Remote Sensing
·
2021
·Vol. 13
·期 16
·3311
·
IF 4.848
Alejandro Sánchez de Miguel,Jonathan Bennie,Emma Rosenfeld,Simon Dzurjak,Kevin J. Gaston
The global spread of artificial light is eroding the natural night-time environment. The estimation of the pattern and rate of growth of light pollution on multi-decadal scales has nonetheless proven challenging. Here we show that the power of global satellite observable light emissions increased from 1992 to 2017 by at least 49%. We estimate the hidden impact of the transition to solid-state light-emitting diode (LED) technology, which increases emissions at visible wavelengths undetectable to existing satellite sensors, suggesting that the true increase in radiance in the visible spectrum may be as high as globally 270% and 400% on specific regions. These dynamics vary by region, but there is limited evidence that advances in lighting technology have led to decreased emissions.Keywords:ALAN;artificial light at night;astronomy;DMSP;LEDs;light pollution;melatonin;nocturnal ecology;VIIRS
研究领域:
环境科学
·
生物学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Xiaoyu Wang,Yadan Feng,Li Zhang,Iryna Protsak,Raiyanur Jamali,Yanxiang Shu,Preeti Pal,Zhen Wang,Jintao Yang,Dong Zhang
Development of ultraviolet (UV) curing technique has greatly expanded the preparation and application of polymer composite coatings due to its unique characteristics of high efficiency curing and controllable operation. However, the inevitable hazards of high pressure mercury lamps , as well as difficulty resulting from large amount of heat release when coating products, greatly limit the practical application and development of such curing coatings. Herein, a series of novel controllable, fast-cured coatings filled with high mineral contents were successfully designed and synthesized based on progressive ultraviolet light emitting diode (UV-LED) technology with ultra-low energy consumption. Due to the addition of a large number of opaque mineral particles, a new polymerization mechanism for the system was proposed and verified. Inorganic particle fillers (μm-level) can produce various degrees of reflective or refractive points, thus effectively reducing the barrier effect of the filling particles and realizing a much deeper solidification. Silver nanoparticles (AgNPs) were then combined with this composite material to fabricate a long-term antibacterial interior wall base-coating without interference with the curing effects. More importantly, the various effects of reactants of polymeric composite coatings with high inorganic mineral content for such UV-LED curing systems (365 nm) were brought to as comprehensive a conclusion as possible. This coating remained stable over a 15-week period against bacteria with the bactericidal coefficient of approximately 99.5% for E. coli and about 97% for S. aureus . We believe that proposed applicable polymerization mechanism will greatly enrich the current UV polymerization system, especially for polymer composite material with high mineral contents, and our designed wear resistance, high-hardness, and long-term antibacterial coating will also have great application prospects in many practical fields.
研究领域:
材料科学
·
生物医学工程
·
聚合物化学
✓ 已验证
产品关联
DOI
高影响因子
Optics
·
2025
·Vol. 7
·期 1
·1
·
IF 1.6
Chenxing Liao,Huihuang Cai,Jiabao Wu,Wei Xie,Liaolin Zhang
Mn4+-activated fluoride phosphors possess outstanding luminescent properties, making them highly suitable for applications in lighting and display technologies. However, the synthesis of such phosphors generally requires the use of large amounts of highly toxic aqueous HF, leading to serious environmental pollution. To eliminate the use of hazardous HF solution, a low-temperature molten salt method employing NH4HF2was developed to synthesize the narrow-band red emitter Cs2GeF6: Mn4+phosphor. Following the reaction, the product was washed with a dilute H2O2solution to remove residual NH4HF2and other impurities. The phase purity and morphology were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively, and the luminescence properties were examined via photoluminescence (PL) spectroscopy. The obtained phosphors exhibit bright red emission characteristics of Mn4+under blue-violet excitation. Among them, Cs2GeF6: 0.08 Mn4+shows the highest emission intensity, with an internal quantum efficiency (IQE) of 78%. A white light-emitting diode (WLED) fabricated by combining this phosphor with a blue chip and commercial Y3Al5O12: Ce3+(YAG) phosphor achieved a high luminous efficacy (LE) of ~146 lm/W, a correlated color temperature (CCT) of ~4396 K, and a color rendering index (Ra) of ~83, alongside excellent operational color stability.
研究领域:
材料科学
·
光电子学
·
固态化学
·
发光材料
·
LED技术
✓ 已验证
产品关联
DOI
高影响因子
Solids
·
2025
·Vol. 6
·期 4
·66
·
IF 2.4
Chenxing Liao,Feng Zhou,Wei Xie,Liaolin Zhang
Mn4+-doped fluoride red phosphors are widely used in white LED lighting and display applications due to their excellent luminescent properties. However, their synthesis relies heavily on highly toxic aqueous hydrofluoric acid, which not only causes severe environmental and soil/water pollution but also makes it difficult to control the microstructure of the products due to the rapid reaction rate. In this study, low-melting-point NH4HF2was used as the molten salt, with KMnO4and MnF2as manganese sources, to synthesize the red phosphor K3AlF6: Mn4+via the molten salt method. After the reaction, impurities such as NH4HF2were removed by washing with a dilute H2O2solution. The microstructure, photoluminescence properties, thermal quenching behavior, and application in warm white light-emitting diodes (W-LEDs) of the K3AlF6: Mn4+phosphors were investigated. The results indicate that the phosphors prepared by this method consist of a single pure phase. By adjusting the molten salt content, the morphology of the product can be transformed from nanoparticle-like to nanorod-like structures. All products exhibit the characteristic red emission of Mn4+under blue and violet light excitation, with the optimally doped sample achieving an internal quantum efficiency (IQE) of 69% under blue light excitation. The combination of the obtained K3AlF6: Mn4+with the yellow phosphor YAG enabled the fabrication of W-LEDs. These W-LEDs achieved a color rendering index (Ra) of 86.8, a luminous efficacy (LE) of 77 lm/W, and a correlated color temperature (CCT) of 3690 K, along with excellent color stability under operating conditions.
研究领域:
材料科学
·
光电子学
·
固态化学
·
发光材料
·
LED技术
✓ 已验证
产品关联
DOI
高影响因子
Journal of Physical Chemistry C
·
2015
·
IF 4.772
Lili Wang,Hyeon Mi Noh,Byung Kee Moon,Sung Heum Park,Kwang Ho Kim,Jinsheng Shi,Jung Hyun Jeong
Dual-mode excitation properties were introduced in Sm3+ doped Sr2CaMoO6 prepared by a high temperature solid state reaction technique. Two ways are available to generate white light in the single-component phosphor activated by Sm3+ ions. Warm white light can be obtained from Sr1.995Sm0.005CaMoO6 phosphor pumped by 380 or 411 nm excitation energy. The full visible spectral emission of the single-phase phosphor comes from the high and low level emission lines of Sm3+ ions as well as the intrinsic luminescence of MoO6 group. It is also competitive as yellow-emitting phosphor for blue pumped white LEDs and gives three emission bands at 567, 603, and 650 nm, presenting yellow luminescence upon 466 nm radiation. The 650 nm red emission band corresponding to 4G5/2 → 6H9/2 transition of Sm3+ can make its color rendering index better. The excellent photoluminescence of Sr2CaMoO6 is related to the partial tilting CaO6 octahedral and the lowered symmetry were confirmed by General Structure Analysis System. Band gap of Sr2CaMoO6 estimated from the diffuse reflection spectra and also calculated by CASTEP mode shows its semiconducting character. All the results show that the Sr2–xSmxCaMoO6 phosphors have considerable potential for applications in near UV LED or pumped by blue LED chip.
研究领域:
材料科学
·
光学材料
·
光子学
·
固态化学
·
发光材料
·
LED技术
✓ 已验证
DOI
高影响因子
ACS Applied Optical Materials
·
2024
·
IF 0
Jinxuan Sun,Wei Wang,Hanrui Liao,Yi Wei,Guogang Li
Superior thermal stability is an essential property of phosphor materials for their practical applications in the white-light-emitting diode (pc-WLED) lighting area. Nevertheless, the development of thermally stable red phosphor remains a challenging issue due to the serious nonradiative transition loss. In this work, a series of red-emitting Eu2W3–xMoxO12 (0.0 ≤ x ≤ 3.0) solid-solution phosphors were synthesized based on high-temperature solid-phase reaction. Surprisingly, the thermal stability property is obviously improved by designing a cationic substitution strategy and adjusting the annealing temperature. Under near-ultraviolet light excitation (395 nm), the emission intensity of Eu2W3O12 and Eu2Mo3O12 at 125 °C is 0.63 and 1.36 times of that at 25 °C, respectively. The emission intensity of Eu2Mo3O12 at 125 °C is increased to 2.16, which exhibits more competitive thermal stability than Eu2W3O12. This unique antithermal quenching enhancement phenomenon is ascribed to the decreased thermal ionization and thermally activated crossover effect energy, resulting from the simultaneously increased optical band gap and activation energy via the cationic substitution strategy. This work proposes a strategy to optimize the thermal stability behavior of red phosphors in pc-WLED applications.
研究领域:
材料科学
·
光学材料
·
固态化学
·
光子学
·
LED技术
✓ 已验证
DOI
Science of Advanced Materials
·
2017
·
IF 1.671
Zheng Jiayu,Li Liyi,Peng Mingying
Unusually, valent Bi2+ ions doped into solids can exhibit near ultraviolet or blue excitation and red emissions. Previously the ion has only been found stabilized in compounds such as borate, sulfate or phosphate, and has not yet been reported in other types of compounds.
In this work, we found that Bi2+ can also survive in CaAl12O19. Time resolved emission spectra reveal that there are two types of Bi2+ ions in the compound due to the substitution of calcium lattice sites. Both types of Bi2+ ions show
blue excitations and red emissions, with energy transfer occurring from the longer wavelength emission center to the shorter wavelength emission center. As bismuth content x increases, Bi2+ luminescence intensifies at first, but is then quenched afterwards when x exceeds
0.3 mol%. The dominant mechanism of quenching was found to be due to electric quadrupole–quadrupole rather than exchange interactions. This work suggests that CaAl12O19:Bi2+ is a potential red phosphor for application in white light LEDs (WLEDs).
研究领域:
材料科学
·
光学材料
·
固态化学
·
光子学
·
LED技术
✓ 已验证
DOI
高影响因子
DALTON TRANSACTIONS
·
2017
·Vol. 46
·期 20
·6776-6784
·
IF 4.029
G. Q. Wang,X. H. Gong,Y. J. Chen,J. H. Huang,Y. F. Lin,Z. D. Luo,Y. D. Huang
Two novel red phosphors KBaEu(XO4)3 (X = Mo, W) have been synthesized by high-temperature solid-state reactions and the crystal structures were determined for the first time. Single-crystal X-ray diffraction data reveal that their space groups are C2/c. The crystalline structure is constituted of K/BaO8 distorted square antiprisms and distorted EuO8 polyhedra which form chains lying along the c-axis and two kinds of distorted XO4 tetrahedra. This high disorder of K/Ba which might lower the crystal field symmetry around Eu3+ results in the high purity of red emission around 615 nm originating from 5D0 → 7F2 transition under near-ultraviolet (NUV) excitation. With increasing temperature, the luminescence of KBaEu(XO4)3 (X = Mo, W) phosphors decreases almost linearly with subtle alteration for the CIE coordinate. As the temperature reaches 550 K, the red emission intensity decreases to 37.3% and 50.7% of that at 300 K for KBaEu(MoO4)3 and KBaEu(WO4)3, respectively. The analysis of the decay curves of the 5D0 → 7F2 emission at variable temperatures indicates the weak cross relaxation and non-radiative energy transfer between Eu3+ ions. These results demonstrate that the investigated phosphors are attractive for application in high power NUV excited white LEDs.
研究领域:
材料科学
·
发光材料
·
固态化学
·
光学材料
·
LED技术
✓ 已验证
DOI
高影响因子
Materials Science and Engineering B-Advanced Functional Solid-State Materials
·
2016
·
IF 2.331
B.Y. Huang,B.L. Feng,L. Luo,C.L. Han,Y.T. He,Z.R. Qiu
Novel Sr 3 Y(PO 4 ) 3 :Dy 3+ , Eu 3+ (SYP:Dy 3+ , Eu 3+ ) phosphors were synthesized by a standard solid-state reaction under an ambient air atmosphere and their structural and optical properties were investigated. XRD and diffuse reflectance spectra (DRS) were used to explore structural properties. The former showed that single phase phosphors were obtained and that the rare earth ions entered into the cubic host by substituting the smaller Y 3+ ions and thereby enlarging the unit cell. The DRS indicated that the host has a direct bandgap of 4.5 eV. Under 393 nm excitation, a strong and stable warm white light emission with high color purity was achieved in SY 0.92 P:0.06Dy 3+ , 0.04Eu 3+ . The energy transfer from Dy 3+ to Eu 3+ ions was investigated and the related mechanism was discussed based on the optical spectra and emission decay curves. The thermal quenching of emission is similar to that of YAG:0.06Ce 3+ . The results show the single phase phosphor is potential in warm white LED.
研究领域:
材料科学
·
光学材料
·
光子学
·
固态化学
·
LED技术
✓ 已验证
DOI
高影响因子
JOURNAL OF LUMINESCENCE
·
2016
·
IF 2.693
Yiru Wang,Xiaohua Liu,Pengfei Niu,Lindan Jing,Weiren Zhao
Novel Eu 3+ activated Gd 2 Mo 4 O 15 phosphors were synthesized at the comparatively low temperature of 700 °C via solid-state reaction. X-ray powder diffraction results demonstrate that the phosphors crystallize in the triclinic crystal structure, the space group P I ¯ . The photoluminescence spectra and ultraviolet-visible (UV–vis) reflectance and transmittance spectra indicate that Eu 3+ doped Gd 2 Mo 4 O 15 phosphors show a broad and strong absorption band covering ultraviolet (UV) and near ultraviolet (NUV) regions and the crystals emit red light with peak maximum at about 618 nm under excitation of UV, NUV or blue light. The optimal doping concentration of Eu 3+ ions in Gd 2 Mo 4 O 15 phosphors is around 50 mol% and the main concentration quenching mechanism is determined to be the exchange interaction.
研究领域:
材料科学
·
光学材料
·
荧光粉化学
·
LED技术
·
固态照明
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry C
·
2023
·Vol. 11
·期 11
·3865-3874
·
IF 6.4
Sheng Wu,Shanshan Hu,Quan Liu,Shuai Zhang,Dongliang Jiang,Guoxing Zhang,Yakun Le,Yao Xiao,Binli Xiao,Puxian Xiong,Yan Chen,Yinzhen Wang
Luminous properties play an essential role in phosphor-converted white light-emitting diodes for high-quality illumination, where the self-reducing behavior of doped activators and their excellent thermal stability have received significant attention. Here, we prepared NaY9Si6O26:Mn2+ red phosphors by a high-temperature solid-state reaction method, which achieved self-reduction of Mn4+ → Mn2+ and excellent thermal stability (luminous intensity at 420 K is 98% of that at room temperature) under ambient conditions. First-principles calculations and X-ray photoelectron spectroscopy elucidated a self-reduction mechanism from Mn4+ to Mn2+. The defect types were calculated in conjunction with thermoluminescence, verifying that the low thermal quenching properties originated from the transfer of electrons from the defect energy level to the Mn2+ excited state center induced by the cationic vacancy defect, which suppressed the luminescence loss from thermal quenching. In this work, the effect of defects on luminescence properties is highlighted and the further exploration of defect control is stimulated, opening up a new avenue for new types of highly thermally stable materials.
研究领域:
材料科学
·
光子学
·
固态化学
·
发光材料
·
LED技术
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry C
·
2019
·Vol. 7
·期 36
·11220-11226
·
IF 6.641
Binbin Su,Maxim S. Molokeev,Zhiguo Xia
To discover new narrow-band green-emitting phosphors is a challenge for backlighting light-emitting diodes (LEDs) used in liquid crystal displays (LCDs). The synthesis and optical properties of Cs3MnBr5 are demonstrated herein. The intrinsic Mn2+ luminescence without concentration quenching leads to intense green emission at 520 nm with narrow full width at half maximum of 42 nm and high photoluminescence quantum yield (PLQY) of 49% under the excitation at 460 nm. When a small amount of Zn2+ is introduced into Cs3MnBr5, the luminescence intensity decreases slightly. However, the thermal stability of Cs3MnBr5 is improved from 82% to 87% with the intensity values at 423 K compared to that at 298 K. The white LED device fabricated using Cs3Mn0.96Zn0.04Br5 (green) and K2SiF6:Mn4+ (red) phosphors with a blue LED chip exhibit a high luminous efficiency (107.76 lm W−1) and wide color gamut (101% National Television System Committee standard (NTSC) in Commission Internationale de L’Eclairage (CIE) 1931 color space), demonstrating its potential application in wide color gamut LCD backlights.
研究领域:
材料科学
·
光学材料
·
固态照明
·
荧光粉化学
·
LED技术
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）