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1.
A series of Sr2ZnWO6 phosphors co‐doped with Eu3+, Bi3+ and Li+ were prepared using the Pechini method. The samples were tested using X‐ray diffraction and luminescence spectroscopy. The results show that the samples can be effectively excited by near‐ultraviolet (UV) and UV light. The introduction of Bi3+ and Li+ significantly enhances the fluorescence emission of Sr2ZnWO6:Eu3+ and changes the light emitted by the phosphors from bluish‐green to white. When excited at 371 nm, Sr2–x–zZn1–yWO6:xEu3+,yBi3+,zLi+ (x = 0.05, y = 0.05, z = 0.05, 0.1 and 0.15) samples emit high‐performance white light. Intense red–orange emission is also observed when excited by UV light. The obtained phosphor is a potential white‐emitting phosphor that could meet the needs of excitation sources with near‐UV chips. In addition, this phosphor might have promising application as a red–orange emitting phosphor for white light‐emitting diodes based on UV light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

2.
A series of phosphors KAl1‐xPO4Cl:Eux3+ (0.1 ≤ x ≤ 1.0) was synthesized using a facile combustion method using urea as a fuel and their structural, morphological and photoluminescence properties were investigated. It was found that the particle size was in the range of 1–2 µm with an irregular shape. The f–f transitions of Eu3+ in the host lattice were assigned and discussed. The excitation and emission spectra indicated that this phosphor can be efficiently excited by ultraviolet (395 nm), and exhibit reddish orange emission corresponding to the 5D07FJ (J = 0, 1, 2) transitions of Eu3+. The impact of the Eu3+ concentration on the relative emission intensity was investigated, and the best doping concentration is 0.5. The present study suggests that the KAl0.5PO4Cl: Eu0.53+ phosphor is a strong candidate as a red component for phosphor‐ converted white light‐emitting diodes (LEDs). Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

3.
In this study, Li6Y1–xEux(BO3)3 phosphor was successfully synthesized using a modified solid‐state diffusion method. The Eu3+ ion concentration was varied at 0.05, 0.1, 0.2, 0.5 and 1 mol%. The phosphor was characterized for phase purity, morphology, luminescent properties and molecular transmission at room temperature. The XRD pattern suggests a result closely matching the standard JCPDS file (#80‐0843). The emission and excitation spectra were followed to discover the luminescence traits. The excitation spectra indicate that the current phosphor can be efficiently excited at 395 nm and at 466 nm (blue light) to give emission at 595 and 614 nm due to the 5D07Fj transition of Eu3+ ions. Concentration quenching was observed at 0.5 mol% Eu3+ in the Li6Y1–xEux(BO3)3 host lattice. Strong red emission with CIE chromaticity coordinates of phosphor is x = 0.63 and y = 0.36 achieved with dominant red emission at 614 nm the 5D07 F2 electric dipole transition of Eu3+ ions. The novel Li6Y1–xEux(BO3)3 phosphor may be a suitable red‐emitting component for solid‐state lighting using double‐excited wavelengths, i.e. near‐UV at 395 nm and blue light at 466 nm. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

4.
In this work, we studied the luminescence properties of Tb3+‐doped MgPbAl10O17 green phosphor. To understand the excitation mechanism and corresponding emission of the prepared phosphor, its structural, morphological and photoluminescence properties were investigated. In general, for green emission, Tb3 is used as an activator and the obtained excitation and emission spectra indicated that this phosphor can be effectively excited by a wavelength of 380 nm, and exhibits bright green emission centered at 545 nm corresponding to the f → f transition of trivalent terbium ions. The chromaticity coordinates were (Cx = 0.263, Cy = 0.723). The impact of Tb3+ concentration on the relative emission intensity was investigated, and the best doping concentration was found to be 2 mol%. This study suggests that Tb3+‐doped MgPbAl10O17 phosphor is a strong candidate for a green component in phosphor‐converted white light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

5.
A series of single‐phase full‐color emitting Li2Sr1−x−ySiO4:xDy3+,yEu3+ phosphors were synthesized by solid‐state reaction and characterized by X‐ray diffraction and photoluminescence analyses. The samples showed emission peaks at 488 nm (blue), 572 nm (yellow), 592 nm (orange) and 617 nm (red) under 393 nm excitation. The photoluminescence excitation spectra, comprising the Eu–O charge transfer band and 4f–4f transition bands of Dy3+ and Eu3+, range from 200 to 500 nm. The Commission Internationale de I'Eclairage chromaticity coordinates for Li2Sr0.98−xSiO4:0.02Dy3+,xEu3+ phosphors were simulated. By manipulating Eu3+ and Dy3+ concentrations, the color points of Li2Sr1−x−ySiO4:xDy3+,yEu3+ were tuned from the greenish‐white region to white light and eventually to reddish‐white region, demonstrating that a tunable white light can be obtained by Li2Sr1−x−ySiO4:xDy3+,yEu3+ phosphors. Li2Sr0.98−xSiO4:0.02Dy3+, xEu3+ can serve as a white‐light‐emitting phosphor for phosphor‐converted light‐emitting diode. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

6.
Zn‐doped CaTiO3:Eu3+ red phosphors for enhanced photoluminescence in white light‐emitting diodes (LEDs) were synthesized by a solid‐state method. The structure and morphology of the obtained phosphor samples were observed by X‐ray diffraction (XRD) and scanning electron microscopy (SEM), and the impact of Ca, Zn and Eu content on their photoluminescence properties was studied. The results indicated that Zn not only participates in the formation of defects in suitable lattice matrices but also has a role in flux in the transformation from ZnO to Zn2TiO4, which is beneficial for the enhancement of photoluminescence properties. Photoluminescence test data showed that the Zn‐doped phosphor is excited efficiently by near‐ultraviolet (NUV) light at wavelengths around 398 nm and emits an intense red light with a broad peak around 616 nm corresponding to the 5D07F2 transition of Eu3+. The intensity of this phosphor emission is three times stronger than that without Zn‐doping. Furthermore, this phosphor has very good thermal stability, high color purity and a low sintered temperature, all of which suggest its potential as a promising red phosphor for white LEDs. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

7.
Eu3+‐activated MAl(SO4)2Br phosphors (where M = Mg or Sr) are successfully prepared using a wet chemical reaction technique. The samples are characterized by X‐ray diffraction (XRD) and photoluminescence (PL) spectroscopies. The XRD pattern revealed that both the samples are microcrystalline in nature. PL of Eu3+‐doped SrAl(SO4)2Br and MgAl(SO4)2Br phosphors exhibited characteristic red emission coming from the 5D07F2 (616 nm) electron transition, when excited by 396 nm wavelength of light. The maximum intensity of luminescence was observed at a concentration of 1 mol% Eu3+. The intensity of the electric dipole transition at 616 nm is greater than that of the magnetic dipole transition at 594 nm. The results showed that MAl(SO4)2Br:Eu3+, (M = Mg, Sr) phosphors have potential application in near‐UV light‐emitting diodes as efficient red‐emitting phosphor. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

8.
Near‐UV excited narrow line red‐emitting phosphors, Eu3+‐activated Y2MoO6 systems, were synthesized using a simple molten salt reaction. The structure and photoluminescence characteristics were investigated using X‐ray powder diffraction, UV–Vis absorption and fluorescent spectrophotometry. The excitation spectra show strong broad‐band absorptions in the near‐UV to blue light regions which match the radiation of near‐UV light‐emitting diode chips well. Under excitation of either near‐UV or blue light, intense red emission with a main peak of 611 nm is observed, ascribed to the 5D07F2 transition of Eu3+ ions; the optimal doping concentration is 20 mol%. The chromaticity coordinates (x = 0.65, y = 0.34) of the as‐obtained phosphor are very close to the National Television Standard Committee standard values (x = 0.67, y = 0.33). All these characteristics suggest that this material is a promising red‐emitting phosphor candidate for white‐LEDs based on near‐UV LED chips. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

9.
We report the synthesis and structural characterization of Er3+,Yb3+‐doped Gd2O3 phosphor. The sample was prepared using the conventional solid‐state reaction method, which is the most suitable method for large‐scale production. The prepared phosphor sample was characterized using X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermoluminescence (TL), photoluminescence (PL) and CIE techniques. For PL studies, the excitation and emission spectra of Gd2O3 phosphor doped with Er3+ and Yb3+ were recorded. The excitation spectrum was recorded at a wavelength of 551 nm and showed an intense peak at 276 nm. The emission spectrum was recorded at 276 nm excitation and showed peaks in all blue, green and red regions, which indicate that the prepared phosphor may act as a single host for white light‐emitting diode (WLED) applications, as verified by International de I'Eclairage (CIE) techniques. From the XRD data, the calculated average crystallite size of Er3+ and Yb3+‐doped Gd2O3 phosphor is ~ 38 nm. A TL study was carried out for the phosphor using UV irradiation. The TL glow curve was recorded for UV, beta and gamma irradiations, and the kinetic parameters were also calculated. In addition, the trap parameters of the prepared phosphor were also studied using computerized glow curve deconvolution (CGCD). Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

10.
Red‐emitting Mg4Nb2O9:Eu3+ phosphor is synthesized via a solid‐state reaction method in air, and its crystal structure and luminescence are investigated. The phosphor can be excited efficiently by ~ 395 nm light, coupled well with a ~ 395 nm near‐ultraviolet chip and emits red light at ~ 613 nm with sharp spectra due to 5D07 F2 transition of the Eu3+ ion. Mg4Nb2O9:Eu3+ phosphor sintered at 1350 ºC shows Commission international de I'Eclairage (CIE) chromaticity coordinates of x = 0.6354, y = 0.3592, and is a potential red‐emitting phosphor candidate for white light‐emitting diodes (W‐LEDs) under ~ 395 nm near‐ultraviolet LED chip excitation. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

11.
Triple whitlockite‐type structure‐based red phosphors Ca8MgBi1?x(PO4)7:xEu3+ (x = 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80 and 1.00) were synthesized by a conventional solid‐state reaction route and characterized by their X‐ray crystal structures. The X‐ray diffraction (XRD) patterns, Fourier transform infrared spectra, morphologies, photoluminescence spectra, UV/Vis reflectance spectra, decay times and the International Commission on Illumination (CIE) chromaticity coordinates of Ca8MgBi1?x(PO4)7:xEu3+ were analyzed. Eu‐doped Ca8MgBi(PO4)7 phosphors exhibited strong red luminescence with peaks at 616 nm due to the 5D07 F2 electric dipole transition of Eu3+ ions after excitation at 396 nm. The UV/Vis spectra indicated that the band gap of Ca8MgBi0.30(PO4)7:0.70Eu3+ is larger than that of Ca8MgBi(PO4)7. The phosphor developed in this study has great potential as a red‐light‐emitting phosphor for UV light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

12.
This paper focuses on an optical study of a Tb3+/Bi3+‐doped and Sm3+/La3+‐ doped Ca2Al2SiO7 phosphor synthesized using combustion methods. Here, Ca2Al2SiO7:Sm3+ showed a red emission band under visible light excitation but, when it co‐doped with La3+ ions, the emission intensity was further enhanced. Ca2Al2SiO7:Tb3+ shows the characteristic green emission band under near‐ultraviolet light excitation wavelengths, co‐doping with Bi3+ ions produced enhanced photoluminescence intensity with better colour tunable properties. The phosphor exhibited better phase purity and crystallinity, confirmed by X‐ray diffraction. Binding energies of Ca(2p), Al(2p), Si(2p), O(1s) were studied using X‐ray photoelectron spectroscopy. The reported phosphor may be a promising visible light excited red phosphor for light‐emitting diodes and energy conversion devices.  相似文献   

13.
A high intensity 464 nm excitable ZnWO4:Eu3+ red‐emitting phosphor for warm white lighting applications was prepared using a solid‐state reaction method by varying the dopant Eu3+ concentration. Crystalline purity and phase identification was confirmed and revealed using powder X‐ray diffraction and Rietveld refinement analysis. The surface morphology of Zn1‐xEuxWO4 (x = 0, 0.01, 0.02, 0.03, 0.04 and 0.05) was examined using scanning electron microscopy (SEM) techniques. From SEM analysis, the ZnWO4:Eu3+ phosphor prepared at 1–3% molar Eu3+ concentrations exhibited a small pebble‐like morphology with a smooth surface. On increasing the molar concentration of Eu3+ to >3%, the pebble stone morphology disappeared and a large, smooth irregular polygon‐shaped granular‐like morphology was obtained. Of the higher mol% Eu3+, the 4% Eu3+‐doped ZnWO4 showed the best photoluminescence properties with high intensity and sharp excitation at 395 and 464 nm, followed by red emission centred at 615 nm with excellent CIE coordinates (x = 0.58 and y = 0.41) in the core red region. Elemental composition and chemical state analysis were carried out for the 4% Eu3+‐doped ZnWO4 phosphor using X‐ray photoelectron spectroscopy and energy dispersive X‐ray spectroscopy studies. Based on all the above analyses, the Eu3+‐doped ZnWO4 phosphor was found to be a very efficient red‐emitting phosphor under near‐UV light as well as under visible light excitation and could be used for white LED and field emissive displays applications.  相似文献   

14.
The red‐emitting phosphor Ca0.8Zn0.2TiO3:Pr3+ was synthesized using an ethylene glycol (EG)‐assisted hydrothermal method. The effects of additional amounts of and order of adding EG, plus hydrothermal temperature, time, and pH on the composition, morphology and optical properties of the titanate phosphors were studied. The crystalline phases of the titanate phosphors were confirmed to be constituted of a series of co‐existing CaTiO3, Zn2TiO4 and Ca2Zn4Ti16O38 compounds in various proportions that were visualized using an X‐ray diffractometer (XRD). The optical properties of the phosphors were studied using photoluminescence spectra and UV–visible spectroscopy. The results show that the impurities Zn2TiO4:Pr3+ and Ca2Zn4Ti16O38:Pr3+ significantly contributed to the enhancement of an absorption band around 380 nm. The optimum Ca0.8Zn0.2TiO3:Pr3+ phosphor consisting of appropriate amounts of CaTiO3, Ca2Zn4Ti16O38 and Zn2TiO4 in three phases was achieved by controlling the hydrothermal conditions, and the obtained red phosphor exhibited the highest red emission (1D2 → 3H4 transition of Pr3+) with an ideal chromaticity coordinate located at (x = 0.667, y = 0.332) under 380 nm excitation.  相似文献   

15.
Cerium (Ce3+)‐doped (1, 3, and 7 mol%) yttrium vanadate phosphors were prepared using a co‐precipitation technique. The structural and optical properties of the synthesized samples were studied using X‐ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), high‐resolution transmission electron microscopy (HR‐TEM), optical absorption, and photoluminescence (PL) spectroscopy techniques. The tetragonal structure and the formation of the nanosized crystallites in the YVO4:Ce phosphor were confirmed using XRD analysis. HR‐TEM morphology showed rod‐like nanoparticles of different sizes. Optical absorption spectra demonstrated strong absorption bands at 268 and 276 nm. PL spectra showed strong peaks at 546, 574, and 691 nm following excitation at 300 nm. The calculated CIE chromaticity coordinates demonstrated that YVO4:Ce could be used as a novel phosphor for the development of light‐emitting diode lamps.  相似文献   

16.
Erbium‐doped nano‐sized Gd2O3 phosphor was prepared by a solution combustion method in the presence of urea as a fuel. The phosphor was characterized by X‐ray diffractometry (XRD), Fourier transform infra‐red spectroscopy, energy dispersive X‐ray analysis (EDX) and transmission electron microscopy (TEM). The results of the XRD shows that the phosphor has a monoclinic phase, which was further confirmed by the TEM results. Particle size was calculated by the Debye–Scherrer formula. The erbium‐doped Gd2O3 nanophosphor was revealed to have good down‐conversion (DC) properties and the intensity of phosphor could be modified by annealing. The effects of annealing at 900°C on the particle size and luminescence properties were studied and compared with freshly prepared Gd2O3:Er3+ nanoparticles. The average particle sizes were calculated as 8 and 20 nm for the freshly prepared samples and samples annealed at 900°C for 1 h, respectively. The results show that both freshly prepared and annealed Gd2O3:Er3+ have monoclinic structure. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

17.
Dysprosium ion (Dy3+) activated Ba2CaZn2Si6O17 phosphors were synthesized using high temperature solid‐state reaction method. Powder X‐ray diffraction (PXRD) analysis confirmed the phase formation of the as‐prepared phosphors. Scanning electron microscopy (SEM) analysis disclosed an agglomeration of particles with an irregular morphology. Under 350 nm excitation, the emission spectrum of Dy3+ ions showed bands at 481 nm (blue), 577 nm (yellow) and 674 nm (red). The influence of the Dy3+ concentration on its emission intensity was investigated. The optimum concentration of Dy3+ ions in the Ba2CaZn2Si6O17:Dy3+ phosphors were found to be x = 0.06. The critical energy transfer distance was calculated. The fluorescence lifetime was also determined for Ba2CaZn2Si6O17:0.06Dy3+. The Commission International deI’Eclairage (CIE) chromaticity coordinates of the phosphor were calculated to be x = 0.304, y = 0.382. The activation energy for the thermal quenching was calculated to be 0.168 eV. These results indicated that the Ba2CaZn2Si6O17:Dy3+ phosphor might be a potential candidate for near ultraviolet (NUV)‐based white light‐emitting diodes.  相似文献   

18.
In order to improve the luminescent performance of silicate blue phosphors, Sr(1.5‐x)‐(1.5y)Mg0.5SiO4:xEu2+,yCe3+ phosphors were synthesized using one‐step calcination of a precursor prepared by chemical co‐precipitation. The crystal structure and luminescent properties of the phosphors were analyzed using X‐ray diffraction and fluorescence spectrophotometry, respectively. Because the activated ions (Eu2+) can occupy two different types of sites (Sr1 and Sr2), the emission spectrum of Eu2+ excited at 350 nm contains two single bands (EM1 and EM2) in the wavelength range 400–550 nm, centered at 463 nm, and the emission intensity first increases and then decreases with increasing concentrations of Eu2+ ions. Co‐doping of Ce3+ ions can greatly enhance the emission intensity of Eu2+ by transferring its excitation energy to Eu2+. Because of concentration quenching, a higher substitution concentration of Ce3+ can lead to a decrease in the intensity. Meanwhile, the quantum efficiency of the phosphor is improved after doping with Ce3+, and a blue shift phenomenon is observed in the CIE chromaticity diagram. The results indicate that Sr(1.5‐x)‐(1.5y)Mg0.5SiO4:xEu2+,yCe3+ can be used as a potential new blue phosphor for white light‐emitting diodes.  相似文献   

19.
A novel phosphor LiBaPO4 doped with rare earths Eu and Dy prepared by high temperature solid‐state reaction method is reported. The phosphors were characterized by X‐ray powder diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL). The emission and excitation spectra of these materials were measured at room temperature with a spectrofluorophotometer. The excitation spectra of LiBaPO4:Eu3+ phosphor can be efficiently excited by 394 nm, which is matched well with the emission wavelength of near‐UV light‐emitting diode (LED) chip. PL properties of Eu3+‐doped LiBaPO4 exhibited the characteristic red emission coming from 5D07 F1 (593 nm) and 5D07 F2 (617 nm) electronic transitions with color co‐ordinations of (0.680, 0.315). The results demonstrated that LiBaPO4:Eu3+ is a potential red‐emitting phosphor for near‐UV LEDs. Emission spectra of LiBaPO4:Dy3+ phosphors showed efficient blue (481 nm) and yellow (574 nm) bands, which originated from 4 F9/26H15/2 and 4 F9/26H13/2 transitions of the Dy3+ ion, respectively. The 574 nm line is more intense than the 481 nm lines, which indicates that the site Dy3+ is located with low symmetry. This article summarizes fundamentals and possible applications of optically useful inorganic phosphates with visible photoluminescence of Eu3+ and Dy3+ ions. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

20.
Ca2MgSi2O7:Eu2+,Dy3+ phosphor was prepared by the solid‐state reaction method under a weak reducing atmosphere. The obtained phosphor was characterized using X‐ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy dispersive X‐ray spectroscopy (EDX) and Fourier transform infrared (FT‐IR) techniques. The phase structure of the Ca2MgSi2O7:Eu2+,Dy3+ phosphor was akermanite type, which is a member of the melilite group. The surface morphology of the sintered phosphor was not uniform and phosphors aggregated tightly. EDX and FT‐IR spectra confirm the elements present in the Ca2MgSi2O7:Eu2+,Dy3+ phosphor. Under UV excitation, a broadband emission spectrum was found. The emission spectra observed in the green region centered at 535 nm, which is due to the 4f–5d transition. The mechanoluminescence (ML) intensity of the prepared phosphor increased linearly with increases in the mechanical load. The ML spectra were similar to the photoluminescence (PL), which indicates that ML is emitted from the same emitting center of Eu2+ ions as PL. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

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