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1.
Eu3+ ion doped chlorophosphate glass ceramics containing nanocrystals were successfully prepared, and their spectroscopic characterizations were done using absorption, excitation and emission spectra. For the crystallized samples, X-ray diffraction (XRD) and transmission electron microscopy (TEM) experiments evidenced the formation of CaCl2 nanocrystals. The absorption and emission spectra investigations indicate that a considerable amount of Eu3+ ions was trapped in CaCl2 nanocrystals, and therefore an efficient up- and down-frequency conversion was observed. The comparative spectroscopic studies of Eu3+ doped samples suggest that the investigated glass ceramics systems are potentially applicable as frequency-conversion photonics devices.  相似文献   

2.
The nanocrystal samples of titanium dioxide doped with europium ion (Eu3+/TiO2 nanocrystal) are synthesized by the sol-gel method with hydrothermal treatment. The Eu3+ contents (molar ratio) in the samples are 0, 0.5%, 1%, 2%, 3% and 4%. The X-ray diffraction, UV-Vis spectroscopy data and scanning electron microscope image show that crystallite size is reduced by the doping of Eu3+ into TiO2. Comparing the Raman spectra of TiO2 with Eu3+/TiO2 (molar ratio Eu3+/TiO2=1%, 2% and 4%) nanocrystals at different annealing temperatures indicates that the anatase-to-rutile phase transformation temperatures of Eu3+/TiO2 nanocrystals are higher than that of TiO2. This is due to the formation of Eu-O-Ti bonds on the surface of the TiO2 crystallite, as characterized by the X-ray photoelectron spectroscopy. The photoluminescence spectra of TiO2 in Eu3+/TiO2 nanocrystals are interpreted by the surface self-trapped and defect-trapped exciton relaxation. The photoluminescence of Eu3+ in Eu3+/TiO2 nanocrystals has the strongest emission intensity at 2% of Eu3+ concentration.  相似文献   

3.
A red-emitting phosphor of Eu3+-doped calcium–tellurium–zinc oxide, Ca3Te2(ZnO4)3, with a garnet-type structure was synthesized by high temperature solid-state reactions. This phosphor exhibited a strong red emission. The photoluminescence excitation spectrum showed that Ca3Te2(ZnO4)3:Eu3+ can be effectively excited by UV–visible light. The property of long-wavelength excitation for this material has a benefit as a red phosphor in application of white light-emitting diodes. The colour coordinates were calculated. The excitation and emission spectra and luminescence decay curves were obtained using a pulsed, tunable, narrowband dye laser. Crystallographic sites and charge compensation mechanism of Eu3+ ions were discussed. The emission line from Eu3+ in intrinsic crystallographic site in the lattice was located at 579.56 nm. The emission line from Eu3+ in another disturbed site, which is created by the defects created by the charge-compensation, was located at 580.88 nm. The disordered crystallographic sites of Eu3+ are benefit for their strong red luminescence corresponding to the 5D07F2 transition.  相似文献   

4.
Photoluminescence, absorption and optical excitation spectra of undoped and Eu3+-doped binary zinc borate glasses of varied composition prepared by the melt quenching technique in air atmosphere were investigated. From photoluminescence measurements it was found that growing Eu3+ concentration leads to gradual disappearance of the broadband glass emission in the near-UV spectral range, while the red Eu3+ emission at 613 nm shows a considerable increase. This result together with excitation spectra suggests that the Eu3+ ions are excited via energy transfer from the initially excited glassy host. The glass composition strongly affects the position of the excitation maximum in the UV energy range.  相似文献   

5.
Structural and optical properties of nanopowders of Eu3+-doped LiLaP4O12 (LiLaPO) were studied. The samples were synthetized via polyvinyl alcohol assisted sol gel method. Powder X-ray diffraction (XRD) results showed that the samples have the LiLaPO crystalline phase and scanning electron microscopy (SEM) showed that the particles are in the nanometer scale, mostly as isolated particles with same aggregates. Photoluminescence (PL) properties were evaluated via excitation and emission spectra. The excitation spectra, in the range 2.6–13.8 eV, allowed the identification of the charge transfer band, 4f → 4f5d excitation, exciton formation and the interband excitation of the Eu3+ ions in the matrix. The emission spectra revealed that Eu3+ is located in two different sites in the samples, one of them being at the bulk and the other close to the surface of the nanoparticles, result confirmed by the CT excitation band.  相似文献   

6.
Aluminate phosphors SrMgAl10O17 codoped with Eu2+ and Mn2+ ions were prepared by solid-state reaction. The phase structure and photoluminescence properties of the as-prepared phosphors were characterized by powder X-ray diffraction, photoluminescence excitation and emission spectra. Upon excitation of UV light, two broad emission bands centered at 470 and 515 nm were observed, and they were assigned to Eu2+ and Mn2+ emissions, respectively. The emission color of the phosphors can be tuned from blue to cyan and finally to green by adjusting the concentration ratios of Eu2+ and Mn2+. Effective energy transfer occurs from Eu2+ to Mn2+ in the host due to the spectral overlap between the emission band of Eu2+ and the excitation bands of Mn2+. The energy transfer mechanism was demonstrated to be electric dipole–quadrupole interaction. The energy transfer efficiency and critical distance were also calculated. The phosphors exhibit strong absorption in near UV spectral region and therefore they are potentially useful as UV-convertible phosphors for white LEDs.  相似文献   

7.
BaMg2Al6Si9O30:Eu2+ phosphors are synthesized by the solid-state reaction method and their photoluminescence (PL) properties are investigated. The ultraviolet emission originates from Eu2+(I) substituting for Ba2+ sites, whereas the blue emission is attributed to Eu2+(II) substituting for Mg2+ sites. With increasing Eu2+ doping concentrations, the blue emission band shifts to long wavelength and the PL intensity ratio of blue to ultraviolet emission increases. Energy transfer between the two different Eu2+ ions is analyzed by photoluminescence excitation and emission spectra, and lifetimes. Results indicate that the emission spectra can be tuned by changing Eu2+ contents. We have also demonstrated that BaMg2Al6Si9O30:Eu2+ phosphor is a kind of potential phosphor for fluorescent lamps.  相似文献   

8.
Nanocrystalline powders with various Eu3+ concentration (from 1 to 10 mol %) doped La2O3 were prepared via a combustion route. Their structure and morphology were characterized using X-ray diffraction (XRD) and High-resolution transmission electron microscopy. The emission spectra of the as-synthesized samples show that the strongest emission position is centered at 626 nm corresponding to 5D07F2 transition of Eu3+ ions and the intensity change of 626 nm emission is considered as a function of ultraviolet (240 nm) irradiation time. The excitation spectra at 626 nm monitoring indicate that the charge transfer state band is varies with different Eu3+ ion concentration. These results are attributed to the surface defects of the nanocrystals.  相似文献   

9.
We have used the Bridgman method to grow CsBr:Eu2+ single crystals, adding an activator to the mix in the form of Eu2O3 in amounts of 0.0125, 0.0250, and 0.0500 mole %. At T = 300 K, we studied the absorption spectra, the photoluminescence (PL) spectra, and the photostimulated luminescence (PSL) spectra of the grown crystals. We have established that the structure of the photoluminescence and photostimulated luminescence centers in crystals grown from the CsBr:Eu2O3 mix includes isolated dipole centers Eu2+-VCs, emitting in bands with maxima at 432 nm and 455 nm respectively, and in crystals grown at activator concentrations of 0.025 and 0.050 mole % they also include aggregate centers (AC) based on CsEuBr3 nanocrystals with emission bands at 515 m and 523 nm. We have shown that the maximum concentration of aggregate centers of the CsEuBr3 nanocrystal type in CsBr:Eu2+ crystals is achieved for an activator content in the mix within the range 0.01–0.05 mole %. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 359–362, May–June, 2006.  相似文献   

10.
Eu2+激活的Ca3SiO5绿色荧光粉的制备和发光特性研究   总被引:3,自引:0,他引:3       下载免费PDF全文
杨志平  刘玉峰 《物理学报》2006,55(9):4946-4950
研究了Eu2+激活的绿色发光材料Ca3SiO5的制备条件和发光性质. Eu2+中心形成主峰值为501 nm和次峰值为570 nm的特征宽带,两峰值叠加形成发射峰值为502nm的绿色发射光谱带. 利用这些光谱结果和Van Uitert 经验公式,确认Ca3SiO5:Eu2+中存在两种性质有差异的Eu2+发光中心,它们分别占据基质中八配位的Ca2+(Ⅰ)格位和四配位的Ca2+(Ⅱ)格位. 其激发光谱分布在250—450 nm的波长范围,峰值位于375 nm处,可以被InGaN管芯产生的350—410 nm辐射有效激发. 关键词: 发光 荧光粉 绿色荧光粉 3SiO5')" href="#">Ca3SiO5 2+')" href="#">Eu2+  相似文献   

11.
Blue-emitting Li4SrCa(SiO4)2:Eu2+ phosphors have been synthesized by solid-state reaction. The photoluminescence (PL) excitation spectrum shows broad-band absorption and matches well with the emission of a near-UV (n-UV) chip. The PL emission spectrum exhibits a broad-band emission peaking at 430 nm, which is the characteristic emission of the f–d transition of the Eu2+ ion. The diffuse reflection spectra, temperature-dependent emission spectra, fluorescence decay, and mechanism of concentration quenching are also studied in detail. Li4SrCa(SiO4)2:Eu2+ is a candidate blue phosphor for n-UV excited solid-state lighting.  相似文献   

12.
Vacuum ultraviolet (VUV) excitation and photoluminescence (PL) properties of Sr(Y, Gd)2O4 doped with Eu3+ were studied. The excitation spectra of SrY1.9Eu0.1O4 and SrY1.0Gd0.9Eu0.1O4 had absorption in the VUV region with the absorption band edge at 149 nm, while the absorption of SrGd1.9Eu0.1O4 in the VUV region was weak, which could be due to the narrow host band gap and no efficient energy transfer occurred in the VUV region. The PL spectra of all samples exhibited the characteristic emission of Eu3+ with the red 5D0-7F2 transition (611 nm) being the most prominent group.  相似文献   

13.
Ca2GeO4:Eu3+ phosphors were synthesized by the solid state method. The ultraviolet and vacuum ultraviolet excited photoluminescence properties were investigated in detail. It revealed that the emission of Ca2GeO4:Eu3+ comprised two parts: the red emission of Eu3+ and host defect emission in 330-550 nm. Ca2GeO4:Eu3+ presented intense excitation intensity at 163-200 and 466 nm, which suggested the potential applications in plasma display panels and light emitting diodes. The excitation spectra were studied to identify the photoluminescence mechanisms of Ca2GeO4:Eu3+. First principles calculation within the local density approximation of the density functional theory was applied to calculate the electronic structure and linear optical properties of Ca2GeO4.  相似文献   

14.
Eu2+ and Mn2+ co-activated Sr5(PO4)3Cl phosphors with blue and orange color double emission bands, under a broad-band excitation wavelength range of 340–400 nm, were synthesized by the solid-state reaction. It was found that the processing parameters, including the fluxes, annealing time and activators concentrations, affect the emission intensity and other luminescent properties. Energy transfer between Eu2+ and Mn2+ was discovered and the transfer efficiency was also estimated based on relative intensities of Eu2+ and Mn2+ emission. Thus the relative strength of blue and orange emission intensities could be tuned by varying the relative concentration of Eu2+ and Mn2+. Since the photoluminescence excitation spectra of the newly developed Sr5(PO4)3Cl:Eu2+, Mn2+ phosphors exhibit a strong absorption in the range of 340–400 nm, they are promising for producing UV-LED-based white LEDs.  相似文献   

15.
Eu2+:CeBr3 crystals were grown by vertical Bridgman growth method and slight aliovalent doping of Eu2+ in the CeBr3 crystal did not change the crystal structure. The X-ray stimulated luminescence, photoluminescence, decay kinetics and scintillation properties were investigated at room temperature. The X-ray stimulated luminescence spectra exhibited wide broad emission bands from 3.54 eV to 2.95 eV in the Eu2+:CeBr3 crystal with high content of 620 ppm of Eu2+, which were the overlap of the emission bands ascribed to 5d → 4f transition of Ce3+ and 4f65 d1 → 4f7 transition of Eu2+, respectively. When the content of Eu2+ was decreased to 70 ppm, another emission band centered at 2.29 eV was observed. The photoluminescence spectra showed the energy transfer from Ce3+ to Eu2+. This decreased the Ce3+ emission intensity but enhanced the Eu2+ emission intensity. The photoluminescence decay time of Ce3+ emission decreased from 14 ns to 10 ns when the content of Eu2+ increased from 70 ppm to 620 ppm. The decay time of the emission of 525 nm did not change with the excitation wavelength and Eu2+ content, which could be assigned to the excitons that were bound on Eu2+ related centers. The light output of the Eu:CeBr3 crystal under the excitation of 241Am radioactive source was less than 20.2% of Tl:NaI crystal.  相似文献   

16.
The emission and excitation spectra of Gd2SiO5∶Eu3+ were investigated using the VUV beam line of the Beijing Synchrotron Radiation Facility (BSRF). The experimental results were discussed in the frame of visible quantum cutting process involved in Gd3+−Eu3+ system. Upon direct excitation into the6G J states of Gd3+, two visible photon emissions from Eu3+ were observed. Cursory evaluation proved that Gd2SiO5∶Eu3+ is an efficient visible quantum cutter.  相似文献   

17.
Powder samples of NaMgPO4 doped with Eu2+ and Ce3+ were prepared and their photoluminescence spectra were systemically studied. Energy transfer from Ce3+ to Eu2+ in NaMgPO4 phosphor was observed by investigating the optical properties from photoluminescence spectra in Eu2+ or Ce3+ singly doped and Eu2+–Ce3+ codoped sodium magnesium orthophosphates, NaMgPO4. The enhancement of UV excitation is attributed to energy transfer from Ce3+ to Eu2+, and Ce3+ plays a role as a sensitizer. Ce3+–Eu2+ codoped NaMgPO4 phosphors in which Eu2+ can be efficiently excited by 390 nm are potential candidates for phosphor-converted LEDs.  相似文献   

18.
The opal-Lu1.86Eu0.14O3 composites have been prepared using the developed technique for synthesizing luminophor nanocrystals in pores of synthetic opal through coprecipitation from a solution. It has been demonstrated that the position of the photonic stop band in the reflection spectrum of the infiltrated opal depends on the diameter of its spheres, the volume fraction of the embedded luminophor, and the angle of detection of the signal. The excitation and photoluminescence spectra of the composites have been analyzed, and the lifetime of the 5 D 0 excited state of Eu3+ ions has been examined. It has been revealed that the luminescence decay time for the luminophor increases by almost one order of magnitude with an increase in its content in opal pores. This effect has been attributed to the change in the nanocrystal size and to the decrease in the contribution from the surface nonradiative recombination in luminophor nanolayers of the composites.  相似文献   

19.
Eu2+-activated Sr2LiSiO4F phosphors were synthesized at 900°C by solid-state reaction in reducing atmosphere, and their photoluminescence (PL) properties were systematically investigated by diffuse reflection spectra, PL excitation and emission spectra, and by the fluorescence decay curve. Sr2LiSiO4F:Eu2+ emits intense green light at 520 nm originating from the 5d14f6−4f7 transition of Eu2+ under 365 nm n-UV excitation. The PL excitation spectrum matches the emission from n-UV chips. These materials could be promising green phosphors for use in generating white light in phosphor-converted white light-emitting-diodes (LEDs).  相似文献   

20.
Vacuum ultraviolet (VUV) excitation and photoluminescence (PL) characteristics of Eu3+ ion doped borate phosphors; BaZr(BO3)2:Eu3+ and SrAl2B2O7:Eu3+ are studied. The excitation spectra show strong absorption in the VUV region with the absorption band edge at ca. 200 nm for BaZr(BO3)2:Eu3+ and 183 nm for SrAl2B2O7:Eu3+, respectively, which ensures the efficient absorption of the Xe plasma emission lines. In BaZr(BO3)2:Eu3+, the charge transfer band of Eu3+ does not appear strongly in the excitation spectrum, which can be enhanced by co-doping Al3+ ion into the BaZr(BO3)2 lattices. The luminescence intensity of BaZr(BO3)2:Eu3+ is also increased by Al3+ incorporation into the lattices. The PL spectra show the strongest emission at 615 nm corresponding to the electric dipole 5D07F2 transition of Eu3+ in both BaZr(BO3)2 and SrAl2B2O7, similar to that in YAl3(BO3)4, which results in a good color purity for display applications.  相似文献   

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