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1.
In this work, a new red phosphor with high color purity, Eu3+ ions doped Ba(Mg1/3Nb2/3)O3 phosphor has been prepared by wet chemical method. The structure analysis suggests BMN:x%Eu phosphors have a hexagonal phase and Ba2+ ions are replaced by Eu3+ ions in BMN. Upon excitation of NUV light, the BMN:x%Eu phosphors emit strong red light around 615?nm, derived from the 5D0-7F2 transition of Eu3+ ions. The relationship between luminescent properties and structure of BMN:x%Eu was discussed. The Judd-Ofelt intensity parameters (Ω2, Ω4) were calculated to analyze the asymmetry of the Eu3+ ions site occupancy further, and the quantum efficiency of BMN:3%Eu was found to be 77.26%. In addition, the decay curve indicates the decay time(τ) of BMN:3%Eu is determined to be 1.34?ms and Eu3+ ions occupy only one type of site. The CIE chromaticity coordinate (0.656,0.344) of BMN:3%Eu is quite close to the red phosphors standard value (0.670, 0.330), which indicates BMN:x%Eu can be a suitable red phosphor used in NUV-based white LEDs.  相似文献   

2.
A series of LiCaGd(WO4)3 : xEu3+ (0 ≤ x ≤ 1.0) red phosphors with tetragonal scheelite structure were synthesized via the conventional solid-state reaction. Their crystal structure, photoluminescence excitation (PLE), and photoluminescence (PL) spectra, thermal stability and quantum efficiency were investigated. The phosphors exhibit a typical red light upon 395 nm near ultraviolet excitation, and the strongest emission peak at 617 nm is dominated by the 5D07F2 transition of Eu3+ ions. The PL intensity of the phosphors gradually increases with the increase of Eu3+ doping concentration, and the concentration quenching phenomenon is hardly observed. The quantum efficiency and the color purity of the phosphor reach maximum values of about 94.2 and 96.6% at x = 1.0, respectively. More importantly, LiCaGd(WO4)3:xEu3+ phosphors have prominent thermal stability. The temperature-dependent PL intensity of the phosphors at 423 K is only reduced to 89.1% of the PL intensity at 303 K, which is superior to that of commercial red phosphors Y2O3:Eu3+. Finally, LiCaGd(WO4)3:Eu3+ phosphor is packaged with near ultraviolet InGaN chips to fabricate white light emitting diodes, which has a low color temperature (CCT = 4622 K) and a high color rendering index (CRI= 89.6).  相似文献   

3.
《Ceramics International》2016,42(12):13841-13848
A series of Eu3+- or Dy3+-doped and Eu3+/Dy3+ co-doped Y2WO6 in pure phase was synthesized via high-temperature solid-state reaction. X-ray diffraction, diffuse reflection spectra, photoluminescence excitation and emission spectra, the CIE chromaticity coordinates and temperature-dependent emission spectra were exploited to investigate the phosphors. Upon UV excitation at 310 nm, efficient energy transfer from the host Y2WO6 to dopant ions in Eu3+ or Dy3+ single-doped samples was demonstrated and those phosphors were suitable for the UV LED excitation. The intense red emission was observed in Y2WO6: Eu3+, and blue and yellow ones were observed in Y2WO6: Dy3+. Concentration quenching in Y2WO6: Dy3+ phosphors could be attributed to the electric dipole-dipole interaction. In Eu3+/Dy3+ co-doped Y2WO6 phosphors energy transfer process only took place from the host to Eu3+/Dy3+ ions and warm white-light emission can be obtained by adjusting the dopant concentrations. The temperature-dependent luminescence indicated Eu3+/Dy3+ co-doped Y2WO6 was thermally stable. Our overall results suggested that Y2WO6: Ln3+ (Ln3+=Eu3+, Dy3+) as warm white-light emitting host-sensitized phosphor might be potentially applied in WLEDs.  相似文献   

4.
This work demonstrates the luminescent properties of Ba3Lu2B6O15 phosphors doped with Eu3+ ions for the first time. The Ba3(Lu1–xEux)2B6O15 (x = 0.01–0.375) phosphors have been prepared using a multi-step high-temperature solid-state synthesis. X-ray diffraction measurements verify the successful isomorphic substitution of the Lu3+ sites by the Eu3+ ions. The luminescence properties and its dependence on the crystal structure of Ba3(Lu1–xEux)2B6O15 have been reported in this work. There are two nonequivalent sites in this crystal structures occupied by lutetium, both of them can be consistently substituted by the Eu3+ ions. The highest emission intensity with quantum yield of 17% was demonstrated by Ba3(Lu0.82Eu0.18)2B6O15 powder. Increase of Eu3+ doping concentration leads to gradual change of chromaticity from violet to red. It was expected that Ba3(Lu1–xEux)2B6O15 phosphors can be used as a phosphor with predicted chromaticity under LED excitation.  相似文献   

5.
CaGd2(WO4)4:Eu3+ phosphors with controllable morphology were synthesized via the hydrothermal method. The influences of pH value, reaction time and Eu3+ concentration on the crystal structure, morphology, and photoluminescence properties of CaGd2(WO4)4:Eu3+ were studied. The pure tetragonal structure CaGd2(WO4)4 is obtained when the pH value is 8 and 9. Furthermore, by altering the pH value of the reaction solution, the morphologies of the CaGd2(WO4)4:Eu3+ phosphors evolve from spindle-shaped grains to tetragonal plate-like grains and finally to aggregated bulk particles. Under the 394 nm excitation, the phosphors display a bright red emission corresponding to the characteristic 4f-4f transitions of Eu3+, and the intensity of emission peaks depends mainly on the pH value, the reaction time, and the Eu3+ concentration. The optimum photoluminescence performance is achieved for CaGd2-x(WO4)4:xEu3+ (x = 1) phosphor synthesized at pH = 8 under the reaction time of 16 h. Finally, the thermal stability of the phosphors is analyzed at different ambient temperatures.  相似文献   

6.
A new series of Li3Ba2La3(1-x)Y3x(MoO4)8 microwave dielectric ceramics were prepared by a conventional solid-state reaction method. The Rietveld refinement results further confirm that Li3Ba2La3(1-x)Y3x(MoO4)8 belongs to a monoclinic system with space group C2/c. Scanning electron microscopy results reveal that Li3Ba2La3(1-x)Y3x(MoO4)8 ceramics can be well sintered at a low sintering temperature. In addition, the permittivity (εr) of Li3Ba2La3(1-x)Y3x(MoO4)8 ceramics was found to decrease gradually with increasing substitution content of Y3+, while the quality factor (Qxf) and temperature coefficient of resonant frequency (τf) increase with x monotonously. The x?=?0.4 ceramic sintered at 700?°C for 4?h possesses optimum microwave dielectric properties of εr ~ 14.4, Qxf ~ 14,994?GHz (at 9.0?GHz) and τf ~?+?6.9?ppm/°C. Particularly, no chemical reaction between the matrix phase and Ag metal suggests that the Li3Ba2La1.8Y1.2(MoO4)8 ceramic might be a promising candidate for low-temperature co-fired ceramic applications.  相似文献   

7.
《Ceramics International》2023,49(5):7534-7545
Eu3+-doped BaLa2WO7 and SrLa2WO7 phosphors were prepared using the conventional solid-state reaction synthesis. The experiments have confirmed that the luminescence properties are completely different although they the isostructural monoclinic structure with a monoclinic space group of P21/b: compared with SrLa2WO7:Eu3+, BaLa2WO7:Eu3+ has stronger luminescence and higher thermal stability. The dynamic characteristics were studied via the laser site-selective excitation and luminescence technique. The two distinct Eu3+ centers Eu3+(A) and Eu3+(B) were confirmed corresponding to the substitution for La1 and La2, respectively. Eu3+(A) could transfer energy to Eu3+(B) in BaLa2WO7:Eu3+, but Eu3+(B) cannot realize back transfer to Eu3+(A). However, a mutual energy transfer could be achieved between Eu3+(A) and Eu3+(B) in SrLa2WO7:Eu3+ resulting in excitation energy diffusion. The energy dispersion may cause the excited electrons to be trapped in some defects and impurities, thereby reducing the luminescence effect. The results could help develop new reddish-orange emitting materials by introducing Eu3+ as a structural probe for doping sites and microstructure.  相似文献   

8.
Using the conventional high temperature solid‐state reaction method Ba2Ca(PO4)2:Eu2+ phosphors were prepared. The phase structure, photoluminescence (PL) properties, and the PL thermal stability of the samples were investigated, respectively. Under the excitation at 365 nm, the phosphor exhibited an asymmetric broad‐band blue emission with peak at 454 nm, which is ascribed to the 4f–5d transition of Eu2+. It was further proved that the dipole–dipole interactions results in the concentration quenching of Eu2+ in Ba2Ca1?x (PO4)2:xEu2+ phosphors. When the temperature turned up to 150°C, the emission intensity of Ba2Ca0.99(PO4)2:0.01Eu2+ phosphor was 59.07% of the initial value at room temperature. The activation energy ΔE was calculated to be 0.30 eV, which proved the good thermal stability of the sample. All the properties indicated that the blue‐emitting Ba2Ca(PO4)2:Eu2+ phosphor has potential application in white LEDs.  相似文献   

9.
This work presents the ultraviolet–visible spectroscopic properties of Ba3Y2(BO3)4:Ce3+,Tb3+ phosphors prepared by a high‐temperature solid‐state reaction. Under ultraviolet light excitation, tunable emission from the blue to yellowish‐green region was obtained by changing the doping concentration of Tb3+ when the content of Ce3+ is fixed. The efficient energy transfer process between Ce3+ and Tb3+ ions was observed and confirmed in terms of corresponding excitation and emission spectra. In addition, the energy transfer mechanism between Ce3+ and Tb3+ was proved to be dipole–dipole interaction in Ba3Y2(BO3)4:Ce3+,Tb3+ phosphor. By utilizing the principle of energy transfer and appropriate tuning of Ce3+/Tb3+ contents, Ba3Y(BO3)4:Ce3+,Tb3+ phosphors can have potential application as an UV‐convertible phosphor for near‐UV excited white light‐emitting diodes.  相似文献   

10.
Rare earth ions’ site occupation is significant for studying luminescence properties by changing the host composition. The (Ba1-xSrx)9Lu2Si6O24:Eu2+ (x = 0-0.4) tunable-color phosphors were synthesized via a high temperature solid-state reaction. With the Sr2+ ions concentration increase, the luminescent color could be tuned from blue to green. This phenomenon is discussed in detail through the ions occupation in the host lattice. More importantly, the temperature-dependent luminescence of (Ba1-xSrx)9Lu2Si6O24:Eu2+ phosphors was investigated and exhibited excellent thermal stability. Furthermore, white LED device has been fabricated using (Ba1-xSrx)9Lu2Si6O24:Eu2+ phosphor mixed with commercial red phosphor Sr2Si5N8:Eu3+ combined with a 370 nm UV-chip. This device showed correlated color temperature (CCT) of 5125 K and high color render index (CRI) of 91. This phosphor will be a promising candidate as a tunable-color phosphor for UV-based white LEDs.  相似文献   

11.
In this paper, Y4GeO8:Bi3+,Eu3+ phosphor with dual emission centers was elaborated via conventional solid-state reaction technology. Thorough research on the structure, morphology, and luminous properties of Y4GeO8:Bi3+,Eu3+ phosphor, the potential applications in optical thermometry were investigated by means of fluorescence intensity ratio and thermochromic techniques. Under 290 and 347 nm excitation, Y4GeO8:Bi3+,Eu3+ phosphor presents broadband emission from 3P1 → 1S0 transition of Bi3+ ions and characteristic emission peaks from 4f–4f transition of Eu3+ ions. Outstanding temperature-sensing capabilities are acquired from Y4GeO8:Bi3+,Eu3+ phosphor. The maximum relative sensitivity (Sr) can attain 1.51% K−1 (λex = 290 nm). With temperature raising (303–513 K), the emitted color of Y4GeO8:Bi3+,Eu3+ phosphor (λex = 290 nm) shifts from faint yellow to red with a high chromaticity shift (0.180), which can be distinguished by the unaided eye clearly. Our results indicate that Y4GeO8:Bi3+,Eu3+ phosphor has potential applications in optical temperature measurement and high-temperature safety marker.  相似文献   

12.
Color tunable yellow-emitting phosphors of Sr5−5xEu5x(PO4)2SiO4 (x = 0.05-0.15) were prepared by conventional solid-state reaction method. The X-ray powder diffraction patterns, the photoluminescence excitation and emission spectra were measured. The main excitation bands of the phosphors locate at a broad band extending from 300 to 500 nm, which can match the emission of ultraviolet- and blue-emitting diode chips. The tunable luminescence color was realized by the changing Eu2+ doping in Sr5(PO4)2SiO4. The structure and luminescence properties were investigated. Sr5−5x(PO4)2SiO4:Eu5x displays two typical luminescence centers, which originate from two different Sr2+ (Eu2+) sites in the host. The site-occupation, the luminescence intensity and energy transfer between the Eu2+ ions occupying two different crystallographic Sr2+ sites were discussed on the base of the luminescence spectra and crystal structure. This is helpful to improve this phosphor for a potential application as a white light emitting diode phosphor.  相似文献   

13.
A series of Ce3+, Tb3+, Eu3+ tri‐doped Ba2Y(BO3)2Cl red‐emitting phosphor have been synthesized by solid‐state method. The Ce3+→Tb3+→Eu3+ energy‐transfer scheme has been proposed to realize the sensitization of Eu3+ ion emission by Ce3+ ions. Following this energy‐transfer model, near‐UV convertible Eu3+‐activated red phosphors have been obtained in Ba2Y(BO3)2Cl: Ce3+, Tb3+, Eu3+ phosphors. Energy transfers from Ce3+ to Tb3+, and Tb3+ to Eu3+, as well as corresponding energy‐transfer efficiencies are investigated. The combination of narrow‐line red emission and near‐UV broadband excitation makes Ba2Y(BO3)2Cl: Ce3+, Tb3+, Eu3+ as a novel and efficient red phosphor for NUV LED applications.  相似文献   

14.
《Ceramics International》2015,41(6):7766-7772
A series of (1−x)YVO4/xY2O3:Eu3+0.006,Bi3+0.006 (0≤x≤0.54) composite phosphors was synthesized in one step by high temperature solid state reaction and the photoluminescence properties were investigated. By means of co-doping Eu3+ and Bi3+ ions into the composite matrices composed of YVO4 and Y2O3 crystals, the YVO4/Y2O3:Eu3+,Bi3+ phosphor exhibits simultaneously the blue (418 nm), green (540 nm) and orange-red (595, 620 nm) emissions. The broad blue and green emissions are attributed to the 3P11S0 transitions of Bi3+ ion both in Y2O3 and in YVO4 matrices. Moreover, the sharp orange-red emissions are attributed to the 5D07F1,2 transitions of Eu3+ ion in YVO4 matrix. By tuning the mole ratio of YVO4/Y2O3 matrices the white light-emitting could be obtained. The results indicated that when the mole ratio of Y2O3 (x) is at 0.11–0.54 mol, the (1−x)YVO4/xY2O3:Eu3+0.006,Bi3+0.006 phosphors emit white light by combining the blue, green and orange-red emissions under the excitation of 360–370 nm wavelength which matches the emission of the commercial UV-LED diode. This implies that the phosphors may be the promising white light materials with broad absorption band for white light-emitting diodes.  相似文献   

15.
《Ceramics International》2020,46(3):3264-3274
We report a change in the red photoluminescence of the Eu3+ doped Na2Sr2Al2PO4Cl9 phosphor via doping of singly, doubly and triply ionized ions. The synthesized phosphors show good crystalline nature. The EDS analysis confirms the presence of desired elements in the phosphor samples. The vibrational feature of the phosphor was confirmed by FTIR analysis. The photoluminescence excitation spectra of the phosphor show three peaks at 317, 395 and 467 nm. The Eu3+ doped Na2Sr2Al2PO4Cl9 phosphor emits intense red color on excitations with 395 and 467 nm wavelengths. However, the photoluminescence intensity of the phosphor is larger for 395 nm excitation. When the singly, doubly and triply ionized ions are co-doped in the Eu3+ doped Na2Sr2Al2PO4Cl9 phosphor (i.e. F, WO42−, MoO42−, VO43−, La3+, and Y3+) the photoluminescence intensity of the phosphor is decreased significantly. The decrease in photoluminescence intensity is due to change in local crystal structure created by these ions. Interestingly, the photoluminescence intensity of phosphor increases many times when the (Y3+) ion incorporated phosphor is excited with 317 nm wavelength. The CIE diagram shows color emitted in the red region of visible spectrum and the color purity is larger for triply ionized (Y3+) ion. Thus, the singly, doubly and triply ionized ions activated Na2Sr2Al2PO4Cl9: Eu3+ phosphor may be used in displays devices, photonic devices, solid state lighting and white LEDs.  相似文献   

16.
In this paper, Ba3P4O13:Eu2+ phosphor was synthesized by a solid-state reaction. The photoluminescence (PL) emission spectrum and luminescence decay kinetics confirm that the doped Eu2+ ions can occupy two different Ba2+ sites. The PL excitation spectrum shows a broad band matching well with the emission of near-UV chip. Ba3P4O13:Eu2+ is a promising phosphor for near-UV chip excited white LEDs. The doped Eu3+ ions can also be reduced to Eu2+ ions in air atmosphere at high temperature. Charge compensation mechanism is applied to explain this kind of abnormal reduction.  相似文献   

17.
A series of Ca5(PO4)3F:Dy3+, Eu3+ phosphors was synthesized by a solid‐state reaction method. The XRD results show that all as‐prepared Ca5(PO4)3F:Dy3+, Eu3+ samples match well with the standard Ca5(PO4)3F structure and the doped Dy3+ and Eu3+ ions have no effect on the crystal structure. Under near‐ultraviolet excitation, Dy3+ doped Ca5(PO4)3F phosphor shows blue (486 nm) and yellow (579 nm) emissions, which correspond to 4F9/26H15/2 and 4F9/26H13/2 transitions respectively. Eu3+ co‐doped Ca5(PO4)3F:Dy3+ phosphor shows the additional red emission of Eu3+ at 631 nm, and an improved color rendering index. The chromaticity coordinates of Ca5(PO4)3F:Dy3+, Eu3+ phosphors also indicate the excellent warm white emission characteristics and low correlated color temperature. Overall, these results suggest that the Ca5(PO4)3F:Dy3+, Eu3+ phosphors have potential applications in warm white light‐emitting diodes as single‐component phosphor.  相似文献   

18.
A green Y5(SiO4)3N:Eu2+ phosphor has been successfully prepared by developing a new SiC reduction‐assisted sol–gel method. The valence state of Eu ions was identified with XPS analysis and the photoluminescence spectrum presents a Eu2+ typical broad green emission band. XRD analysis, photoluminescence and excitation measurement, and FTIR test were also carried out, to obtain crystal phase, light emitting, and chemical bonding results. The specific mechanism of SiC reductant in the synthetic process was studied in details. This novel method shows lower equipment requirements and is cost saving. The method can extend applications in synthesizing other silicon‐based oxynitrides.  相似文献   

19.
《Ceramics International》2016,42(6):6891-6898
A series of single-phase white-light-emitting phosphors, Eu2+-activated Ba3GdNa(PO4)3F phosphors were synthesized by solid-state reactions. The crystal structure of Ba3GdNa(PO4)3F was been identified by Rietveld refinement of X-ray diffraction pattern. The Eu2+-activated Ba3GdNa(PO4)3F phosphors exhibit broad excitation spectra from 250 to 420 nm, which matched well with the n-UV LED chips. Under the excitation of 365 nm, the emission spectrum almost covered the entire visible region including two emission bands peaked at 472 nm and 640 nm. Three different Eu2+ emission centers in Ba3GdNa(PO4)3F:Eu2+ phosphor were confirmed by their fluorescence decay lifetimes. The optimal concentration of Eu2+ in Ba3GdNa(PO4)3F:xEu2+ was 3 mol% and the corresponding concentration quenching mechanism was verified to be exchange coupling interaction. Furthermore, the white light-emitting diode fabricated with Ba3GdNa(PO4)3F:0.05Eu2+ phosphor and a 370 nm UV chip has a CIE of (0.3267, 0.2976) with a color-rendering index of 78.4 at the CCT of 5287 K.  相似文献   

20.
《Ceramics International》2022,48(2):1560-1566
The development of highly stable and efficient oxide-based red phosphors is urgently required for next-generation lighting devices. Herein, we report the micro/crystal structures and luminescent properties of single-phase Eu2(WO4)3 and Eu3+-doped WO3-Eu2(WO4)3 composite phosphors prepared by a one-step conventional solid-state reaction method in air atmosphere. As increasing Eu contents in the mixtures of WO3 and Eu2O3, the intensities of the X-ray diffraction peaks of Eu2(WO4)3 increased while that of WO3 decreased. The photoluminescence intensity of the synthesized phosphors increased with increase in the Eu content when calcined at 900 °C, while it degraded at a higher temperature. Red-emitting single-phase Eu2(WO4)3 powders were successfully obtained when the WO3 and Eu2O3 powders were calcined in the ratio of 3:1. The intensity of the red emission spectra of the Eu2(WO4)3 phosphor was higher than those of the 6, 12, and 24 at.% Eu-added WO3 composites at excitation wavelengths of 394 and 465 nm. On the other hand, the intensity of emission from the single-phase phosphor was lower than that of the Eu-doped WO3-Eu2(WO4)3 composites under excitation of UV light at 254 nm. Thus, we propose two prospective phosphors for application as red phosphors at various wavelengths.  相似文献   

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