JOURNAL OF RARE EARTHS
·
2021
·Vol. 40
·期 11
·1691-1698
·
IF 3.712
Qingsong Hu,Zaifa Pan,Guijie Liang
White light-emitting diodes (WLEDs) fabricated by single-phase full color emitting phosphor are an emerging solution for health lighting. The crystallographic site occupation of activators in a proper host lattice is crucial for sophisticated design of such phosphor. Here, we report a high quality white light-emitting phosphor Ba 2 Ca(BO 3 ) 2 :Ce 3+ (K + ),Eu 2+ ,Mn 2+ with spectral distribution covering whole visible region. Blue light emission originates from Ce 3+ ions occupying preferentially Ba 2+ site by controlling synthesis conditions. Green and red lights are obtained from Eu 2+ occupying Ba 2+ (and Ca 2+ ) site and Mn 2+ occupying Ca 2+ site, respectively. In this triple-doped phosphor, strong red emission with a low concentration of Mn 2+ is realized by the efficient energy transfer from Ce 3+ and Eu 2+ to Mn 2+ . Furthermore, high quality white light is accomplished by properly tuning the relative doping amount of Ce 3+ (K + )/Eu 2+ /Mn 2+ based on efficient simultaneous energy transfer. The results indicate that Ba 2 Ca(BO 3 ) 2 :Ce 3+ (K + ),Eu 2+ ,Mn 2+ is a promising white light-emitting phosphor in WLEDs application.
研究领域:
材料科学
·
无机化学
·
发光材料
·
固态照明
·
能源材料
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Xiaoyuan Chen,Xiaoyong Huang
Lighting and display technologies are revolutionized by the invention of YAG:Ce 3+ phosphors driven by InGaN blue light-emitting diode (LED). Yet, the faint emission components in the red spectral region from typical LED devices can cause circadian rhythm disorders and aesthetic fatigue of the human eye. Developing broadband orange-emitting phosphor with abundant red coverage is one of the approaches for addressing this challenging problem. Herein, an innovative ultra-broadband orange-emitting Mg 2.5 Y 1.5 Al 1.5 Si 2.5 O 12 :Ce 3+ (MYASO:Ce 3+ ) garnet phosphor is successfully reported to bridge the above gap. The representative MYASO:4%Ce 3+ sample exhibits an unexpectedly luminescence band with the full width at half maximum (FWHM) of up to 155 nm, the high thermal robustness (58%@423 K), and satisfactory internal quantum efficiency of 67% upon 465 nm blue light excitation. Such a large FWHM value results from the occupation of a single crystallographic site of Ce 3+ in the dodecahedral [YO 8 ] position of MYASO garnet host. Red-shift emission with respect to commercial YAG:Ce 3+ is mainly attributed to the cooperative effect of the enhanced crystal field strength and increased Stokes shift . The emission intensity reduction at the high-temperature environment of MYASO:4%Ce 3+ is derived from the enhancement of the thermal cross-relaxation associated with the larger Stokes shift (4839 cm −1 ). The resulting high-quality warm white LED device fabricated from the optimal MYASO:4%Ce 3+ sample shows a satisfactory color rendering index (CRI = 84), comfortable correlated color temperature (CCT = 4032 K) and an excellent luminous efficacy (LE = 58.7 lm W −1 ) under a 60 mA drive current. These findings stimulate the exploration of ultra-broadband orange-emitting phosphors with abundant red emission to fabricate high-CRI warm-white LEDs for healthy solid-state lighting.
研究领域:
材料科学
·
光学工程
·
固态照明
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Wei Li,Nan Ma,Balaji Devakumar,Xiaoyong Huang
In this work, novel highly efficient cyan-emitting Ce 3+ -activated CaLu 2 HfGaAl 3 O 12 (abbreviated as CLHGAO) garnet-structured phosphors were synthesized using the high-temperature solid-state reaction route. Rietveld refinement results demonstrate the as-prepared samples belong to cubic space group Ia 3 ‾ d . These CLHGAO: x Ce 3+ ( x = 0.5–8%) phosphors possessed a broad absorption band in the 320–450 nm wavelength range with a maximum at 408 nm. Upon 408 nm excitation, the CLHGAO:0.5%Ce 3+ sample showed a broad cyan emission band within 425–750 nm wavelength range (emission peak: 493 nm; bandwidth: 95 nm), along with CIE color coordinates of (0.1939, 0.3533) and a high internal quantum efficiency of 81.9%. It is observed that, with increasing Ce 3+ doping concentration from 0.5% to 8%, the emission peak position of CLHGAO: x Ce 3+ moves from 493 nm to 527 nm, and the corresponding emission color changes from cyan to green. Besides, the thermal stability and color stability of CLHGAO:0.5%Ce 3+ phosphor at high temperature are also studied. A white LED device was fabricated by utilizing a 395 nm LED chip with as-prepared CLHGAO:0.5%Ce 3+ cyan-emitting phosphor and commercial (Ba,Sr) 2 SiO 4 :Eu 2+ green-emitting phosphor and commercial CaAlSiN 3 :Eu 2+ red-emitting phosphor, and it demonstrates a high-color-quality white light with high color rendering index of 91, low color correlated temperature of 3547 K and good luminous efficacy of 58.71 lmW −1 .
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 8.128
Nan Ma,Wei Li,Balaji Devakumar,Zongjie Zhang,Xiaoyong Huang
White light-emitting diodes (LEDs) are widely used in lighting and display devices, and the exploration of phosphors with excellent luminescence performance and good stability is the key to the development of white LEDs. In this work, we reported novel near-UV-excited green-emitting Ca 2 LuHf 2 (AlO 4 ) 3 :Ce 3+ ,Tb 3+ garnet phosphors with efficient Ce 3+ → Tb 3+ energy transfer. The CLHA:Ce 3+ ,Tb 3+ green phosphors were successfully synthesized by a high-temperature solid-state method, and the phosphors were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, elemental mapping, photoluminescence excitation and photoluminescence spectra, the Commission International de I’Eclairage (CIE) chromaticity coordinates, quantum efficiency and temperature-dependent emission spectra. Due to the spin-allowed 4f → 5d transition of Ce 3+ ions, the CLHA:Ce 3+ ,Tb 3+ phosphors exhibited a strong broad excitation band in the 300–470 nm near-ultraviolet (near-UV) range. Under 408 nm excitation, the CLHA:Ce 3+ ,Tb 3+ phosphors showed strong green light with emission center at 543 nm. The mechanism of energy transfer from Ce 3+ to Tb 3+ ions was attributed to quadruple-quadruple interaction. Impressively, the internal quantum efficiency and external quantum efficiency of the optimal CLHA:0.02Ce 3+ ,0.5Tb 3+ green phosphors were measured to be 77.1% and 55.8%, respectively. Finally, using the CLHA:0.02Ce 3+ ,0.5Tb 3+ phosphors as green-emitting color converter, a near-UV-pumped white LED device was fabricated, and under 80 mA driving current the LED device demonstrated bright warm-white light with high color rendering index (93.7), low correlated color temperature (3574 K), CIE chromaticity coordinates (0.3922, 0.3633), and high luminous efficacy (29.35 lm/W).
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2019
·Vol. 9
·期 23
·13201-13206
·
IF 3.049
Xu Yang,Maohui Yuan,Rui Wang,Xiaofan Zhao,Zining Yang,Kai Han,Hongyan Wang,Xiaojun Xu
Harnessing the color tuning capability of upconversion nanoparticles (UCNPs) is of great significance in the field of advanced bioimaging and color display. Here, we report the tunable size and upconversion luminescence (UCL) multicolor in CaF2:Yb3+/Ho3+/Ce3+ UCNPs, which were synthesized by a facile hydrothermal method. It was found that the size of these UCNPs could be controlled (from 600 to 30 nm) by varying the concentration of Ce3+ ions. Under the excitation of a 980 nm continuous-wave (CW) laser, the UCL color of these UCNPs can be tuned from green to red as the doped Ce3+ ions gradually increase from 0 to 10 mol% and the red-to-green (R/G) ratio is enhanced remarkably. It is suggested that the cross-relaxation (CR) processes between Ho3+ and Ce3+ ions contribute to the tunable multicolor and enhancement of the R/G ratio. The mechanism of these processes is well supported by the time-resolved decay and near infrared (NIR) emission measurements.
研究领域:
材料科学
·
生物成像
·
光学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Advanced Optical Materials
·
2024
·
IF 8
Min Zhang,Peipei Dang,Zixun Zeng,Dongjie Liu,Yujia Wan,Yi Wei,Hongzhou Lian,Guogang Li,Jun Lin
Development of ultra-broadband visible-to-near-infrared (VIS-NIR) luminescent materials is a challenging but rewarding endeavor, as they are highly desirable for a number of applications in photonics, optoelectronics, and biological sciences. Nevertheless, to date, rare earth-doped phosphors that can be efficiently excited by blue light and produce broadband emission in the VIS-NIR regions remain scarce. In this study, a series of Ce 3+ -doped Ba 3 M 4 O 9 (M = Sc, Lu, Y) broadband luminescent materials are designed based on low-coordination crystallographic lattice engineering. Among these materials, Ba 3 Y 4 O 9 :Ce 3+ produces a continuous ultra-wide VIS-NIR emission (λ em = 660 nm) in the range of 500–950 nm under 410 nm light excitation. This emission wavelength is the longest among those observed in Ce 3 ⁺-doped oxide materials. Structural refinement, theoretical calculation, and spectral analysis demonstrate that this VIS-NIR broadband emission is attributed to the occupying multiple distorted octahedral lattice sites by Ce 3+ in Ba 3 Y 4 O 9 . Several strategies are employed to enhance the luminescence intensity and thermal stability of this material, including the use of carbon paper coating, the incorporation of co-solvents, and the addition of GeO₂ or ZrO₂. Furthermore, the as-prepared materials demonstrate multifunctional applications in white light-emitting diodes (WLED), night vision, and fluorescent thermometers. This study offers insights into the design of Ce3+-doped ultra-wide VIS-NIR light-emitting materials.
研究领域:
材料科学
·
光学工程
·
晶体学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2021
·
IF 8.742
Ye Zhang,Yong Gao,Peng Wang,Yichen Xu,Zhenming Yang,Jinsong Zhang
Membrane contactors have received considerable attention for extraction due to non-dispersive mass transfer through porous membranes. The past decades have seen the rapid development of organic hollow fiber membrane contactors, but very few studies have explored the applications of inorganic membranes in extraction, possibly due to their high costs. In this work, a novel SiC foam material with a hollow skeleton and microporous strut wall was used as a ceramic membrane contactor (HS-FCMC) for rare earths extraction. The foam's structure was characterized by scanning electron microscopy (SEM), X-ray micro-computed tomography (micro-CT), and mercury intrusion porosimetry (MIP). The flow and concentration fields inside and outside the foam cell were simulated by computational fluid dynamics (CFD), and the mass transfer through the ceramic membrane was analyzed. Based on the nitric acid–Ce 3+ /Pr 3+ –P507–kerosene chemical system, the extraction efficiency of Pr 3+ and Ce 3+ using the HS-FCMC reached 96.13% and 92.86%, respectively. A comparison study with poly tetra fluoroethylene (PTFE) hollow fibers was also conducted. The results indicate that the HS-FCMC is suitable for rare earths extraction due to the multiscale porous structure and chemical stability of the hollow-skeleton SiC foam. This research advances the knowledge of inorganic membrane extraction methods.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Xiaoyong Huang,Zhe Xu,Balaji Devakumar
Efficient broadband green-emitting phosphors are promising for application in high color rendering white light-emitting diodes (LEDs). In this paper, we report on the preparation, crystal structure and photoluminescence properties of a novel green-emitting Ca 2 LaHf 2 GaAl 2 O 12 :Ce 3+ (CLaHGA) garnet-type phosphor. All these CLaHGA: x Ce 3+ ( x = 4, 6, 8, 10, and 12 mol%) phosphors have been synthesized through using the conventional high-temperature solid-state reaction method. It has been found that the optical property of phosphors critically depends on Ce 3+ content, and the optimal doping concentration of Ce 3+ ions is 6 mol%. The optimal CLaHGA:6%Ce 3+ sample has a cubic structure with the space group Ia 3 ‾ d and lattice parameters of a = b = c = 12.62662 Å and V = 2013.08 Å 3 . The CLaHGA: x Ce 3+ phosphors exhibit an intense absorption band in the 300–485 nm range with a peak at 421 nm, due to the spin-allowed and parity-allowed 4f→5d transition of Ce 3+ ions. Upon 421 nm excitation, CLaHGA: x Ce 3+ phosphors give rise to bright broad green emission bands in the 435–750 wavelength region with peak ranging from 519 to 531 nm, owing to the spin-allowed and parity-allowed 5d→4f transition of Ce 3+ ions. For the optimal CLaHGA:6%Ce 3+ sample, its CIE color coordinates and internal quantum efficiency are determined to be (0.3135, 0.4851) and 40.7%, respectively. The full width at half maximum of CLaHGA:6%Ce 3+ is much larger than the commercial (Ba,Sr) 2 SiO 4 :Eu 2+ green phosphor (124 nm versus 71 nm), while its emission intensity is only about 39% of that of (Ba,Sr) 2 SiO 4 :Eu 2+ . Besides, the thermal stability of CLaHGA:6%Ce 3+ has also been studied. A white LED device is fabricated using the synthesized CLaHGA:6%Ce 3+ green phosphors, showing a bright warm-white light emission with high color rendering index of Ra = 89.7 and low correlated color temperature of 4058 K.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
DALTON TRANSACTIONS
·
2014
·Vol. 43
·期 32
·12321-12328
·
IF 4.097
Xiao-yan Kuang,Huan Liu,Wen-yong Hu,Yuan-zhi Shao
Multi-modal imaging based on multifunctional nanoparticles provides deep, non-invasive and highly sensitive imaging and is a promising alternative approach that can improve the sensitivity of early cancer diagnosis. In this study, two nanoparticles, TbPO4:Ce3+ and TbPO4:Ce3+@TbPO4:Gd3+, were synthesized via the citric-acid-mediated hydrothermal route, and then systematically characterized by means of microstructure, photoluminescence, magnetic resonance imaging (MRI), biocompatibility, and bioimaging. The results of energy dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS) line scans indicated that TbPO4:Gd3+ nanoshells about 5 nm in thickness were successfully coated on the TbPO4:Ce3+ nanocores. X-ray diffraction (XRD) and Fourier transforms of high-resolution transmission electron microscopy (TEM) images indicated that the core–shell nanocomposites had a single crystal structure. The photoluminescence of the TbPO4:Ce3+@TbPO4:Gd3+ and TbPO4:Ce3+ nanoparticles was greatly intensified by 200 times and 100 times, respectively, compared with pure TbPO4 nanoparticles. In vitro cytotoxicity tests based on the methyl thiazolyl tetrazolium (MTT) assay demonstrated that the monodispersed nanoparticles of TbPO4:Ce3+@TbPO4:Gd3+ had low toxicity. The intracellular luminescence of the nanoparticles after being internalized by HeLa cells was also observed using confocal fluorescence microscopes. MRI showed that the nanoshells of Gd-doped TbPO4 possessed a longitudinal relaxivity of 4.067 s−1 mM−1, which is comparable to that of the commercial MRI contrast Gd-TDPA. As a result, the core–shell structured TbPO4:Ce3+@TbPO4:Gd3+ nanoparticles can potentially serve as multifunctional nanoprobes for both optical biolabels and MRI contrast agents.
研究领域:
材料科学
·
医学影像
·
纳米生物学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Zhe Xu,Lina Cao,Jingming Chan,Balaji Devakumar,Xiaoyong Huang
Highly efficient broadband blue-emitting phosphors are urgently needed for full-visible-spectrum white light-emitting diodes (WLEDs). Herein, we report a new highly luminescent garnet-type Ca 2 LuHf 2 GaAl 2 O 12 :Ce 3+ (abbreviated as: CLHGAO:Ce 3+ ) blue phosphor enabling full-visible-spectrum LED lighting. These CLHGAO:Ce 3+ phosphors doped with different Ce 3+ concentrations have been prepared by using a high-temperature solid-state reaction approach, and their phase purity, crystal structure, luminescent properties, CIE color coordinates, and quantum efficiency have been systematically studied. Importantly, CLHGAO:Ce 3+ blue phosphors show a broadband excitation spectrum in the 300–450 nm spectral range peaking around 398 nm, matching well with the emission wavelengths of commercial near-ultraviolet LED chips (380–420 nm). Upon 398 nm excitation, the optimal CLHGAO:2%Ce 3+ phosphor sample generates a bright broad blue emission band (emission peak: 472 nm; bandwidth: 84 nm) with high internal quantum efficiency of 79.2% and external quantum efficiency of 55.3%. Notably, the emission intensity of CLHGAO:2%Ce 3+ phosphor is about 1.87 times higher compared to the commercial BaMgAl 10 O 17 :Eu 2+ blue phosphor (emission peak: 451 nm; bandwidth: 53 nm). Finally, a white LED device is fabricated with a 395 nm near-UV LED chip with CLHGAO:2%Ce 3+ blue phosphor and commercial (Ba,Sr) 2 SiO 4 :Eu 2+ green phosphor as well as commercial CaAlSiN 3 :Eu 2+ red phosphor, and the device demonstrates bright warm-white emission with an ultrahigh color rendering index (Ra = 95.1, R9 = 97.8, R12 = 88.4) and low correlated color temperature of 3540 K. These results show that as-developed blue-emitting CLHGAO:Ce 3+ garnet phosphors with superior photoluminescence properties can potentially be used in phosphor-converted full-visible-spectrum WLEDs.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry C
·
2023
·Vol. 11
·期 27
·9291-9299
·
IF 6.4
Yining Wang,Mengmeng Shang,Yixin Sun,Minliang Deng,Xiaole Xing,Peipei Dang,Jun Lin
With the increasing demand for the application of near-infrared (NIR) spectroscopy in security, agriculture, medical and other fields, people have been seeking efficient and intelligent NIR light sources. Herein, Cr3+ doped Ca3Sc2Ge3O12 (CSGG) broadband NIR phosphors are successfully synthesized. Under excitation of 480 nm, the emission peak of CSGG:Cr3+ is located at 785 nm, and the full width at half maximum (FWHM) is 106 nm. Low photoluminescence spectra (7 K and 77 K) support the broadband NIR emission coming from two Cr3+ luminescence centers occupying ScO6 and CaO8 sites, respectively. CSGG:Cr3+ exhibits excellent thermal stability (97% at 100 °C) and low internal quantum efficiency (IQE = 22%). The introduction of Ce3+ leads to the enhancement of IQE from 22% to 61% due to the following two reasons: the energy transfer from Ce3+ to Cr3+ and the lattice distortion which improves the parity forbidden transition of Cr3+. The mechanism of excellent luminescence thermal stability is revealed from the following perspectives: thermal activation energy, the Huang–Rhys factor and the thermal ionization effect. Benefiting from the excellent performance of CSGG:Cr3+,Ce3+ NIR phosphors, the combination with blue light chips demonstrates their potential applications in night vision security, biological imaging, and nondestructive testing.
研究领域:
材料科学
·
光学
·
生物医学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF LUMINESCENCE
·
2019
·
IF 2.961
Yang Liu,Mingfu Zhang,Lijun Xu,Wei Xia
Transparent Ce 3+ :YAG ceramics have great potentials in WLEDs due to their ultra-high thermal endurance property and thermal stability of luminescence. However, it is still a challenging issue to enhance their light extraction ability. In the study, the transparent Ce 3+ :YAG ceramics were fabricated using the uniform Ce:Y 2 O 3 submicron spheres by a solid-state reactive sintering method under vacuum without any sintering additives. The content of the residual pores and grain boundaries, which acted as the “light-scattering centres” to improve the absorption of blue light, were adjusted by changing sintering temperature . The luminous efficacy of the WLED with the sample sintered at 1700 °C was as high as 104.6 lm/W, due to the appropriate quantity of the “light-scattering centres”. The microstructures, transmittance , excitation and emission spectra , luminous characteristics of the samples were studied. The results showed that the preparation progress could significantly enhance the luminous efficacy in the WLED with transparent ceramics.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）