepared samples were systematically studied. The SLZS:Mn 4+ phosphors showed an intense far-red emission band in the 650−800 nm spectral region with a maximum at 706 nm under 364 nm excitation, which was due to the 2 E g → 4 A 2g transition of Mn 4+ ions. The optimal doping concentration of Mn 4+ ions in SLZS:Mn 4+ phosphors was found to be 0.5 mol%. And the CIE chromaticity coordinates of SLZS:0.5 %Mn 4+ phosphors were calculated to be (0.7276, 0.2724), which were located in the far-red region. The emission spectrum of SLZS:Mn 4+ phosphors could match well with the absorption band of phytochrome P FR . All of these results demonstrate that SLZS:Mn 4+ phosphors have a huge potential application in indoor plant cultivation.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Lei Chen,Peng Cheng,Guifang Zheng,Gang Yao,Pingjuan Zhang,Haiwu Zheng,Lei Ding,Xuemei Ding,Shizhong Wei,Haiyong Ni
K 2 TiF 6 :Mn 4+ , along with K 2 SiF 6 :Mn 4+ and K 2 GeF 6 :Mn 4+ , is a red phosphor with narrow-band emission for wide-gamut display backlight LEDs. However, its poor absorbance results in low external quantum efficiency, which is a major obstacle for commercial utilization. This paper describes our pursuit of a new path to synthesize the K 2 TiF 6 :Mn 4+ phosphor through cation-exchange-assisted recrystallization achieving excellent performance. The absorbance and the internal and external quantum efficiencies of the as-prepared phosphor reached up to 74.27, 93.06, and 69.09%, respectively; the luminescence intensity at 150 °C was 97.5% of that at 25 °C. The color gamut of white LEDs packaged with optimized K 2 TiF 6 :Mn 4+ covers 98.61% of the NTSC (National Television Standard Committee) color gamut and the amount of phosphor used was reduced by 37.55%, as compared with commercially available LEDs achieving similar performance. These breakthroughs strongly support the commercial implementation of K 2 TiF 6 :Mn 4+ phosphors.
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高影响因子
Chemistry-An Asian Journal
·
2020
·Vol. 15
·期 20
·3326-3337
·
IF 4.056
Lili Liu,Di Wu,Shengan He,Zejian Ouyang,Junfei Zhang,Fu Du,Jiaqing Peng,Fengli Yang,Xinyu Ye
Graphical A reverse strategy was successfully developed to restore the almost completely degraded luminescence properties of Mn 4+ -doped fluoride phosphors and simultaneously improve the resistance to moisture. Fluoride phosphors as red components for warm white LEDs have attracted a tremendous amount of research attention. But these phosphors are extremely sensitive to moisture, which seriously limits their practical industrial applications. To tackle this problem, unlike all the straightforward preventive strategies, a reverse strategy “Good comes from bad” was successfully developed to treat the degraded K 2 SiF 6 : Mn 4+ (D-KSFM) phosphor in the present study, which not only completely restores the luminescence properties, but also significantly enhances the moisture resistance at the same time. After treatment with an oxalic acid solution as restoration modifier, the emission intensity of the D-KSFM phosphor can be restored to 103.7% of the original K 2 SiF 6 : Mn 4+ red phosphor (O-KSFM), and the moisture resistance is remarkably improved. The restored K 2 SiF 6 : Mn 4+ (R-KSFM) maintains approximately 62.3% of its initial relative emission intensity after immersing in deionized water for 300 min, while the reference commercial K 2 SiF 6 : Mn 4+ with a protective coating (C-KSFM) is only 33.2%. As a proof of general applicability, this strategy was also conducted to K 2 TiF 6 : Mn 4+ phosphor, which is less moisture-stable than K 2 SiF 6 : Mn 4+ . The luminescence intensity of the degraded K 2 TiF 6 : Mn 4+ (D-KTFM) phosphor can be restored to 162.6% of original level of the K 2 TiF 6 : Mn 4+ synthesized through a cation exchange approach without any treatment (O-KTFM). The emission intensity of the restored K 2 TiF 6 : Mn 4+ (R-KTFM) phosphor retains 62.8% of its initial emission intensity after soaking in deionized water for 300 min. Finally, the R-KSFM phosphors were packaged into white light-emitting diodes with blue InGaN chips and Y 3 Al 5 O 12 : Ce 3+ yellow phosphors. The WLEDs display excellent color rendition with higher color rendering index, lower color temperature (WLED-II: R a =83.6, R 9 =57.3, 3743 K, η l =199.68 lm/W; WLED-III: R a =90.4, R 9 =94.2, 2892 K, η l =183.3 1 m/W). The above results show that the reverse strategy can be applied in those phosphor materials with poor moisture resistance to restore luminescence properties and improve moisture resistance without excessively care about the deterioration during the production, storage and transportation.
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PubMed
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Shuai Zou,Gang Wang,Yiming Zhang,Caihong Xue,Huiyuan Chen,Guijun Yang,Hui Nan,Haomin Wei,Hong Lin
Lithium titanate (Li 4 Ti 5 O 12 , LTO) has several disadvantages as active material for Li-ion batteries (LIBs) such as low conductivity and poor capacity. To overcome these drawbacks and specifically to improve electrical performance of LTO, we used solvothermal method to synthesis LTO and to dope it simultaneously with Al and Mn. Doped LTO was then incorporated into composites containing graphene (G), carbon nanotube (CNT) or carbon quantum dots (CQDs) to enhance specific capacity and conductivity of LIB anodes containing these composites as active materials. To have a further study of different carbon materials composite with doped LTO, these materials we obtained were thoroughly characterized. LTO doping and incorporation into composites not only increased its specific capacity and also decreased its impedance. Al 3+ and Mn 4+ substituted Ti 4+ located at 16 d sites. First cycle specific capacity values and impedance values of anodes consisting of composites containing doped LTO and G, CNT or CQDs were 261.7, 286.2 and 296.5 mA h/g (at C/10 rate) and 13.99, 8.28, 18.79 Ω, respectively. Capacity retention after 100 cycles for these anodes was 84.6, 90.67 and 83.4%. LTO doping by Al 3+ and Mn 4+ and combining it with G, CNT or CQDs effectively improved its electrochemical performance. The best performance was obtained for anodes containing composites consisting of a combination of doped LTO and CNT.
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高影响因子
ACS Applied Materials & Interfaces
·
2017
·
IF 7.504
Enhai Song,Jianqing Wang,Jiahao Shi,Tingting Deng,Shi Ye,Mingying Peng,Jing Wang,Lothar Wondraczek,Qinyuan Zhang
Following pioneering work, solution-processable Mn4+-activated fluoride pigments, such as A2BF6 (A = Na, K, Rb, Cs; A2 = Ba, Zn; B = Si, Ge, Ti, Zr, Sn), have attracted considerable attention as highly promising red phosphors for warm white light-emitting diodes (W-LEDs). To date, these fluoride pigments have been synthesized via traditional chemical routes with HF solution. However, in addition to the possible dangers of hypertoxic HF, the uncontrolled precipitation of fluorides and the extensive processing steps produce large morphological variations, resulting in a wide variation in the LED performance of the resulting devices, which hampers their prospects for practical applications. Here, we demonstrate a prototype W-LED with K3AlF6:Mn4+ as the red light component via an efficient and water-processable cation-exchange green route. The prototype already shows an efficient luminous efficacy (LE) beyond 190 lm/W, along with an excellent color rendering index (Ra = 84) and a lower correlated color temperature (CCT = 3665 K). We find that the Mn4+ ions at the distorted octahedral sites in K3AlF6:Mn4+ can produce a high photoluminescence thermal and color stability, and higher quantum efficiency (QE) (internal QE (IQE) of 88% and external QE (EQE) of 50.6%.) that are in turn responsible for the realization of a high LE by the warm W-LEDs. Our findings indicate that the water-processed K3AlF6 may be a highly suitable candidate for fabricating high-performance warm W-LEDs.
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PubMed
高影响因子
MOLECULES
·
2024
·Vol. 29
·期 6
·1402
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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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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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高影响因子
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
Journal of Materials Chemistry C
·
2017
·Vol. 5
·期 47
·12422-12429
·
IF 5.256
T. T. Deng,E. H. Song,Y. Y. Zhou,L. Y. Wang,Q. Y. Zhang
Three isotypic double perovskites A2BAlF6:Mn4+ (A = Rb, Cs; B = K, Rb) were synthesized via a facile co-precipitation method at room temperature. XRD Rietveld refinements and Raman spectra indicate that the neighboring smaller A-site or larger B-site cation in A2BAlF6:Mn4+ lowers structural stability, but suppresses the [AlF6] octahedron to increase the crystal field strength and bond strength of the Al–F bond. Cs2KAlF6:Mn4+ presents a sharp line red light and excellent moisture resistance, but experiences severe thermal quenching. In comparison, altering the A- or B-site cation to Rb, Rb2KAlF6:Mn4+ and Cs2RbAlF6:Mn4+ shows blue shifts in emission and declining water resistance, but enhancements in thermal stability. A combination of static and dynamic emission degradations demonstrates that the water resistance of Mn4+ emission mainly relies on the structural stability of the host matrix; meanwhile, the thermal stability highly depends on the rigidity of its local accommodation. The variations of the temperature-dependent white light-emitting diode (WLED) performances further evidence their sufficient thermal stability for LED applications. These findings suggest that neighboring-cation modulation might be a feasible guideline for exploiting stable Mn4+-activated fluoride red phosphors in warm WLED applications.
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高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Kaiyuan Deng,Yahong Jin,Lifang Yuan,Haoyi Wu,Yihua Hu
Phosphor-converted light-emitting diode (pc-LED) technology, as artificial lighting source, is the most promising option for providing power for plant growth in future smart agricultural factories. However, developing red phosphors with the desired emission spectral range and good thermal stability is still experimental. In this study, an Mn 4+ -doped BaZrGe 3 O 9 red-emitting phosphor with remarkable thermal stability is reported. The red emission, spanning the wavelength range of 600–800 nm, matches the absorption range of chlorophyll a, b and phytochrome (P r ). Its good thermal stability at 150 °C is in addition to its emission intensity, which is 81.7 % of its room-temperature intensity. Co-doping with Ca 2+ contributes to a 1.7-fold increase in the red emission intensity at room temperature. The encapsulation of the present phosphor onto UV LED chips produces red emitting LED devices, which can be used for garlic and corn cultivation. The implementation reveals that the six-hour artificial red light illumination supplement is the most effective and significant means to promote garlic and corn growth. The as-obtained red-emitting phosphor may be a promising candidate for pc-LEDs promotion of crop growth in agricultural factories.
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高影响因子
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