CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Shihang Zhang,Liying Zhang,Haipeng Ji
Mn 4+ -activated fluoride phosphors, exemplified by K 2 SiF 6 :Mn 4+ , exhibit exceptional narrow-band red emission but suffer from severe hydrolysis-driven degradation, significantly limiting their operational longevity. This study systematically investigates the stepwise degradation of K 2 SiF 6 :Mn 4+ upon water exposure, uncovering new insights into its hydrolytic behaviour. Upon immersion, the phosphor suspension undergoes a browning-clearing transition, attributed to the hydrolysis of [MnF 6 ] 2– which generates black suspended MnO 2 that temporarily darkens the solution before sedimentation. The degradation process involves two sequential stages: an initial rapid dissolution-dissociation of K 2 SiF 6 :Mn 4+ , accompanied by a sharp pH decrease, followed by relatively slower hydrolysis of [MnF 6 ] 2– and [SiF 6 ] 2– yielding crystalline MnO 2 and amorphous H 2 SiO 3 . Besides, upon reaching dissolution-ionization equilibrium, the released K + , [SiF 6 ] 2– , and [MnF 6 ] 2– ions would nucleate and precipitate, forming crystalline K 2 SiF 6 and K 2 SiF 6 :Mn 4+ particles with much smaller size compared to the original K 2 SiF 6 :Mn 4+ . Notably, this study reveals that the degradation of K 2 SiF 6 :Mn 4+ is significantly accelerated under both blue and UV light illumination, with UV light inducing faster degradation. These findings provide fundamental insights into the hydrolysis-driven degradation mechanism of Mn 4+ -activated fluoride phosphors, offering a scientific basis for developing strategies to enhance their stability and extend their service life.
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Science China-Materials
·
2025
·
IF 7.4
Yang Chen,Tan Yuhuan,Li Zheyi,Liang Shan,Guan Xi-Hua,Yang Zhong-Jian,Lian Shixun,Zhou Wenli
The reduction in photoluminescence efficiency due to crystallite downsizing is a significant issue in Mn 4+ -doped fluoride nanomaterials, crucial for their application in full-color micro-LED displays. This study presents a strategy to enhance the photoluminescence efficiency of K 3 AlF 6 :Mn 4+ nanocrystals (NCs) by incorporating Mg 2+ for charge compensation and utilizing the plasmonic effect of Au nanorods. We found that Mg 2+ incorporation effectively reduced lattice defects, increasing photoluminescence intensity by 17% and internal quantum efficiency from 22.37% to 27.56%. Fabricating Au@SiO 2 /fluoride nanocomposites, we investigated how the SiO 2 spacer layer thickness, Au@SiO 2 resonance wavelength, and relative concentration affect photoluminescence properties. Optimizing the balance between Purcell and Förster resonance energy transfer effects further increased photoluminescence intensity by 25%, internal quantum efficiency to 32.09%, and external quantum efficiency from 14.20% to 18.05%. Additionally, we assessed the potential application of these nanocomposites in micro-LED display technology by examining nanocomposite-PMMA films. This work provides insights into the development of highly efficient red-emitting nanomaterials.
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CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Jianing Wang,Hongcai Yu,Yunhui Min,Shulin Chen,Xiaotian Li,Ruihong Liang,Zhiyong Zhou,Bin Yang
Calcium bismuth niobate (CBN), known for its high Curie temperature ( T C ), has been investigated as a potential material for vibration sensor due to its ability to operate at elevated temperatures. However, the inherent weakness in piezoresponse of CBN has limited its sensing performance. In this study, a pseudo-tetragonal distortion in CBN was successfully induced by incorporating Ce 3+ ions into the (Bi 2 O 2 ) 2+ layers of CBN. This modification led to a change in the interaction between the perovskite and bismuth layers, resulting in enhanced piezoelectric and ferroelectric properties. Further enhancement was achieved by introducing Mn 4+ ions into the Ce 3+ -doped CBN. The co-doped CaBi 1.96 Ce 0.04 Nb 1.985 Mn 0.015 O 9 demonstrated a significantly improved piezoelectric coefficient ( d 33 ) of 15.9 pC/N, compared to 6.8 pC/N for pure CBN ceramics, and an increased remnant polarization ( P r ) of 20.78 μC/cm 2 , compared to the 3.83 μC/cm 2 of the pure material. This work not only deepens the understanding of bismuth-layer-structured ferroelectrics (BLSFs) but also presents a viable co-doping strategy to enhance the piezoresponse in CBN ceramics. This strategy could pave the way for the development of high-performance, high-temperature vibration sensors and potentially lead to the discovery of more novel BLSFs with superior performance.
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ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Yufan Wei,Qianxing Huang,Shijie Yu,Qiyue Shao,Jianqing Jiang
The K2SiF6:Mn4+ (KSFM) phosphor featuring efficient ultranarrow red emissions is an outstanding candidate for white light-emitting diode (WLED) applications. However, poor moisture resistance seriously affects its application performance. In this study, a two-step surface reconstruction strategy is proposed to dramatically enhance the moisture resistance of commercially available KSFM phosphors, involving treatment with H2NbF7 and subsequent hydrothermal treatment. The modified KSFM phosphor exhibits a high internal quantum efficiency (IQE) of 98.9% after the two-step surface treatment. Meanwhile, nearly 100% of the initial emission intensity is retained for the modified KSFM phosphor even after aging in high temperature (85 °C) and high relative humidity (85% RH) environments for 6 days, in sharp contrast to only 18.6% retention for the original KSFM phosphor. The relative emission intensity of the modified KSFM remains at 98.9% even after being immersed in water for 6 h. Additionally, the phosphor-converted LED fabricated with the modified KSFM phosphor demonstrated excellent long-term stability, retaining up to 97.9% of initial luminous efficacy after aging under 85 °C and 85% RH conditions for 500 h. The moisture-resistance mechanism is elucidated on the basis of spectroscopic analysis as well as structural and compositional characterization of the phosphor surface layer, which can be attributed to the formation of a robust Mn4+-rare shell with high crystalline quality following this two-step surface treatment. The findings contribute to the performance improvements of KSFM phosphors for industrial applications.
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高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Wanguo Liu,Fuyu Chen,Xiaogen Zhan,Peichang Ouyang
The developments of science and technology have made greenhouse plant cultivation increasingly valued, which has made the research on light sources of great significance, causing that deep-red-emitting phosphors have particular research prospects. In this work, Li 1.6 Mg 1.6 Sn 2.8 O 8 :Mn 4+ under high-temperature solid-state method is synthesized in air and Li 1.6 Mg 1.6 Sn 2.8 O 8 :Mn 4+ @PDMS film is prepared. Li 1.6 Mg 1.6 Sn 2.8 O 8 :Mn 4+ at room temperature shows deep-red emission in the range of 600 – 800 nm with photoluminescence (PL) peaks at ∼660 and 672 nm because of the 2 E g → 4 A 2g transition of Mn 4+ ion in octahedron [MnO 6 ] when it is excited by light from ultraviolet to green (250–540 nm). PL spectra of Li 1.6 Mg 1.6 Sn 2.8 O 8 :Mn 4+ under different excitation wavelength and the time-resolved PL spectra at room temperature are investigated, which confirm one luminous center (Mn 4+ ). The good thermos-stability is proved by the temperature-dependent PL spectra. The potential applications of Li 1.6 Mg 1.6 Sn 2.8 O 8 :Mn 4+ in plant growth lighting and polymer luminescent film are explored via absorption spectra of plants, PL spectrum of Li 1.6 Mg 1.6 Sn 2.8 O 8 :Mn 4+ , and Li 1.6 Mg 1.6 Sn 2.8 O 8 :Mn 4+ @PDMS film.
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ChemistrySelect
·
2025
·Vol. 10
·期 17
·e202500785
·
IF 2
Jing Wang,Xingke Zheng,Jiaqi Gao,Yue Luo,Zhe Jiang
Graphical This study reports the synthesis of Ca 2 La(Ta,Mn)O 6 double perovskite red emitters, exhibiting strong red emission at 691 nm, with excellent thermal stability and UV excitation. A wireless power transfer system demonstrates adjustable luminescence under various voltages and frequencies, positioning this material as a promising candidate for indoor lighting and noncontact circuits. The rapid adoption of light emitting diodes technology stems from its high efficiency, long lifespan, and energy-saving capabilities. However, achieving high-quality white light emitting diodes, particularly through the integration of efficient red emitters, remains a significant challenge. This study reports the synthesis of Ca₂La(Ta,Mn)O₆ double perovskite red emitters via high-temperature solid-state reactions. The material exhibits a strong red emission peak at 691 nm, attributed to Mn⁴⁺ ions at symmetrical [TaO₆]⁷⁻ octahedral sites, confirmed by g = 2.008 in electron paramagnetic resonance spectroscopy. The UV excitation spectrum (250–600 nm) and thermal stability were analyzed, showing a retained optical intensity of 41% at 423 K. Additionally, a red emitter was developed, and a noncontact LCC-S wireless power transfer driving system was constructed. The system demonstrated adjustable luminescence under varying input voltages (4–7.3 V) and frequencies (90–110 kHz), highlighting its potential for dynamic lighting applications. These findings suggest Ca 2 La(Ta,Mn)O 6 double perovskite as a promising candidate for indoor lighting and noncontact circuit systems.
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JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
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2025
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IF 4.7
Yue Zhong,Yang Li,Tao Su,Jing Xie,Xianze Li,Wenming Wang,Yan Pan,Xiantao Wei,Yong Li
The advancement of modern artificial plant cultivation necessitates the development of high-performance red-light sources precisely tailored to plant spectral absorption profiles. Such sources are crucial for improving crop yield and quality in contemporary agricultural practices. In this study, a far-red-emitting double perovskite phosphor LaLi 0.333 Ti 0.667 O 3 : Mn 4+ was successfully synthesized via a facile solid-state reaction method. Systematic investigations were conducted on the crystal structure, luminescent properties, and decay characteristics of the phosphor. Under 355 nm excitation, the optimized LaLi 0.333 Ti 0.667 O 3 : 0.3 mol% Mn 4+ phosphor demonstrates a prominent far-red emission peak at 726 nm, along with exceptional thermal stability, retaining 48.7 % of its room-temperature intensity at 420 K. Thermal quenching analysis yielded an activation energy (ΔE) of 0.388 eV. Remarkably, this phosphor achieves an ultrahigh internal quantum yield (QY) of 47 % within the 650–850 nm spectral range. The fabricated phosphor-converted light emitting diode (pc-LED) device exhibits precise spectral congruence with phytochrome far-red (P fr ) absorption (730 nm), indicating significant potential for photomorphogenetic regulation in agricultural applications through supplementary lighting strategies. Furthermore, due to its superior tissue penetration capability, this phosphor also shows promise for applications in non-invasive medical diagnostics.
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JOURNAL OF POWER SOURCES
·
2024
·
IF 8.1
Yixuan Zhang,Guo-Qiang Liu,Danlei Qiao,Jiaguan Chen,Qiang Sun,Lei Wen
This work focuses on the effect of the of Mn 3+ /Mn 4+ ratio in the reactants on the structure and electrochemical properties of NaMn 0.9 Cu 0.1 O 2 cathode materials for sodium-ion batteries. By systematically varying the manganese valence states in the reactants, we observed a phase transition from the β-phase to the P2-phase with increasing Mn 3+ concentrations in the reactants, contrary to the expected favorability of the β-phase at higher Mn 3+ levels. This finding suggests a complex interplay between the valence states of the reactants and phase formation mechanisms, which needs further investigation. Additionally, electrochemical testing indicated that the phase composition significantly impacts the electrochemical performance of the material. Specifically, the M0 sample, possessing the optimal P2/β ratio, exhibited excellent electrochemical performances, achieving a high initial discharge capacity of 155.1 mA h g −1 and remains 88.1 % after 40 cycles. These results emphasize the importance of precursor selection and valence management in the development of high-performance cathode materials for sodium-ion batteries.
研究领域:
材料科学
·
电化学
·
能源存储
·
无机化学
·
固态化学
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高影响因子
DALTON TRANSACTIONS
·
2017
·Vol. 46
·期 30
·9925-9933
·
IF 4.029
L. Y. Wang,E. H. Song,T. T. Deng,Y. Y. Zhou,Z. F. Liao,W. R. Zhao,B. Zhou,Q. Y. Zhang
Herein, a Mn4+ ion doped complex ternary-alkaline fluoride red phosphor K2NaAlF6:Mn4+ has been synthesized through a facile two-step co-precipitation method at room temperature. The crystal structure, morphological properties and influence of the dopant concentration, temperature and humidity on luminescence properties as well as the performance of the as-synthesized phosphor used in white light emitting diodes (WLEDs) were investigated carefully. Intense absorption in the blue region (∼460 nm) and bright narrow-band red emission (∼630 nm) with high color purity were observed from this resultant powder. Temperature-dependent investigation and reliability examination in a HTHH environment (85 °C high temperature and 85% high humidity) indicate that the obtained ternary-alkaline fluoride phosphor K2NaAlF6:Mn4+ presents more exceptional thermal quenching behavior and longevity compared to some other binary-alkaline fluorides. Moreover, using K2NaAlF6:Mn4+ as a red light component, a warm WLED with a preferable color rendering index (Ra = 85.5) and luminous efficacy (LE = 91.2 lm W−1) as well as a low corresponding color temperature (CCT = 3650 K) is easily achieved, further revealing the great potential of the as-prepared ternary-alkaline fluoride red phosphor K2NaAlF6:Mn4+ for WLED applications.
研究领域:
材料科学
·
光学工程
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OPTICAL MATERIALS
·
2025
·
IF 4.2
Chen-Yang Qi,Dan Zhao,Rui-Juan Zhang,Qing-Xia Yao
Mn 4+ has garnered significant global interest due to its application in red light emission, particularly within the realm of plant growth lighting. However, there are relatively few studies focusing on the incorporation of Mn 4+ into titanate materials. In this research, we synthesized a series of Ba₆Y₂Ti 4-x O₁₇ (BYT: x Mn⁴⁺) phosphors with varying concentrations of Mn 4+ using a high-temperature solid-state synthesis method. Initially, we confirmed the structural integrity and phase purity of the samples through X-ray diffraction (XRD) analysis and refinement techniques. The experimental results indicate that under near-ultraviolet (UV) excitation, these phosphors emit far-red light at approximately 700 nm. Furthermore, their emission spectra align closely with the spectral requirements of chlorophyll and photoreceptive pigments (P r and P fr ), which are essential for optimal plant growth. This characteristic makes them promising candidates for plant cultivation applications. Consequently, we posit that BYT:0.015Mn⁴⁺ represents a novel titanate-based far-red emitting material with considerable potential for use in LED lighting systems designed for plant growth particularly in enhancing photosynthetic efficiency and promoting overall plant development.
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JOURNAL OF MOLECULAR STRUCTURE
·
2026
·
IF 4.9
Yingfang Li,Long Tian,Qingzhe Wu,Xiaohuan Long,Hai Wu,Chaoyong Deng,Weichao Huang
Mn 4+ -doped oxide phosphors with deep-red emission show significant application potential in plant-growth LEDs. In this study, double perovskite Ba 2- x Sr x GdSbO 6 : Mn 4+ deep-red phosphors were developed via a cation substitution strategy. The crystal structure, optical properties, and thermal stability of the phosphors were investigated in detail. The as-prepared phosphors showed an intense deep-red emission band around 625–750 nm. Cationic substitution with Sr 2+ significantly improved the luminescence performance of the Ba 2 GdSbO 6 : Mn 4+ phosphors, and the optimized sample BaSrGdSbO 6 : Mn 4+ was obtained, achieving a nearly 12-fold enhancement in emission intensity. Furthermore, the electroluminescence (EL) spectrum of the prototype LED device fabricated based on the BaSrGdSbO 6 : Mn 4+ phosphor is matched well with the absorption band of plant pigments. These findings demonstrate that the BaSrGdSbO 6 : Mn 4+ phosphors have potential applications in plant-growth LEDs, and also provide some guiding inspirations in the exploration of novel Mn 4+ -doped double perovskite phosphors.
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NEW JOURNAL OF CHEMISTRY
·
2020
·Vol. 44
·期 16
·6163-6172
·
IF 3.288
Dayu Huang,Peipei Dang,Xiao Xiao,Biao Bai,Hongzhou Lian,Qingguang Zeng,Jun Lin
It is necessary to develop novel high-efficiency red or far-red-emitting LEDs in order to facilitate the phosphor-converted light-emitting diodes (pc-LEDs) for plant growth. This work reports a series of novel far-red emitting (Ba,Sr)LaZnTaO6:xMn4+ phosphors with double perovskite structure synthesized by the traditional high-temperature solid-state reaction (SSR). The crystal structure and morphology of (Ba,Sr)LaZnTaO6 were investigated by high-resolution TEM, SEM, and XRD Rietveld refinement. The photoluminescence properties were systematically explored and analyzed by diffuse reflectance (DR) spectra, photoluminescence emission (PL) and excitation (PLE) spectra, decay curves, and temperature-dependent spectra. Mn4+ ions occupy Ta5+ sites located at the [TaO6] octahedral emitting red light with the peak at 698 nm in BaLaZnTaO6:Mn4+ and 695 nm in SrLaZnTaO6:Mn4+ under n-UV and blue light excitation. The critical quenching concentration of Mn4+ was determined to be 0.008. The concentration quenching mechanism could be a dipole–dipole interaction between the Mn4+ ions. In addition, the PL intensity of (Ba,Sr)LaZnTaO6:xMn4+ phosphors decreases with increasing temperature. The SrLaZnTaO6:xMn4+ sample has better thermal stability than BaLaZnTaO6:xMn4+. Interestingly, (Ba,Sr)LaZnTaO6:0.008Mn4+ exhibits outstanding internal quantum efficiency (IQE ≥ 80%). Finally, the fabricated LEDs were combined with SrLaZnTaO6:0.008Mn4+ phosphors combined with 460 nm InGaN chips, which emit blue and red light. Based on the above properties, the rare-earth-free (Ba,Sr)LaZnTaO6:xMn4+ phosphors have great potential in being applied as far-red emitting phosphors in high-power plant growth LEDS.
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