JOURNAL OF LUMINESCENCE
·
2014
·
IF 2.367
Jiansheng Huo,Jiadan Zhu,Shunhua Wu,Haijie Zhang,Qianming Wang
Red emissive phosphors of YTa 1− x Nb x O 4 :Eu 3+ ( x =0–1) have been successfully synthesized by a molten salt method. Powder characteristics were studied by X-ray diffraction, scanning electron microscopy and photoluminescence spectroscopy. The effects of Nb concentration ( x ), flux nature and firing temperature on photoluminescence behavior of YTa 1− x Nb x O 4 :Eu 3+ were extensively investigated. The results showed that the photoluminescence spectra of the samples exhibited strong red emissions (615 nm) upon the ultraviolet excitation and the emission intensities strongly dependent on the host-lattice composition and particle morphology .
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
OPTICAL MATERIALS
·
2019
·
IF 2.687
Gongcheng Xing,Mengxuan Tao,Zhiyu Gao,Shuoting Chen,Song Wang,Guogang Li
In this work, two component substitution types of Si 4+ →[Cs + -Al 3+ ] and [Mg 2+ -Mg 2+ ]→[Cs + -Al 3+ ] were successfully designed in Eu 2+ -doped CsAlSi 2 O 6 pollucite phosphors. The photoluminescence color can be controllably tuned from cyan (513 nm) to blue (437 nm), and full width at half maximum (FWHM) can be adjusted in the region of 79–169 nm. Besides, the thermal stability is obviously improved, where PL intensity at 200 °C increases from 59% (CsAlSi 2 O 6 :5%Eu 2+ ) of the original intensity to 96% [(CsAl) 0.6 Mg 0.8 Si 2 O 6 :5%Eu 2+ ] and 86% [(CsAl) 0.9 Si 2.1 O 6 :5%Eu 2+ ], respectively. The corresponding mechanisms of spectral adjustment and thermal stability enhancement were investigated. The proposed strategies can play a key role in exploiting novel and efficient phosphors for high-power w-LEDs lighting.
研究领域:
材料科学
·
光学工程
✓ 已验证
DOI
高影响因子
INORGANIC CHEMISTRY
·
2019
·
IF 4.85
Zhizhen Wang,Zhen Song,Lixin Ning,Zhiguo Xia,Quanlin Liu
The Sr3SiO5:Eu2+ phosphor has attracted considerable attention for applications in white LEDs owing to its highly efficient yellow emission under violet-blue excitation. We report herein an enhancement of yellow persistent luminescence in Sr3SiO5:Eu2+ through Ge incorporation. The strongest persistent luminescence intensity is observed for Sr3(Si1–xGex)O5:Eu2+ with x = 0.005 with a peak emission wavelength at ∼580 nm and a persistent time of ∼7000 s at the 0.32 mcd/m2 threshold value after UV radiation. A combination of thermoluminescence measurements and density functional theory (DFT) calculations reveals that the afterglow enhancement is due to a significant increase in the number of oxygen vacancies that act as electron trapping centers with appropriate trap depths. This investigation is anticipated to encourage more exploration of GeSi substitution to design and improve Si-containing persistent phosphors with superior functionalities.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2014
·
IF 4.058
Jiansheng Huo,Yuhui Zheng,Qianming Wang
Novel red-emitting Eu 3+ -activated La 2 − x Gd x (MoO 4 ) 3 − y (WO 4 ) y phosphors with well-defined one-dimensional nanostructures were synthesized via a supersonic microwave co-assistance (SMC) method for the first time at very low temperature (60 °C). Scanning electron microscopy studies substantiated that these phosphors are very uniform. The crystal structure and luminescent properties were characterized by powder X-ray diffraction patterns (XRD) and photoluminescence measurements (PL) respectively. An intense red emission at 615 nm ( 5 D 0 → 7 F 2 ) was detected under the excitation at 280 nm. The PL properties of La 2 − x Gd x (MoO 4 ) 3 − y (WO 4 ) y : Eu 3+ with different ratio of La/Gd or MoO 4 /WO 4 have also been investigated in detail. Furthermore, the optimized phosphor was embedded into the poly-hydroxyethylmethacrylate(HEMA) gel and the corresponding luminescent gel was achieved.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
CHEMISTRY OF MATERIALS
·
2023
·
IF 8.6
Yu Chen,Zhiyu Yang,Jiance Jin,Jianwei Qiao,Yuzhen Wang,Maxim S. Molokeev,Hendrik C. Swart,Zhiguo Xia
Exploring oxide-based red-emitting phosphors is essential for improving the color rendering index (Ra) and reducing the correlated color temperature (CCT) of white-light-emitting diode (LED) lighting sources. Especially, it is challenging to design Eu2+ red emission in inorganic solids. Here, the Eu2+-activated oxide phosphor Sr2LaGaO5:Eu2+ was synthesized with red emission peaking at 618 nm under 450 nm excitation. The crystal structure and spectral analysis indicate that Eu2+ tends to occupy [Sr1/LaO8] polyhedrons with a smaller coordination number, resulting in a large crystal field splitting at the 5d level and realizing the broadband 4f–5d red emission. When Sr is substituted by Ba atoms, density functional theory calculations verify that Ba tends to enter [Sr2O10] with a large coordination number, further giving rise to the lattice distortion and a giant spectral redshift (618–800 nm). The white LED device fabricated by mixing red Sr1.8Ba0.2GaO5:Eu2+ and green Lu3Al5O12:Ce3+ phosphors exhibits a high color rendering index (Ra = 92.1) and a low color-dependent temperature (CCT = 4570 K). This study will give guidance for exploring new Eu2+ activated oxide-based red phosphors as well as achieving tunable emission through cations’ substitution.
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
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Lei Zhang,Xuefeng Zhang,Chaoyong Zhao,Xuan Xiao
Eu 3+ -activated Sr 3 −x Ca x La(VO 4 ) 3 phosphors were fabricated via citric-acid-assisted sol combustion. Characterization of the Sr 3 −x Ca x La(VO 4 ) 3 :Eu 3+ samples with different concentrations of Ca 2+ revealed a hexagonal crystal structure belonging to the R -3 m space group. The amount of Ca 2+ added ( x ) was controlled within 0 ≤ x ≤ 2 to yield high-purity phosphors. Scanning electron microscopy results showed that an increase in Ca 2+ concentration resulted in a decrease in the particle size of Sr 3 −x Ca x La(VO 4 ) 3 :Eu 3+ , with the shape gradually changing from nearly equiaxed to lath-shaped. The Sr 2 CaLa(VO 4 ) 3 :Eu 3+ phosphor (denoted as SCLVO:Eu 3+ ) exhibited the strongest photoluminescence (PL) intensity at 618 nm among the samples under excitation of 394-nm near-UV (NUV) light. The study of Eu 3+ doping concentration confirmed that Eu 3+ could enter the lattice of the SCLVO matrix without altering its crystal structure. SCLVO:Eu 3+ was found to strongly absorb 394 nm NUV light and 464 nm blue light. The optimal concentration of the Eu 3+ dopant in the SCLVO host was 0.11, which resulted in the phosphor achieving an excellent PL intensity and a color purity of 98.68%. Tunable luminescence from the orange area (0.5280, 0.4522) of Commission Internationale de l'éclairage (CIE) to the red area (0.6313, 0.3650) was achieved by adjusting the concentration of Eu 3+ . Under 394 nm excitation, SCLVO:0.11Eu 3+ phosphor has a quantum yield (QY) of 28.2% and excellent thermal stability with 0.383 eV activation energy . Consequently, White-light-emitting diode (WLED) based on SCLVO:0.11Eu 3+ phosphor yielded a high color rendering index (CRI), low correlated color temperature (CCT), and CIE coordinates of 91.8, 5196 K, and (0.3407, 0.3612), respectively, under the 20 mA driven current. These results indicated the tremendous potential of SCLVO:0.11Eu 3+ phosphors for application in WLEDs excited by NUV or blue light.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
INORGANIC CHEMISTRY
·
2018
·
IF 4.7
Lizhu He,Zhen Song,Xionghui Jia,Zhiguo Xia,Quanlin Liu
T-phase (Ba,Ca)2SiO4:Eu2+, showing excellent luminescent thermal stability, has a positionally disordered structure with the splitting of five atom sites, but until now the reason has remained unclear. Herein, we investigate the coordination environments of each cation site in detail to understand the origins of the atom site splitting. We find that the three cation sites in the split-atom-site model are optimally bonded with ligand O atoms compared to the unsplit-atom-site model. This atom site splitting results in larger room and smaller room for each splitting cation site, which just accommodates larger Ba2+ ions and smaller Ca2+ ions, respectively, leading to more rigid structure. Based on the X-ray diffraction data refinement, the boundary of the T-phase for (Ba1–xCax)2SiO4 is redetermined. The Eu2+-doped T-phase (Ba,Ca)2SiO4 phosphors show excellent luminescent thermal stability, which can be attributed to optimal bonding and more rigid structure with atom site splitting. These results indicate that T-phase (Ba,Ca)2SiO4:Eu2+ phosphors have promise for practical applications.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2021
·Vol. 32
·期 1
·2103927
·
IF 18.808
Zhiyu Yang,Yifei Zhao,Yayun Zhou,Jianwei Qiao,Yu-Chun Chuang,Maxim S. Molokeev,Zhiguo Xia
Near-infrared (NIR) light-emitting diodes (LEDs) light sources are desirable in photonic, optoelectronic, and biological applications. However, developing broadband red and NIR-emitting phosphors with good thermal stability is always a challenge. Herein, the synthesis of Eu 2+ -activated SrY 2 O 4 red phosphor with high photoluminescence quantum efficiency and broad emission band ranging from 540 to 770 nm and peaking at 620 nm under 450 nm excitation is designed. Sr/Ba substitution in SrY 2 O 4 :Eu 2+ has been further utilized to achieve tunable emission by modifying the local environment, which facilitates the giant red-shifted emission from 620 to 773 nm while maintaining the outstanding thermal stability of SrY 2 O 4 :Eu 2+ . The NIR emission is attributed to the enhanced Stokes shift and crystal field strength originated from the local structural distortions of [Y1/Eu1O 6 ] and [Y2/Eu2O 6 ]. The investigation in charge distribution around Y/Eu provides additional insight into increasing covalency to tune the emission toward the NIR region. As-fabricated NIR phosphor-converted LEDs demonstration shows its potential in night-vision technologies. This study reveals the NIR luminescence mechanism of Eu 2+ in oxide-based hosts and provides a design principle for exploiting Eu 2+ -doped NIR phosphors with good thermal stability.
研究领域:
材料科学
·
光学工程
·
光电子学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Qi Sun,Shaoying Wang,Balaji Devakumar,Liangling Sun,Jia Liang,Thangavel Sakthivel,Sanjay J. Dhoble,Xiaoyong Huang
A series of novel high-brightness double perovskite tantalate Eu 3+ -activated Ca 2 LuTaO 6 (CLT) red-emitting phosphors with high thermal stability were successfully synthesized by a high-temperature solid-state method. X-ray diffraction (XRD), emission and excitation spectra, decay curves, temperature-dependent photoluminescence spectra, CIE chromaticity coordinates, as well as internal quantum efficiency (IQE) were used to analyze these phosphor samples. Under 396 nm excitation, the CLT:Eu 3+ phosphors gave brilliant red emission peaking around 616 nm due to the 5 D 0 → 7 F 2 transition of Eu 3+ ions. The optimal Eu 3+ doping concentration was 40 mol%, and moreover, the critical distance ( R c ) and θ were 8.55 Å and 5.01, respectively. Thus, the dipole-dipole interaction may be responsible for the energy transfer mechanism of Eu 3+ activators in the CLT:Eu 3+ phosphors. In addition, the color purity of CLT:0.4Eu 3+ sample was calculated to be 95.8% and its IQE was found to be as high as 74%. Impressively, the integrated emission intensity of CLT:0.4Eu 3+ was about 3.79 times higher than that of commercial Y 2 O 3 :Eu 3+ red phosphors under 396 nm excitation. More importantly, the CLT:0.4Eu 3+ sample exhibited excellent thermal stability. Therefore, these superior luminescence properties of CLT:Eu 3+ phosphors demonstrated their potential applications in white light-emitting diodes (WLEDs) as red color converters.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
Light-Science & Applications
·
2024
·Vol. 13
·期 1
·1-11
·
IF 20.6
Zhao Ming,Ge Yeping,Li Yurong,Song Xiaoyan,Xia Zhiguo,Zhang Xinping
Highly efficient inorganic phosphors are desirable for lighting-emitting diode light sources, and increasing the doping concentration of activators is a common approach for enhancing the photoluminescence quantum yield (PLQY). However, the constraint of concentration quenching poses a great challenge for improving the PLQY. Herein, we propose a fundamental design principle by separating activators and prolonging their distance in Eu 2+ -activated Rb 3 Y(PO 4 ) 2 phosphors to inhibit concentration quenching, in which different quenching rates are controlled by the Eu distribution at various crystallographic sites. The blue-violet-emitting Rb 3 Y(PO 4 ) 2 : x Eu ( x = 0.1%–15%) phosphors, with the occupation of Rb1, Rb2 and Y sites by Eu 2+ , exhibit rapid luminescence quenching with optimum external PLQY of 10% due to multi-channel energy migration. Interestingly, as the Eu concentration increases above 20%, Eu 2+ prefer to occupy the Rb1 and Y sites with separated polyhedra and large interionic distances, resulting in green emission with suppressed concentration quenching, achieving an improved external PLQY of 41%. Our study provides a unique design perspective for elevating the efficiency of Eu 2+ -activated phosphors toward high-performance inorganic luminescent materials for full-spectrum lighting.
研究领域:
材料科学
·
光学工程
·
无机化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）