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1.
《Current Applied Physics》2010,10(2):596-600
The spectroscopic and host phase properties of SrAl2O4:Eu2+, Dy3+ phosphors with a series of different initiating combustion temperature, urea concentration as a fuel and critical pH of precursor solution are investigated. The SrAl2O4:Eu2+, Dy3+ nanoparticle pigments were obtained by exothermic combustion process within less than 5 min. The sample that ignited at initiating combustion temperature of 600 °C exhibits highest intensity emission peak at 517 nm in which the SrAl2O4 host phase has the maximum fraction of monoclinic SrAl2O4 phase. The excitation spectra consist of 240 and 254 nm broad peaks. The experimental results show that the optimum ratio of urea is 2.5 times higher than theoretical quantities for best emission condition of SrAl2O4:Eu2+, Dy3+ phosphor particles. The critical pH was obtained about 5.2. The crystallite size of these pigments is about 40 nm before thermal treatment and 62 nm after thermal treatment, respectively. 相似文献
2.
By using metal nitrates as starting materials, SrAl2B2O7: Tb3+ and SrAl2B2O7: Ce3+, Tb3+ powder phosphors were prepared by sol-gel method. X-ray diffraction (XRD), photoluminescence excitation and emission, as well as kinetic decays were employed to characterize the resulting samples. The results show that energy transfers from Ce3+ to Tb3+ ions. The emission intensity of Tb3+ ions in SrAl2B2O7 could be greatly intensified when Ce3+ ions are doped into SrAl2B2O7: Tb3+. The decay times of SrAl2B2O7: Tb3+ were prolonged when Ce3+ ions were doped. The doping of Ce3+ ions not only improved the luminescent intensity, but also made the materials gets stable luminescent properties. 相似文献
3.
Hua Yu Degang Deng Shiqing Xu Cuiping Yu Haoyong Yin QiuLin Nie 《Journal of luminescence》2012,132(10):2553-2556
An Eu2+-activated oxynitride LiSr(4?y)B3O(9?3x/2)Nx:yEu2+ red-emitting phosphor was synthesized by solid-state reactions. The synthesized phosphor crystallized in a cubic system with space group Ia–3d. The LiSr4B3O(9?3x/2)Nx:Eu2+ phosphors exhibited a broad red emission band with a peak at 610 nm and a full width at half maximum of 106 nm under 410 nm excitation, which is ascribed to the 4f65d1→4f7 transition of Eu2+. The optimal doped nitrogen concentration was observed to be x=0.75. The average decay times of two different emission centers were estimated to be 568 and 489 ns in the LiSr3.99B3O8.25N0.5:0.01Eu2+ phosphors, respectively. Concentration quenching of Eu2+ ions occurred at y=0.07, and the critical distance was determined as 17.86 Å. The non-radiative transitions via dipole–dipole interactions resulted in the concentration quenching of Eu2+-site emission centers in the LiSr4B3O9 host. These results indicate LiSr4B3O(9?3x/2)Nx:Eu2+ phosphor is promising for application in white near-UV LEDs. 相似文献
4.
Zhendong Hao Jiahua Zhang Xia Zhang Shaozhe Lu Yongshi Luo Xinguang Ren Xiaojun Wang 《Journal of luminescence》2008,128(5-6):941-944
α- and β-Ca2P2O7: Eu2+, Mn2+ phosphors were prepared by solid-state reaction. Phase transition from tetragonal (β-phase) to monoclinic (α-phase) is performed. A strong orange emission of Mn2+ is observed in both α-and β-Ca2P2O7: Eu2+, Mn2+ upon near ultraviolet (UV) excitation through energy transfer from Eu2+ to Mn2+. The transfer efficiencies for various Mn2+ concentrations are estimated based on lifetime measurements of the fluorescence of Eu2+ in the two phases. The photoluminescence excitation spectra of α-Ca2P2O7: Eu2+, Mn2+ can cover 400 nm of the near-UV range, denoting its potential use as a phosphor with intense orange component for white light emitting diodes (LEDs). 相似文献
5.
Two series of calcium gallate phosphors: Ca1?xEuxGa4O7 and Ca1?2xEuxNaxGa4O7 (x=0, 0.002, 0.01, 0.02, 0.03, 0.05) were synthesized by a modified Pechini method and their optical properties at 298 and 77 K were investigated. In undoped CaGa4O7 upon 255 nm excitation a bluish white emission (λmax=500 nm) followed by an afterglow of the same color lasting for 10–20 s was observed. Eu3+-doping quenched the host-related luminescence and the characteristic red emission of the dopant with maximum at 613 nm appeared. Its excitation spectrum consisted of a broad band assigned to ligand to metal, O2?→Eu3+, charge transfer absorption and narrow lines arising from intraconfigurational transitions within the 4f6 states of Eu3+ ion. The effects of Eu3+ concentration and Na+ co-doping on the luminescence properties and decay kinetics were studied. Low temperature emission spectra showed that Eu3+ ions are positioned in environments of different symmetries. Their relative populations changed with the activator content. Co-doping with Na+ ions led to a remarkable reduction of the number of Eu3+ sites as well as to noticeable improvement of the luminescence brightness though it did not affect the decay time of the emission. The quantum efficiencies of singly doped CaGa4O7:Eu3+ were very low (in the range of 1–3.7%). Na+ co-doping improved this parameter leading to the highest efficiency of 11% for CaGa4O7:3%Eu3+,3%Na+. 相似文献
6.
Bento F. dos Santos Marcos V. dos Santos Rezende Paulo J.R. Montes Romel M. Araujo Marcos A.C. dos Santos Mário E.G. Valerio 《Journal of luminescence》2012,132(4):1015-1020
Computational and experimental method is employed to study optical properties SrAl2O4 induced by europium dopant. Atomistic modeling is used to predict the doping sites and charge-compensation schemes for SrAl2O4:Eu systems and also to calculate the symmetry and the detailed geometry of the dopant site. This information is then used to calculate the crystal field parameters. SrAl2O4 doped with europium were prepared via a sol–gel proteic methodology. The photoluminescence experiments were performed at room temperature and at 13 K. The transition energy for the Eu3+-doped material is compared to the theoretical results. Based on Judd-Ofelt approach, the intensity parameters Ω2,4 of Eu3+ in the SrAl2O4 matrix were calculated. 相似文献
7.
Jiayue Sun Yining Sun Jinli Lai Zhiguo Xia Haiyan Du 《Journal of luminescence》2012,132(11):3048-3052
Ce3+ and Tb3+ co-doped BaAl2B2O7 phosphors were synthesized by the solid-state method. X-ray diffraction (XRD) was used to characterize the phase structure. The photoluminescent properties of Ce3+ and Tb3+ co-doped BaAl2B2O7 phosphors were investigated by using the photoluminescence emission and excitation spectra. Under the excitation of near ultraviolet (n-UV) light, BaAl2B2O7:Ce3+,Tb3+ phosphors exhibited blue emission corresponding to the f–d transition of Ce3+ ions and green emission bands corresponding to the f–f transition of Tb3+ ions, respectively. Effective energy transfer occurred from Ce3+ to Tb3+ in BaAl2B2O7 host due to the observed spectra overlap between the emission spectrum of Ce3+ ion and the excitation spectrum of Tb3+ ion. The energy transfer efficiency from Ce3+ ion to Tb3+ ion was also calculated to be 71%. Furthermore, the concentration quenching and critical distance of BaAl2B2O7:Ce3+,Tb3+ phosphors were also discussed. The energy transfer from Ce3+ to Tb3+ in BaAl2B2O7 host was demonstrated to be resonant type via a dipole–dipole interaction mechanism with the energy transfer critical distance of 16.13 Å. 相似文献
8.
Mingxing Ma Dachuan Zhu Cong Zhao Tao Han Shixiu Cao Mingjing Tu 《Optics Communications》2012,285(5):665-668
Sr2+ doped BaAl2Si2O8:Eu2+ phosphor was synthesized by chemical co-precipitation method. With the increase of Sr2+ concentration, the phase structure of (Ba0.965 ? xSrxEu0.035)Al2Si2O8 changes from hexagonal phase to monoclinic phase owing to large activation energy in SrAl2Si2O8 system. (Ba0.965 ? xSrxEu0.035)Al2Si2O8 phosphor exhibits a broad blue band peaking at 425 nm due to the 4f65d–4f7(8S7/2) transition of Eu2+ ions. The emission intensity increases, accompanied by the blue shift of emission maximum from 459 to 417 nm with the Sr2+ doping concentration increasing. The optimal concentration of Sr2+ ion is 40%, and the phosphor shows high color stability in CIE chromaticity diagram. The result indicates that Sr2+ doped phosphor not only can enhance the relative intensity but also can adjust the chromaticity coordinate. 相似文献
9.
Divalent europium-activated chlorosilicate Ca6Sr4(Si2O7)3Cl2:Eu2+ phosphors were synthesized by a conventional solid-state reaction under reductive atmosphere. These phosphors can be efficiently excited by UV–visible light from 320 to 420 nm, which matches that of a near UV-emitting InGaN chip. Under the 360 nm excitation, Ca6Sr3.97(Si2O7)3Cl2:0.03Eu2+ phosphor shows a strong and broad emission centering at 515 nm, which is attributed to the 5d→4f transition of Eu2+ ion. The mechanism of concentration quenching was determined to be the dipole–dipole interaction and the critical energy-transfer distance of Eu2+ was calculated as 3.31 nm. The CIE chromaticity coordinates of Ca6Sr3.96(Si2O7)3Cl2:0.03Eu2+ phosphor are (0.127, 0.770) according to the emission spectrum. It can be expected that Ca6Sr4(Si2O7)3Cl2:Eu2+ phosphor is a promising candidate as the green component for near-ultraviolet InGaN-based white LED. 相似文献
10.
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
11.
Y2O3 luminescent nanoparticles were synthesized via PVA-assisted sol-gel method and their structural and optical properties were investigated. Effects of rare earth (Er3+, Eu3+ and Tb3+) doping on luminescence properties of the produced nanophosphors have been investigated under NIR (800 nm) and UV (240–300 nm) excitation. Intense infrared to red and green emissions were observed and a weak blue upconverted luminescence was also detected. Moreover, it was observed that changing the doping ions, the color emitted by the samples could be modified and different combinations of UV excitation and doping produced effective white light emissions. The obtained results demonstrate that PVA-assisted sol-gel is an effective methodology for the synthesis of rare-earth doped Y2O3 nanophosphors. 相似文献
12.
Fengjiao Qian Renli Fu Simeon Agathopoulos Xiguang Gu Xiufeng Song 《Journal of luminescence》2012,132(1):71-75
Single-phase broad-band red-emitting Ca3Si2O7:Eu2+ phosphors, with photoluminescence features that qualify them as candidates for white light-emitting diodes applications, were successfully synthesized via a modified solid-state reaction method that employed H3BO3 as a flux. The phosphors produced have an intense broad red emission band, with a peak at 603 nm, a full width at half maximum of 110 nm, and color coordinates of (0.550, 0.438). Concentration quenching occurred at 0.01 mol Eu2+. The discussion of the results shows that Eu2+ ions should be accommodated at the Ca-sites of the lattice, dipole–dipole interactions should predominantly govern the energy transfer mechanism among them, and the critical distance between them is ~31 Å. 相似文献
13.
The photoluminescence properties in UV and N-UV excitable range for the phosphors of Na2La2B2O7: RE (RE=Eu, Tb, Ce, Sm, Gd) are investigated. The solution combustion synthesis technique was employed for the synthesis of the phosphors Na2La2B2O7: RE. The photoluminescence measurements of the phosphors were carried out on a HITACHI F7000 Fluorescence Spectrophotometer. The PL and PL excitation (PLE) spectra indicate that the main emission wavelength of Na2La2B2O7: Eu are 591 and 615 nm, Na2La2B2O7: Ce shows dominating emission peak at 387 nm and Na2La2B2O7: Tb displays green emission at 493, 544, 593 and 620 nm at 254 nm excitation, while Na2La2B2O7: Sm shows the main emission peak wavelengths 566 and 604 nm at 405 nm excitation and Na2La2B2O7: Gd shows dominating emission peak at 312 nm at 274 nm excitation. These phosphors may provide a new kind of luminescent materials under ultraviolet and near ultraviolet excitation for various applications. 相似文献
14.
Ru-Yuan Yang Min Hang Weng Huang-Yu Chen Chin-Min Hsiung Shin-Hung Chen 《Journal of luminescence》2012,132(2):478-483
This paper describes an investigation of the crystalline morphology and photoluminescent properties of YInGe2O7 powders doped with different Eu3+ concentrations using microwave assisted sintering and conventional sintering. X-ray powder diffraction analysis confirmed the formation of monoclinic YInGe2O7 structure as YInGe2O7:Eu3+ powders were sintered at 1200 °C in microwave furnace for 1 h, and the raw material phase of Y2O3 was observed when Eu3+ concentration was below 30 mol%. Scanning electron microscopy showed microwave assisted sintering results in smaller particle size and more uniform grain size distribution. In the photoluminescent (PL) studies, the concentration quenching effect was observed under the excitation at 393 nm, but not under the excitation at CTS band. The 5D0→7F2 transition (620 nm), exhibits a non-exponential decay behavior as YInGe2O7:Eu3+ powders were sintered by microwave with the Eu3+ concentration higher than 50 mol%. 相似文献
15.
Mithlesh Kumar T.K. Seshagiri M. Mohapatra V. Natarajan S.V. Godbole 《Journal of luminescence》2012,132(10):2810-2816
Eu3+-doped ZnAl2O4 phosphors were successfully synthesized in air atmosphere at 900 °C. The phosphors were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermally stimulated luminescence (TSL) and photoluminescence (PL) techniques. The average particle size of the system as determined from SEM was found to be 100–150 nm (for samples annealed at 900 °C). PL spectra of the doped phosphors showed emission peaks corresponding to Eu3+ ions. Lifetime studies revealed Eu3+ ions to be in two different sites. The asymmetric ratio (I616/I592) was observed to be about 3.75. This suggested that Eu3+ ion entered the host mainly substituting Al3+ site distorting the local environment and is partly located on surface of the phosphors. A prominent glow peak at 430 K was observed in the TSL of γ-irradiated Eu3+-doped ZnAl2O4 phosphors. Trap parameters for this peak have been determined and the probable mechanism for the glow peak is proposed. CIE chromaticity coordinates for the system were evaluated. It was observed that, the system could be employed as a potential red emitting phosphor. Commercial utility of the phosphor was investigated by comparing it with commercial red phosphor. The PL intensity of the as prepared phosphors was 63% of that of the commercial phosphor. Apart from this, various radiative properties such as the Judd–Ofelt intensity parameters, spontaneous emission probabilities, luminescence branching ratios, radiative lifetimes and quantum efficiency were evaluated for the system. 相似文献
16.
Here we reported photoluminescence properties of Eu2+ activated in novel and existing MgXAl10O17 (X = Sr, Ca) phosphor which has been prepared by combustion synthesis at 550 °C under UV and near UV excitation wavelength. The PL emission properties of MgSrAl10O17:Eu2+ were monitored at 254 nm and 354 nm respectively keeping emission wavelength at 469 nm. Whereas novel MgCaAl10O17:Eu2+ exhibit emission band at 452 nm keeping excitation at 378 nm. These blue emission corresponds to 4f65d1 → 4f7 transition of Eu2+ ions. Further phosphor was analyzed by XRD for the confirmation of desired phase and purity. 相似文献
17.
We report on the preparation of Eu2+-doped BaSi2O5 glass-ceramics by crystallizing an Eu3+-doped barium-silicate glass at temperatures in the range from 750 to 1100 °C. Single phase BaSi2O5 glass ceramics can be obtained by thermal annealing at temperatures of about 950 °C. The luminescence intensity of Eu2+ increases dramatically if monoclinic BaSi2O5 is formed. Monoclinic Eu2+:BaSi2O5 shows efficient, broad band luminescence between 450 and 550 nm by excitation in the near UV. Annealing at temperatures >1000 °C leads to orthorhombic BaSi2O5 with much smaller Eu2+ luminescence. Static and time-resolved luminescence measurements indicate that Eu2+ ions are incorporated into the BaSi2O5 crystallites while Eu3+ ions remain in the amorphous phase. 相似文献
18.
Yu-qiang Zhang Xue-jian Liu Zheng-ren Huang Jian Chen Yan Yang 《Journal of luminescence》2012,132(10):2561-2565
Eu2+–Mn2+ codoped Ca-α-SiAlON phosphors, Ca0.736?ySi9.6Al2.4O0.8N15.2:0.064 Eu2+, yMn2+, were firstly synthesized by the high temperature solid state reaction method. The effects of doped Eu2+ and Eu2+–Mn2+ concentrations on the photoluminescence properties of the as-prepared phosphors were investigated systematically. Powder X-ray diffraction shows that pure Ca-α-SiAlON phase is synthesized after sintering at 1700 °C for 2 h under 0.5 MPa N2 atmosphere. The excitation spectra of Eu2+-doped Ca-α-SiAlON phosphors are characterized by two dominant bands centered at 286 nm and 395 nm, respectively. The photoluminescent spectrum of Eu2+-doped Ca-α-SiAlON phosphor exhibits an intense emission band centered at 580 nm due to the allowed 4f 65d→4f 7 transition of Eu2+, showing that the phosphor is a good candidate for creating white light when coupled to a blue LED chip. The intensities of both excitation and emission spectra monotonously decrease with the increment of codoped Mn2+ content (i.e. y value), indicating that energy transfer between Eu2+ and Mn2+ is inefficient in the case of Eu2+–Mn2+ codoped Ca-α-SiAlON phosphors. 相似文献
19.
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 5D0→7F2 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
20.
In this paper we report the combustion synthesis of rare earth (RE=Eu, Dy) doped Ba4Al2O7 phosphors. Prepared phosphors were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), CIE color co-ordinates and their photoluminescence (PL) properties were also investigated. In case of Ba4Al2O7: Eu2+, the emission spectra show unique band centered at 495 nm, which corresponds to the 4f65d1→4f7 transition of Eu2+, and PL emission spectra of Dy3+ ion under 348 nm excitation give two bands centered at 478 nm (blue) and 575 nm (yellow), which originate from the transitions of 4F9/2→6H15/2 and 4F9/2→6H13/2 of Dy3+, respectively. The results indicate that the Eu2+ and Dy3+ activated Ba4Al2O7 phosphor could find application in solid state lighting. 相似文献