scholarly journals New Multicolor Tungstate-Molybdate Microphosphors as an Alternative to LED Components

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6608
Author(s):  
Justyna Czajka ◽  
Agata Szczeszak ◽  
Nina Kaczorowska ◽  
Stefan Lis
Keyword(s):  
Color Change ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Luminescence Spectroscopy ◽  
Solid State Method ◽  
Light Emitting ◽  
Tetragonal Crystal ◽  
Emission Color ◽  
The Matrix ◽  
Cie Chromaticity

Due to the ongoing need to create phosphors with the appropriate emission color for the production of light emitting diodes, we decided to synthesize a series of multicolour microphosphors with tunable visible emissions, depending on the composition of dopant ions. In this work, we investigated the structure, morphology, and luminescent properties of new molybdate–tungstate phosphors co-doped with Tb3+ and Eu3+ ions. The conventional high temperature solid state method was used to prepare a series of CaMoyW1−yO4:Eu3+x/Tb3+1−x materials. In order to obtain phosphors with the most promising luminescent properties, the experiment was planned by taking into account the different composition of the matrix and the concentration of the particular dopant ions (Eu3+x/Tb3+1−x, x = 0.001, 0.003, 0.005, 0.007, 0.009). As a result, luminescent materials were obtained with a pure tetragonal crystal structure, the space group of I41/a, confirmed by X-ray diffraction (XRD). The size and shape of the particles obtained from the materials were analyzed based on scanning electron microscopy images. Luminescence spectroscopy (excitation and emission spectra, decay lifetimes) was utilized to characterize the luminescence properties of the as-prepared phosphors. The color change of the emission from green-yellow to orange-red was confirmed using the 1931 Comission Internationale de l’Eclairage (CIE) chromaticity coordinates and color correlated temperature (CCT).

LUMINESCENT PROPERTIES OF Sr3B2O6: Eu2+ YELLOW-EMITTING PHOSPHOR FOR WHITE LIGHT-EMITTING DIODES

2013 ◽  
Vol 06 (01) ◽  
pp. 1350009 ◽  
Author(s):  
QUAN-SHENG LIU ◽  
TIAN CUI ◽  
XI-YAN ZHANG ◽  
YUE SONG
Keyword(s):  
Wide Band ◽  
Luminescent Properties ◽  
Color Temperature ◽  
Broad Emission Band ◽  
Band Spectrum ◽  
White Led ◽  
Solid State Method ◽  
Light Emitting ◽  
Yellow Phosphor ◽  
Cie Chromaticity

Eu2+ doped Sr3B2O6 yellow phosphor for warm white LED was synthesized by high temperature solid-state method. The structure and optical properties of Sr3B2O6 : Eu2+ were studied. Results indicate that Sr3B2O6 : Eu2+ has a rhombohedral crystalline structure. The excitation spectrum of phosphor is a wide-band spectrum mainly peaking at 469 nm, which is suitable for GaN -based blue light LED excitation. The luminescent spectrum of phosphor exhibits a broad emission band centered at 566 nm, corresponding to the typical 4f65d1–4f7 transition of Eu2+ . Guass fitting shows the main emission peak is at 575 nm, which is identical with the dominant wavelength of the yellow phosphor. The CIE chromaticity coordinate of white LED is (x = 0.389, y = 0.419). The LED reveals warm tone and the relevant color temperature of that is 4044 K. The luminescent efficiency of White LED reaches 18l m/W, which is higher than reported.

scholarly journals Synthesis and Luminescent Properties of Eu3+/Tb3+ Rare Earth Ions Doped Li2SrSiO4 Phosphors

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Kaitao Yu ◽  
Lifang Wei ◽  
Jiaqi Shen
Keyword(s):  
Charge Transfer ◽  
Charge Transfer Band ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Rare Earth Ions ◽  
Luminescent Materials ◽  
Excitation Spectra ◽  
Solid State Method ◽  
X Ray ◽  
Uv Visible

The series of luminescent materials of Eu3 +, Tb3 + doped Li2SrSiO4 were synthesized by a high-temperature solid-state method. The phase purity of the samples was measured by X-ray powder diffraction (XRD). The luminescent properties of the samples were studied by UV-visible excitation spectra and emission spectra The It is found that the strong absorption of Eu3 + doped Li2-xSr1-xEuxSiO4 is from the 250 ~ 290 nm charge transfer band of Eu3 + and the 7F0 → 5L6 absorption transition of 393 nm. The strongest emission of the emission spectra at 393 nm is 614 nm and 701 nm, respectively, from the 5D0 → 7F2 and 5D0 → 7F4 transitions of Eu3 +. Tb3 + doped sample Li2-xSr1-xTb xSiO4 excitation spectrum is mainly composed of Tb3 + ion fd transition and charge transfer band composed of broadband, the strongest absorption at 269 nm, the emission of the main emission of 5D4 → 7F5 transition (542 nm).

Photo and Electroluminescent Properties of a Porphyrin-Poly(p-Phenylene Vinylene) Derivative

1999 ◽  
Vol 598 ◽  
Author(s):  
J. Morgado ◽  
R. Iqbal ◽  
G. Yahioglu ◽  
L. R. Milgrom ◽  
S. C. Moratti ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Solid State ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Phenylene Vinylene ◽  
Efficient Energy Transfer ◽  
Light Emitting ◽  
Efficient Energy ◽  
Small Absorption ◽  
Pl Emission

ABSTRACTThe solid state luminescent properties of new statistical copolymers of 2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene and a porphyrin-substituted phenylene vinylene are reported. The photoluminescence, PL, emission shows an efficient energy transfer to the porphyrin, in spite of the small absorption coefficient of the porphyrin in the wavelength range of the poly [2-methoxy-5-(2'- ethylhexyloxy)-1,4-phenylene vinylene], MEH-PPV, emission. At a porphyrin content of 0.25%, by weight, the emission is already dominated by the porphyrin. The PL efficiency of these copolymers is significantly reduced from the value of 13% for MEH-PPV down to 3% for the copolymer with 10.84% of porphyrin. Efficient energy transfer is also observed in the emission spectra of light-emitting diodes.

Luminescent Properties and Thermometry of CaWO4:Nd3+ in Near Infrared Region

2017 ◽  
Vol 893 ◽  
pp. 156-160
Author(s):  
Rong Xue Wang ◽  
Xiao Bing Luo
Keyword(s):  
Near Infrared ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Infrared Region ◽  
Excitation Spectra ◽  
Efficient Energy Transfer ◽  
Fluorescent Intensity ◽  
Sensor Device ◽  
The Matrix ◽  
Increasing Temperature

CaWO4: xNd3+ (x = 0.005, 0.008, 0.01, 0.015, 0.02, 0.025 0.03) powders have been synthesized by high-temperature solid state reaction. The results of the XRD indicate that Nd3+ ions have entered into the crystal lattice in all compounds successfully. The reflectance spectra show that the matrix has strong absorption. The emission spectra, excitation spectra and different lifetimes between CaWO4 and CaWO4: 0.5% Nd3+ indicate that efficient energy transfer occurs from WO42- cluster to Nd3+ ions. On the basis of the above work, the dependence of fluorescent spectra on temperature was studied. It turned out that, not only the excitation spectra appeared red shift with increasing temperature, but also the dependence of the near infrared fluorescent intensity on temperature is fitting with a linear function. It might be served as a promising phosphor for temperature sensor device.

Synthesis and Luminescent Properties of Mn2+-Doped Zinc Silicate Phosphors by Sol-Gel Method

2010 ◽  
Vol 434-435 ◽  
pp. 214-216 ◽  
Author(s):  
Ji Ming Zhang ◽  
Dong Lin Zhao ◽  
Zeng Min Shen
Keyword(s):  
Sol Gel ◽  
Green Light ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Nano Particles ◽  
Light Emitting ◽  
Gel Method ◽  
Sol Gel Method ◽  
Structural Details ◽  
Xrd Patterns

Abstract. Green light emitting Mn2+-doped Zn2SiO4 (Zn2SiO4:Mn2+) phosphor nano-particles were synthesized by sol-gel method combined with a furnace firing from the sol-gel solution made with ZnO, MnCO3 and tetraethoxysilan. The influences of annealing temperatures on the microstructures and photoluminescent properties of the Zn2SiO4:Mn2+ phosphors were investigated. The structural details of the phosphors were examined through XRD and SEM. The photoluminescent properties of the Zn2SiO4:Mn2+ phosphors were characterized by excitation and emission spectra. The results indicate that the XRD patterns of the Zn2SiO4:Mn2+ phosphors exhibit a willemite structure (-Zn2SiO4). Green photoluminescence whose emission peak is located at 525 nm were observed from the synthesized phosphor particles under UV excitation. The photoluminescent mechanisms of the Zn2SiO4:Mn2+ phosphors were discussed.

Color Tunability of Blue Phosphors by Changing Cations for Near-UV InGaN-Based Light-Emitting Diode

2014 ◽  
Vol 986-987 ◽  
pp. 156-159
Author(s):  
Yi Wen Zhu ◽  
Fen Fen Hu ◽  
Mei Li Zhou ◽  
Ping Chen ◽  
Zheng Liang Wang
Keyword(s):  
Uv Light ◽  
Light Emitting Diode ◽  
Blue Emission ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Blue Shift ◽  
Ionic Radii ◽  
Light Emitting ◽  
Triclinic Structure ◽  
The Difference

The serials of blue phosphors, CaAl2Si2O8: Eu2+ doped with different content Sr2+ and Mg2+ ions, were prepared by solid-state reaction at high temperature. And their structure and photo-luminescent properties were investigated. In Ca0.96-ySryAl2Si2O8: 0.04Eu2+ (y = 0.10, 0.30, 0.50, 0.70, 0.90) system, for y ≦ 0.03, all the compositions crystallize in triclinic structure of CaAl2Si2O8, and on further increase of y, the system undergoes a compositionally induced phase transition from triclinic to monoclinic structure. For Ca0.96-yMgyAl2Si2O8: 0.04Eu2+ (y = 0.10, 0.30, 0.50, 0.70, 0.90) system, for z ≦ 0.03, all the compositions are of triclinic structure of CaAl2Si2O8. With the further increase of z, other phase appears. The emission spectra of these phosphors show blue shift with the introduction of Sr2+ ions, and red shift with Mg2+ ions. The reason may be due to the difference ionic radii of Mg2+, Ca2+, Sr2+. These phosphors show excellent blue emission and broad excitation band in near-UV (ultraviolet) range. They may be potential phosphors for near-UV light-emitting diodes (LEDs).

The self-reduction synthesis and luminescent properties of Eu2+-Eu3+ activated BaZr0.2Si2O5.4 phosphors with white light emission for white light-emitting diodes

2018 ◽  
Vol 32 (04) ◽  
pp. 1850047 ◽  
Author(s):  
Jianlin Zhong ◽  
Lixin Yu ◽  
Songchu Li ◽  
Xiaoqin Man ◽  
Wei Sun
Keyword(s):  
White Light ◽  
Light Emission ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
White Light Emission ◽  
Photoluminescence Properties ◽  
X Ray Diffraction ◽  
Light Emitting ◽  
Broadband Emission ◽  
White Light Emitting Diodes

The BaZr[Formula: see text]Si2O[Formula: see text]: Eu[Formula: see text]/Eu[Formula: see text] phosphors were prepared with different concentrations of Eu2O3 by a self-reduction method under air condition. The X-ray diffraction and the photoluminescence properties of the prepared samples were analyzed. The emission spectra consisting of a broadband emission from the 4f[Formula: see text]5d transitions of Eu[Formula: see text] and sharp emissions from 5D0-7F[Formula: see text] (J = 0, 1, 2, 3, 4) transitions of Eu[Formula: see text] are observed. The different luminescent colors can be obtained and modulated by doping different concentrations of Eu2O3 and the white light emission can be observed as the concentration of europium is 6%.

scholarly journals Crystal Structure and Luminescence Properties of a Thermally Stable Single-Phase White Emitting Phosphor CaSr2(PO4)2: Dy3+, Li+

2021 ◽  
Author(s):  
Qingfeng Guo ◽  
Yuying Chen ◽  
Qiang Hao ◽  
Stefan Lis ◽  
Haikun Liu ◽  
...  
Keyword(s):  
White Light ◽  
Single Phase ◽  
Emission Spectra ◽  
Luminescence Properties ◽  
Solid State Method ◽  
Excellent Thermal Stability ◽  
Light Emitting ◽  
Diffraction Patterns ◽  
White Light Emitting Diodes ◽  
White Luminescence

Abstract Single-phase CaSr2(PO4)2:Dy3+,Li+ phosphors were prepared using the high-temperature solid-state method in the air. To characterize the luminescence properties of the synthesized phosphors, Powder X-ray diffraction patterns (XRD), scanning electron microscopy images (SEM), photoluminescence spectra, and concentration-dependent emission spectra were measured to characterize the luminescence properties of the synthesized phosphors. The results showed that the CaSr2(PO4)2:Dy3+,Li+ phosphors exhibited white luminescence, and the emission spectra of the phosphors consisted of two sharp peaks at ≈486 and ≈578 nm (the most intense one). The optimum concentration of Dy3+ doping was determined to 0.06 mol.%. On the basis of the Dexter's theory, the mechanism of energy transfer between the Dy3+ ions was determined to dipole–dipole interactions. The results of the temperature-dependent luminescence confirmed that the as-prepared phosphors are proved to be promising UV-convertible material capable of white light emitting in UV-LEDs due to its excellent thermal stability and luminescence properties. Luminescence intensity and decay time of the CaSr2(PO4)2:Dy3+,Li+ phosphors were improved remarkably with the addition of charge compensators (Li+ ions), which would promote their applications in white light-emitting diodes based on the near-UV chip.

Emission Color Variation of Sr3SiO5:Ce3+, Li+ Phosphor for Near-UV Light-Emitting Diodes by Co-Doping with Mg2+ and Ba2+

2013 ◽  
Vol 690-693 ◽  
pp. 555-558 ◽  
Author(s):  
Ping Ping Zhu ◽  
Tong Wen Huang ◽  
Xiao Jun Wang ◽  
Hui Li Li ◽  
Zhuo Sun
Keyword(s):  
Thermal Stability ◽  
Uv Light ◽  
Color Variation ◽  
Spectral Variation ◽  
Solid State Method ◽  
Light Emitting ◽  
Co Doping ◽  
Yellow Color ◽  
Emission Color ◽  
Composition Structure

This paper reports the spectral variation of Sr3SiO5: Ce3+, Li+ phosphor. It was synthesized by the conventional solid state method. The effects of calcining temperature and codoption of Mg2+ and Ba2+ on phase composition, structure, photoluminescence and thermal stability were firstly investigated in detail. Under the near-UV excitation of 415 nm, Sr3SiO5: Ce3+, Li+ emits a bright greenish-yellow color centered at 532nm, which originates from 5d to 4f (2F7/2 and 2F5/2) transition of Ce3+. The PL spectra show the different emission color variation with substituting Sr2+ cations with smaller Mg2+ or larger Ba2+, which makes it be applied as a color-tunable phosphor for LED based on near-UV chip/phosphor technology. Simultaneously, the thermal stability of (Sr,Ba)3SiO5: Ce3+, Li+ phosphor is improved markedly.

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