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1.
In this article Ca1‐xTiO3:xEu3+ single crystalline particles with a cubic morphology and average size of 248 to 815 nm were synthesized by a solvothermal method. The structural and optical properties of the Ca1‐xTiO3:xEu3+ cubes were investigated, the formation mechanism of the cubes were analyzed and discussed, and the influence of Eu doping content and cubic size on the photoluminescence were examined. The differences in the photoluminescence between Ca1‐xTiO3:xEu3+ cubic crystals and nanoparticles was analyzed. It was found that an addition of a small amount of water can substantially reduce the size of the cubes. An obvious red emission band centered at 615 nm was observed under the excitation at 395 nm for the cubes. Our results demonstrate CaTiO3 cubes are good host materials for designing red phosphors.  相似文献   

2.
In this article we report Eu3+ luminescence in novel K3Ca2(SO4)3Cl phosphors prepared by wet chemical methods. The Eu3+ emission was observed at 594 nm and 615 nm, keeping the excitation wavelength constant at 396 nm nearer to light‐emitting diode excitation, Furthermore, phosphors were characterized by X‐ray diffraction for the confirmation of crystallinity. The variation of the photoluminescence intensity with impurity concentration has also been discussed. Thus, prominent emission in the red region makes prepared phosphors more applicable for white light‐emitting diodes. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

3.
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   

4.
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   

5.
In the recent few years, Eu2+- and Mn4+-activated phosphors are widely used as potential colour converters for indoor plant cultivation lighting application due to their marvellous luminescence characteristics as well as low cost. In this investigation, we synthesized novel red colour-emitting Ca(2−x)Mg2(SO4)3:xmol% Eu2+ (x = 0–1.0 mol%) phosphors via a solid-state reaction method in a reducing atmosphere. The photoluminescence (PL) excitation spectra of synthesized phosphors exhibited a broad excitation band with three excitation bands peaking at 349 nm, 494 nm, and 554 nm. Under these excitations, emission spectra exhibited a broad band in the red colour region at ~634 nm. The PL emission intensity was measured for different concentrations of Eu2+. The maximum Eu2+ doping concentration in the Ca2Mg2(SO4)3 host was observed for 0.5 mol%. According to Dexter theory, it was determined that dipole–dipole interaction was responsible for the concentration quenching. The luminous red colour emission of the sample was confirmed using Commission international de l'eclairage colour coordinates. The results of PL excitation and emission spectra of the prepared phosphors were well matched with excitation and emission wavelengths of phytochrome PR. Therefore, from the entire investigation and obtained results it was concluded that the synthesized Ca0.995Mg2(SO4)3:0.5mol%Eu2+ phosphor has huge potential for plant cultivation application.  相似文献   

6.
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   

7.
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   

8.
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   

9.
BaGd2‐xO4:xEu3+ and Ba1‐yGd1.79‐2yEu0.21Na3yO4 phosphors were synthesized at 1300°C in air by conventional solid‐state reaction method. Phosphors were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence excitation (PLE) spectra, photoluminescence (PL) spectra and thermoluminescence (TL) spectra. Optimal PL intensity for BaGd2‐xO4:xEu3+ and Ba1‐yGd1.79‐2yEu0.21Na3yO4 phosphors at 276 nm excitation were found to be x = 0.24 and y = 0.125, respectively. The PL intensity of Eu3+ emission could only be enhanced by 1.3 times with incorporation of Na+ into the BaGd2O4 host. Enhanced luminescence was attributed to the flux effect of Na+ ions. However, when BaGd2O4:Eu3+ phosphors were codoped with Na+ ions, the induced defects confirmed by TL spectra impaired the emission intensity of Eu3+ ions. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

10.
KBaPO4 luminescent powdered phosphors doped with rare earth elements (RE = Sm3+,Eu3+,Dy3+) were successfully synthesized using a wet chemical method to identify the most suitable phosphor for solid‐state lighting based on the measurement of their emission spectra at excitation wavelengths. The X‐ray diffraction pattern of the as‐prepared KBaPO4 was well matched with its standard JCPDS file no. 330996, indicating the formation of the desired compound. Scanning electron microscopy images revealed irregular morphology, the material crystallized particles aggregated and were non‐uniform with particle sizes ranging from 1 to 100 μm. Photoluminescence excitation and emission spectra clearly indicated that the phosphor containing the Sm3+‐activated KBaPO4 phosphors could be efficiently excited at 403 nm and exhibited an emission mainly including two wavelength peaks at 559 nm and 597 nm. The phosphor containing the Eu3+‐activated KBaPO4 phosphors could be efficiently excited at 396 nm and exhibited a bright red emission mainly including two wavelength peaks at 594 nm and 617 nm. The phosphor containing the Dy3+‐activated KBaPO4 phosphors could be efficiently excited at 349 nm and exhibited wavelength peaks at 474 nm and 570 nm.  相似文献   

11.
The Eu2+/Eu3+ mixed valence phosphor Ca2SiO2F2:Eu2+/Eu3+ was prepared using a solid‐state reaction synthesis method in a CO atmosphere, and the optical properties were investigated. The spectroscopic properties revealed that Ca2+ ions were occupied by both Eu2+ and Eu3+ ions in Ca2SiO2F2, and both ions were able to generate their characteristic emissions. A broad 5d → 4f Eu2+ band at ~470 nm and narrow 4f → 4f Eu3+ peaks upon excitation with n‐UV light were observed. The ratio between Eu2+ and Eu3+ emissions changed regularly, and the relative intensity of the red component from Eu3+ became systematically stronger with increasing overall Eu content. As a result, the emission color of these phosphors can be tunable from blue to pink under n‐UV light excitation.  相似文献   

12.
Eu3+‐activated Y(P,V)O4 phosphors were prepared by the EDTA sol‐gel method, and the corresponding morphologies and luminescent properties were investigated. The sample particles were relatively spheroid with size of 2–3 µm and had a smooth surface. The excitation spectra for Y(P,V)O4:Eu3+ consisted of three strong excitation bands in the 200–350 nm range, which were attributed to a Eu3+‐ O2? charge‐transfer band and 1A1?1 T1/1 T2 transitions in VO43?. The as‐synthesized phosphors exhibited a highly efficient red luminescence at 613 nm due to the Eu3+ 5D0?7 F2 electric dipole transition. With the increase in the V5+/P5+ ratio, the luminescence intensity of the red phosphor under UV excitation was greatly improved due to enhanced VO43? → Eu3+ energy transfer. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

13.
Ca2Al2O5:Eu3+, Ca2Al2O5:Dy3+ and Ca2Al2O5:Tb3+ phosphors were synthesized using a combustion synthesis method. The prepared phosphors were characterized by X‐ray powder diffraction for phase purity, by scanning electron microscopy for morphology, and by photoluminescence for emission and excitation measurements. The Ca2Al2O5:Eu3+ phosphors could be efficiently excited at 396 nm and showed red emission at 594 nm and 616 nm due to 5D0 → 7F1 and 5D0 → 7F2 transitions. Dy3+‐doped phosphors showed blue emission at 482 nm and yellow emission at 573 nm. Ca2Al2O5:Tb3+ phosphors showed emission at 545 nm when excited at 352 nm. Concentration quenching occurred in both Eu3+ and Dy3+phosphors at 0.5 mol%. Photoluminescence results suggested that the aluminate‐based phosphor could be a potential candidate for application in environmentally friendly based lighting technologies.  相似文献   

14.
The present communication is strongly focused on the investigation of synthesis, structural and luminescence properties of cerium (Ce3+)- and europium (Eu3+)-activated Zn4Al22O37 phosphors. Ce3+- and Eu3+-doped Zn4Al22O37 novel phosphors were prepared using a solution combustion synthesis route. Structural properties were studied using powder X-ray diffraction and high-resolution transverse electron microscopy. The optical properties were studied using ultraviolet–visible light spectroscopy and Fourier transform infrared spectroscopy; luminescence properties were studied using a photoluminescence (PL) technique. The crystal structure of the prepared Zn4Al22O37 host and Ce3+- and Eu3+-activated Zn4Al22O37 phosphors was investigated and was found to have a hexagonal structure. The measured PL emission spectrum of the Ce3+-doped Zn4Al22O37 phosphor showed an intense and broad emission band centred at 421 nm under a 298 nm excitation wavelength. By contrast, the Eu3+-doped Zn4Al22O37 phosphor exhibited two strong and intense emission bands at approximately 594 nm (orange) and 614 nm (red), which were monitored under 395 nm excitation. The Commission Internationale de l’Eclairage (CIE) colour coordinates of the Ce3+-doped Zn4Al22O37 were investigated and found to be x = 0.1567, y = 0.0637 (blue) at 421 nm and for Eu3+-doped Zn4Al22O37 were x = 0.6018, y = 0.3976 (orange) at 594 nm and x = 0.6779, y = 0.3219 (red) at 614 nm emission. The luminescence behaviour of the synthesized phosphors suggested that these phosphors may be used in lighting applications.  相似文献   

15.
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   

16.
In this article, we report the synthesis of Na2Sr1‐x(PO4)F:Eux phosphor via a combustion method. The influence of different annealing temperatures on the photoluminescence properties was investigated. The phosphor was excited at both 254 and 393 nm. Na2Sr1‐x(PO4)F:Eux3+ phosphors emit strong orange and red color at 593 and 612 nm, respectively, under both excitation wavelengths. Na2Sr1‐x(PO4)F:Eux3+ phosphors annealed at 1050°C showed stronger emission intensity compared with 600, 900 and 1200°C. Moreover, Na2Sr1‐x(PO4)F:Eux3+ phosphor was found to be more intense when compared with commercial Y2O3:Eu3+ phosphor. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

17.
The luminescent properties of europium (Eu)‐ and dysprosium (Dy)‐co‐doped K3Ca2(SO4)3Cl halosulfate phosphors were analyzed. This paper reports the photoluminescence (PL) properties of K3Ca2(SO4)3Cl microphosphor doped with Eu and Dy and synthesized using a cost‐effective wet chemical method. The phosphors were characterized by X‐ray diffraction and scanning electron microscopy. The CIE coordinates were calculated to display the color of the phosphor. PL emission of the prepared samples show peaks at 484 nm (blue), 575 nm (yellow), 594 nm (orange) and 617 nm (red). The emission color of the Eu,Dy‐co‐doped K3Ca2(SO4)3Cl halophosphor depends on the doping concentration and excitation wavelength. The addition of Eu in K3Ca2(SO4)3Cl:Dy greatly enhances the intensity of the blue and yellow peaks, which corresponds to the 4 F9/26H15/2 and 4 F9/26H13/2 transitions of Dy3+ ions (under 351 nm excitation). The Eu3+/Dy3+ co‐doping also produces white light emission for 1 mol% of Eu3+, 1 mol% of Dy3+ in the K3Ca2(SO4)3Cl lattice under 396 nm excitation, for which the calculated chromaticity coordinates are (0.35, 0.31). Thus, K3Ca2(SO4)3Cl co‐doped with Eu/Dy is a suitable candidate for NUV based white light‐emitting phosphors technology. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

18.
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   

19.
A series of blue phosphors Ca1.98–xMxPO4Cl:0.02Eu2+ (M = Mg and Sr) with different values of x were synthesized using a high‐temperature solid‐state reaction. X‐Ray diffraction and photoluminescence measurements were used to study the phase structure and luminescence properties. Ca2PO4Cl:0.02Eu2+ exhibits a tunable emission intensity and color due to the incorporation of Sr2+ or Mg2+. The incorporation of Sr2+ reduces the luminescence intensity and results in a slight red shift in the emission band. The incorporation of Mg2+ results in enhanced emission and a clear blue shift in the emission band along with a tunable chromatic coordination. Under excitation at λ = 334 nm, the emission intensity of the Mg2+‐doped Ca2PO4Cl:0.02Eu2+ is found to be 250% that of Ca2PO4Cl:0.02Eu2+. The luminescence behaviors of the as‐synthesized phosphors are discussed according to the host crystal structure and site occupancy of Eu2+. The results indicate that Mg2+‐doped Ca2PO4Cl:Eu2+ is more applicable as a near‐UV‐convertible blue phosphor for white light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

20.
Ca2MgSi2O7:Ce3+, Ca2MgSi2O7:Eu2+ and Ca2MgSi2O7:Eu2+,Ce3+ phosphors were prepared using the solid‐state reaction method. The crystal structures of the sintered phosphors were of melilite type, which has a tetragonal crystallography. The chemical compositions of the sintered phosphors was confirmed by energy dispersive X‐ray spectroscopy. The different thermoluminescence kinetic parameters [activation energy (E), frequency factor (s) and order of the kinetics (b)] of these phosphors were evaluated and compared using the peak shape method. Under ultraviolet excitation, the emission spectra of both Ca2MgSi2O7:Eu2+ and Ca2MgSi2O7:Eu2+,Ce3+ phosphors were composed of a broad emission band peaking at 530 nm. When the Ca2MgSi2O7:Eu2+ phosphor is co‐doped with Ce3+ ions, photoluminescence, afterglow and mechanoluminescence intensity was strongly enhanced. Ca2MgSi2O7:Eu2+ showed some afterglow with a short persist time. On incorporation of Ce3+, efficient energy transfer from Ce3+ to Eu2+ was found and the emission intensity of Eu2+ was enhanced. The mechanoluminescence intensities of Ca2MgSi2O7:Ce3+, Ca2MgSi2O7:Eu2+ and Ca2MgSi2O7:Eu2+,Ce3+ phosphors increased proportionally increased with the increase in impact velocity, which suggests that these phosphors can be used as sensors to detect stress in an object.  相似文献   

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