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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 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   

3.
Rare‐earth ions play an important role in eco‐friendly solid‐state lighting for the lighting industry. In the present study we were interested in Eu3+ ion‐doped inorganic phosphors for near ultraviolet (UV) excited light‐emitting diode (LED) applications. Eu3+ ion‐activated SrYAl3O7 phosphors were prepared using a solution combustion route at 550°C. Photoluminescence characterization of SrYAl3O7:Eu3+ phosphors showed a 612 nm emission peak in the red region of the spectrum due to the 5D07F2 transition of Eu3+ ions under excitation at 395 nm in the near‐UV region and at the 466 nm blue excitation wavelength. These red and blue emissions are supported for white light generation for LED lighting. Structure, bonding between each element of the sample and morphology of the sample were analysed using X‐ray diffraction (XRD) and scanning electron microscopy (SEM), which showed that the samples were crystallized in a well known structure. The phosphor was irradiated with a 60Co‐γ (gamma) source at a dose rate of 7.2 kGy/h. Thermoluminescence (TL) studies of these Eu3+‐doped SrYAl3O7 phosphors were performed using a Nucleonix TL 1009I TL reader. Trapping parameters of this phosphor such as activation energy (E), order of kinetics (b) and frequency factor (s) were calculated using Chen's peak shape method, the initial rise method and Ilich's method.  相似文献   

4.
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   

5.
Direct white light emitting phosphors play a significant role in the display industry due to their ability to improve the quality, efficiency, and versatility of lighting sources used in most of the displays. The currently investigated phosphor SrZr2CaLa2O8:Eu3+ was prepared by a conventional solid-state reaction method. It has been observed that the stoichiometric ratio of all precursors plays an important role in determining the characteristics of the final phosphor. From X-ray diffraction (XRD) analysis, the phosphor was observed to have a hexagonal phase and a crystal size of ~28 nm. Scanning electron microscopy (SEM) observations revealed a cluster of rod-like structures with an average diameter of ~0.2 μm. The excitation peak maximum observed at 280 nm is due to charge transfer between Eu3+-O2− ions. The energy transitions 7F05L6 and 7F05D2 are responsible for the appearance of other excitation peaks at ultraviolet (UV) (395 nm), blue (~467 nm), green (~540 nm), orange (~590 nm), and red (~627 nm) attributed to 5D07FJ (J = 0–4) transitions of europium ion (Eu3+). The Commercial International de I'Eclairage (CIE) chromaticity coordinates were estimated to be (0.37, 0.0.33) and (0.67, 0.33) for the emissions corresponding to 395 and 590 nm, respectively. The characteristic emissions of Eu3+ ions allow this novel phosphor to be used to generate direct white light in light-emitting diodes (LEDs), which is otherwise difficult to achieve in single-component systems.  相似文献   

6.
A novel blue green‐emitting phosphor Ba2ZnSi2O7 : Eu2+ was prepared by combustion synthesis method and an efficient bluish green emission under from ultraviolet to visible light was observed. The emission spectrum shows a single intensive band centered at 503 nm, which corresponds to the 4f65d1 → 4f7 transition of Eu2+. The excitation spectrum is a broad band extending from 260 to 465 nm, which matches the emission of ultraviolet light‐emitting diodes (UV‐LEDs). The effect of doped Eu2+ concentration on the emission intensity of Ba2ZnSi2O7 : Eu2+ was also investigated. The result indicates that Ba2ZnSi2O7 : Eu2+ can be potentially useful as a UV radiation‐converting phosphor for white light‐emitting diodes. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

7.
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   

8.
A series of Eu3+‐, Ce3+‐, Dy3+‐ and Tb3+‐doped (Y,Gd)BO3 phosphors was synthesized by a solid‐state diffusion method. X‐Ray diffraction confirmed their hexagonal structure and the scanning electron microscopy results showed crystalline particles. The excitation spectra revealed that (Y,Gd)BO3 phosphors doped with Eu3+, Ce3+ , Dy3+ and Tb3+ are effectively excited with near UV‐light of 395 nm/blue light, 364, 351 and 314 nm, respectively. Photoluminescence spectra of Eu3+‐, Ce3+‐ and Tb3+/Dy3+‐doped phosphor showed intense emission of reddish orange, blue and white light, respectively. The phosphor Y0.60Gd0.38BO3:Ce0.02 showed CIE 1931 color coordinates of (0.158, 0.031) and better color purity compared with commercially available blue BAM:Eu2+ phosphor. The phosphor (Y,Gd)BO3 doped with Eu3+, Dy3+ and Tb3+ showed CIE 1931 color coordinates of (0.667, 0.332), (0.251, 0.299) and (0.333, 0.391) respectively. Significant photoluminescence characteristics of the prepared phosphors indicate that they might serve as potential candidates for blue chip and near‐UV white light‐emitting diode applications. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

9.
The new borate phosphor CaB2O4:Eu3+ was synthesized by solid‐state method and their photoluminescence properties were investigated. The results show that the pure phase of CaB2O4 could be available at 900°C, CaB2O4:Eu3+ phosphor could be effectively excited by the near ultraviolet light (NUV) (392 nm), and the luminescent intensity of CaB2O4:Eu3+ phosphor reached to the highest when the doped‐Eu3+ content was 4 mol%. The emission spectra of CaB2O4:Eu3+ phosphor could exhibit red emission at 612 nm and orange emission at 588 nm, which are ascribed to the 5D07F2 and 5D07F1 transitions of Eu3+ ions. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

10.
A blue‐emitting phosphor Ca12Al14O32F2:Eu2+ was synthesized using a high‐temperature solid‐state reaction under a reductive atmosphere. The X‐ray diffraction measurements indicate that a pure phase Ca12Al14O32F2:Eu2+ can be obtained for low doping concentration of Eu2+. The phosphor has a strong absorption in the range 270–420 nm with a maximum at ~340 nm and blue emission in the range 400–500 nm with chromatic coordination of (0.152, 0.045). The optimal doping concentration is ~0.24. In addition, the luminescence properties of the as‐synthesized phosphor were evaluated by comparison with those of Ca12Al14O32Cl2:Eu2+ and the commercially available phosphor BaMgAl10O17:Eu2+. The emission intensity of Ca12Al14O32F2:Eu2+ was ~72% that of BaMgAl10O17:Eu2+ under excitation at λ = 375 nm. The results indicate that Ca12Al14O32F2:Eu2+ has potential application as a near‐UV‐convertible blue phosphor for white light‐emitting diodes.  相似文献   

11.
Novel red‐emitting phosphors, Eu3+‐activated M7Sn(PO4)6 (M = Sr, Ba), were synthesized at 1200°C by conventional solid‐state reaction method. The luminescent properties of M7Sn(PO4)6:Eu3+ (M = Sr, Ba) phosphors were investigated, and the critical concentration of the activator (Eu3+) concentration were found to be 0.175 mol and 0.21 mol per formula unit for Sr7‐xSn(PO4)6:xEu3+ and Ba7‐xSn(PO4)6:xEu3+, respectively. These phosphors presented red luminescence under the excitation of 395 or 465 nm, perfectly matching with the emissions wavelength of near‐ultraviolet (UV) light‐emitting diodes (LEDs) and InGaN blue LED.  相似文献   

12.
Red‐emitting Li2Sr1‐3x/2EuxSiO4 0≤x≤0.5) phosphors were synthesized at 900°C in air by a solid‐state reaction. The synthesized phosphors were characterized by X‐ray powder diffraction, photoluminescence (PL) excitation (PLE) and PL spectra. The results from the PLE spectra suggest that the strong 394 nm excitation peak associated with the 5L6 state of Eu3+ ions is of significance for near ultraviolet pumped white light‐emitting diodes and solid‐state lighting. It is also noted that the position of the charge transfer state of Eu3+ ions shifts towards the higher energy side (blue shift) by increasing the content of Eu3+ ions. The predominant emissions of Eu3+ ions under 394 nm excitation are observed at 580, 593, 614, 656 and 708 nm, which are attributed to the 5D07FJ (J = 0, 1, 2, 3 and 4), respectively. The PL results reveal that the optimal content of the red‐emitting Li2Sr1‐3x/2EuxSiO4 phosphors is x = 0.475. Simulation of the white light excited by 394 nm near ultraviolet light has also been carried out for its potential white light‐emitting diode applications. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

13.
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   

14.
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   

15.
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   

16.
This study synthesized BaMoO4:Eu3+ red phosphors using the microwave method. In addition, the phase composition, morphology, and luminescence properties of the red phosphors were characterized using X-ray diffraction, field-scanning electron microscopy, and photoluminescence spectroscopy. The results revealed that doping red phosphors with different concentrations of Eu3+ does not change the crystal structure of the matrix material. The BaMoO4:Eu3+ phosphors exhibited micron-scale irregular polyhedra, which could be excited by ultraviolet light with a wavelength of 395 nm to induce red-light emission. The optimal dosage of Eu3+ was 0.08, and the chromaticity coordinates of BaMoO4:0.08Eu3+ phosphors were (0.5869, 0.3099). White light-emitting diode (w-LED) devices manufactured by using a combination of BaMoO4:0.08Eu3+ phosphor and commercially available phosphors exhibited good white-light emission under the excitation of an ultraviolet chip. The BaMoO4:0.08Eu3+ red phosphors that rapidly synthesized under the microwave field are expected to be used in w-LED devices.  相似文献   

17.
A series of Mg2Y2Al2Si2O12:Dy3+,Eu3+ was prepared using a solid-state method, and the phosphor emitted white light by tuning the ratio of Dy3+/Eu3+. The effects of La3+/Lu3+ on the structure and luminescence properties of Mg2Y2Al2Si2O12:Dy3+,Eu3+ were explored. Under the influence of bond length and twist, the luminescence intensity of the materials increased first and then decreased under excitation with ultraviolet light. The lattice distortion of the trivalent cation La3+-substituted Mg2Y2Al2Si2O12:Dy3+ and Eu3+ phosphors was reduced, the symmetry of polyhedron occupied by the luminescence centre improved, and the thermal stability of the luminescence centre improved to a certain extent. White light emitting diodes (LEDs) were fabricated by combining a 370 nm LED chip and the Mg2Y2Al2Si2O12:Dy3+,Eu3+,La3+ (Mg2Y2Al2Si2O12:Dy3+,Eu3+,Lu3+) phosphor. The results showed that Mg2Y2Al2Si2O12:Dy3+,Eu3+,La3+/Lu3+ may have potential application in the area of white LEDs.  相似文献   

18.
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   

19.
A novel blue‐emitting phosphor, Eu2+‐doping Al4B2O9, was prepared via a modified solid‐state reaction. Al4B2O9:Eu2+ nanoparticles with diameters varying in a range from 20 to 50 nm were obtained using urea as an auxiliary reagent at the optimum temperature of 850°C. The crystallization and particle sizes of Al4B2O9:Eu2+ were investigated using powder X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Photoluminescence (PL) results showed that Al4B2O9:Eu2+ phosphor could be efficiently excited by the ultraviolet region from 240 to 410 nm, exhibiting bright blue emission. Further investigation on concentration‐dependent emission spectra indicated that the Al3.997B2O9:Eu2+0.003 phosphor exhibited the strongest luminescent, and the relative PL intensity decreased with increasing Eu2+ concentration due to concentration quenching. In addition, the concentration quenching for the one‐Eu‐site emission centers was caused by the electric multipole–multipole interaction. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

20.
Europium (Eu)3+‐substituted La2Li0.5Al0.5O4 red emitting phosphors were prepared by a conventional high‐temperature solid‐state reaction method. Powder X‐ray diffraction, diffuse reflectance spectra and spectrofluorometry were used as vital characterizing tools for the phosphors. The Eu concentration dependence luminescence properties and Judd–Ofelt intensity parameters were investigated and calculated, respectively. All compositions showed an orange red emission (due to the magnetic and electric dipole transitions of the Eu3+ ion) with the appropriate Commission Internationale de l'Eclairage (CIE) colour gamut under near ultraviolet or blue ray light excitation. The calculated critical distance showed that the energy transfer occured between Eu to Eu via an exchange mechanism. The Eu1.4La0.6Li0.5Al0.5O4 composition showed the highest red emission intensity with CIE colour saturation compared with that of the commercial Eu‐activated yttrium oxysulfide red phosphor.  相似文献   

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