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1.
Eu2+ and Mn2+ singly doped and codoped Na(Sr,Ba)PO4 phosphors were synthesized, and their luminescent properties were investigated. A broad blue emission and a broad orange emission band were observed in Na(Sr,Ba)PO4:Eu2+, Mn2+ phosphor. The resonant-type energy transfer from Eu2+ to Mn2+ was demonstrated, and the energy transfer efficiency was also calculated according to their emission spectra. Based on the principle of energy transfer, the emission intensity ration of Eu2+ and Mn2+ could be appropriately tuned by adjusting the contents of activators. Due to the strong absorption in the 250–400 nm range, Na(Sr,Ba)PO4:Eu2+, Mn2+ phosphor could be used as a potential candidate for near-UV white light-emitting diodes (LEDs).  相似文献   

2.
A novel long-lasting phosphorescence phosphor, Mn2+-activated Mg2SnO4, has been synthesized and its optical properties have been investigated. The Mg2SnO4:Mn2+ emits green light with high luminance, upon UV irradiation, centered at 499 nm from the spin forbidden transitions of the d-electrons in Mn2+ ions. The CIE chromaticity coordinates of the Mg2SnO4:Mn2+ phosphor are x=0.0875 and y=0.6083 under 254 nm UV excitation. The phosphorescence can be observed by the naked eyes (0.32 mcd/m2) in the dark clearly for over 5 h after the 5 min UV irradiation. Thermoluminescence has been studied and the mechanism of the long-lasting phosphorescence has been discussed.  相似文献   

3.
Zn2?2x Mn2x GeO4 (x=0, 0.001, 0.01) phosphors were prepared by conventional solid state reaction technique. X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), diffuse reflection spectra, photoluminescence (PL), and cathodoluminescence (CL) spectroscopy were utilized to characterize the synthesized phosphors. The Mn2+-activated Zn2GeO4 phosphors exhibit narrow emission band at 532 nm under the excitation of ultraviolet light, which due to the 4T1(4G)–6A1(6S) transition of Mn2+ ions. Also it is observed that there exists energy transfer between the Zn2GeO4 host lattice and the activator (Mn2+). Under excitation of low-voltage electron beams, Zn2GeO4:Mn2+ shows strong green emission band dominating at 535 nm, corresponding to the 4T1(4G)–6A1(6S) emission of Mn2+ ions. The emission intensity and chromaticity coordinates of Zn2GeO4:Mn2+ as a function of accelerating voltage and the filament current were also investigated.  相似文献   

4.
Changyu Shen  Yi Yang  Huajun Feng 《Optik》2010,121(1):29-32
The shift of the emission band to longer wavelength (yellow-orange) of the Ba2MgSi2−xAlxO7: 0.1Eu2+ phosphor under the 350-450 nm excitation range has been achieved by adding the codoping element (Mn2+) in the host. The single-host silicate phosphor for WLED, Ba2MgSi2−xAlxO7: 0.1Eu2+, 0.1Mn2+ was prepared by high-temperature solid-state reaction. It was found experimentally that, its three-color emission peaks are situated at 623, 501 and 438 nm, respectively, under excitation of 350-450 nm irradiation. The emission peaks at 438 and 501 nm originate from the transition 5d to 4f of Eu2+ ions that occupy the two Ba2+ sites in the crystal of Ba2MgSi2−x AlxO7, while the 623 nm emission is attributed to the energy transfer from Eu2+ ions to Mn2+ ions. The white light can be obtained by mixing the three emission colors of blue (438 nm), green (501 nm) and red (623 nm) in the single host. When the concentrations of the Al3+, Eu2+ and Mn2+ ions were 0.4, 0.1 and 0.1 mol, respectively, the sample presented intense white emission. The addition of Al ion to the host leads to a substantial change of intensity ratio between blue and green emissions. White light could be obtained by combining this phosphor with 405 nm light-emitting diodes. The near-ultraviolet GaN-based Ba2MgSi1.7 Al0.3O7: 0.1Eu2+, 0.1Mn2+ LED achieves good color rendering of over 85.  相似文献   

5.
A long-lasting phosphor Ca0.2Zn0.9Mg0.9Si2O6:Eu2+, Dy3+, Mn2+ was prepared by a sol-gel method. Nanoparticles crystallizing in a clinoenstatite structure were obtained. Long persistent phosphorescence in the red has been observed with persistence time over one hour at 680 nm and was attributed to Mn2+ emission. The persistent luminescence is suggested to involve Eu2+ as a sensitizer, Dy3+ or Dy3+-related defect as a trap center and Mn2+ as the luminescent center. However, the details of the mechanism are still under further investigation.  相似文献   

6.
A novel red phosphor La2MgTiO6:xEu3+ was successfully synthesized by the conventional solid state method. Excited by ultraviolet (395 nm) and blue (465 nm) light, La2MgTiO6:xEu3+ exhibits intense red emission. Due to the lack of inversion symmetry at the doping sites, the dominant emission peak is from the transition 5D07F2. Non-radiative transitions were demonstrated to be from dipole–dipole interactions and the critical distance was estimated to be ~9.19 Å. When Eu3+ ions' concentration reaches 15%, the emission intensity is about three times higher than that of the conventional phosphor Y2O3:Eu3+. The Commission International de L'Eclairage chromaticity coordinate was calculated to be x=0.657 and y=0.343. All the results indicate that La2MgTiO6:xEu3+ has superior luminescence properties.  相似文献   

7.
LaMgAl11O19 phosphor doped with Eu and Mn ions has been prepared by the urea combustion route. The as-prepared phosphor was studied using X-ray diffraction, electron paramagnetic resonance (EPR), diffuse reflectance and photoluminescence studies. The EPR spectra of LaMgAl11O19:Eu, Mn phosphor exhibit signals with the effective g values at g = 1.98, 4.29 and 7.23. The resonance signals at g = 1.98 and 4.29 were attributed to Mn2+ ions in tetrahedral and rhombic environment, respectively. The resonance signal at g = 7.23 was attributed to Eu2+ ions. The optical spectrum of this phosphor exhibits an intense band in the visible region and this band has been attributed to spin-allowed 5Eg → 5T2g transition of Mn3+ ions. Upon excitation at 324 nm, the material displays emission in the blue, green and red spectral region.  相似文献   

8.
The BaGd2?x O4:xDy3+ (0 ≤ x ≤ 0.08) phosphors were synthesized at 1,300 °C in air by the solid-state reaction route. The as-synthesized phosphors were characterized by X-ray powder diffraction, photoluminescence excitation spectra, photoluminescence (PL) spectra, X-ray excited luminescence (XEL) spectra, and thermoluminescence (TL) spectra. It is found that the quenching concentration of Dy3+ ions in BaGd2O4 host is dependent on the selected excitation wavelength. The optimal PL intensity for the investigated BaGd2?x O4:xDy3+ phosphors is found to be x = 0.01, 0.02, and 0.04, upon excitation by 234, 277, and 350 nm ultraviolet light, respectively. The energy transfer among Dy3+ ions upon excitation by 350 nm is confirmed to be an electric dipole–dipole interaction mechanism based on the fitting of Huang’s rule. In addition, the intensive XEL from BaGd2O4:Dy3+ phosphor is observed by the naked eyes at room temperature, and TL properties of the investigated phosphors are analyzed and discussed. All the results imply that the investigated phosphors could be a promising scintillating phosphor.  相似文献   

9.
The (Ca1−x,Srx)S:Eu2+ red-emitting phosphors were prepared by using sulfide and sulfate in CO-reductive atmosphere, respectively, and their luminescent properties have been investigated. The XRD data showed that the doping of divalent Europium ion (Eu2+) enlarges the lattice parameters, and Sr/Ca ratio not only affects the lattice parameters, but also influences the emission peak. The excitation and emission spectra indicated that this phosphor can be effectively excited by visible light from 430 to 500 nm, and exhibits a satisfactory red performance. The annealing treatment process was also discussed in detail. Compared with the commercial afterglow sulfide phosphor, the present synthesized phosphor has higher emission efficiency and is a favorable choice for white light-emitting diode (LED). The white LED implanted by present phosphor shows desirable luminescence and chromaticity properties.  相似文献   

10.
Red long-lasting phosphor Y2O2S:Eu3+, Zn2+, Ti4+ nanotubes were prepared by hydrothermal method. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence and thermoluminescence spectra (TL) were used to characterize the long-lasting phosphor. XRD investigation revealed that the product synthesised under 750 °C for 6 h was a pure phase of Y2O2S. SEM observation showed that the sulfuretted phosphor inherited the tube-like shape from the precursor. Under 325 nm UV excitation, the result indicated the strongest red-emission lines at 627 nm, corresponded to the transition from 5D0 to 7F2 level of Eu3+ ion. Both the afterglow decay curves and TL curves revealed that the phosphor had efficient luminescent and excellent long-lasting properties.  相似文献   

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