共查询到20条相似文献,搜索用时 15 毫秒
1.
Zhenhe Xu 《Materials Research Bulletin》2009,44(9):1850-1857
One-dimensional (1D) Y2O3:Tb3+ and Gd2O3:Tb3+ microrods have been successfully prepared through a large-scale and facile hydrothermal method followed by a subsequent calcination process in N2/H2 mixed atmosphere. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (IR), thermogravimetric analysis (TGA), energy-dispersive X-ray spectra (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), photoluminescence (PL) and cathodoluminescence (CL) spectra as well as kinetic decays were used to characterize the samples. The as-formed products via the hydrothermal process could transform to cubic Y2O3:Tb3+ and Gd2O3:Tb3+ with the same morphology and slight shrinking in size after a postannealing process. Both Y2O3:Tb3+ and Gd2O3:Tb3+ microrods exhibit strong green emission corresponding to 5D4 → 7F5 transition (542 nm) of Tb3+ under UV light excitation (307 and 258 nm, respectively), and low-voltage electron beam excitation (1.5 → 3.5 kV), which have potential applications in fluorescent lamps and field emission displays. 相似文献
2.
The luminescent properties of Na3Y1−xSi3O9:xEu3+ (0.05 ≦ x ≦ 0.80) powder crystals were investigated in UV-VUV region. The Eu3+-O2− charge transfer band (CTB) was observed to be located at around 233 nm and the environmental parameter (he) was estimated to be about 0.730. The excitation spectrum monitoring the 613 nm red emission from Eu3+ ions reveals the host absorption band (HAB) to be around 145 nm. The calculated Commission Internationale de l’Eclairage (CIE) chromaticity coordinates indicate the emission by 233 nm rather than by 147 nm excitation has the better color purity and the possible mechanisms have been proposed. The Eu3+-emission showed high quenching concentration due to the isolated YO6 octahedra in the host and the small he for the Eu3+ ions and the optimum concentration was determined to be as high as x = 0.65 and 0.30 with 233 and 147 nm excitation, respectively. 相似文献
3.
CaTiO3:Pr3+ phosphors codoped with Bi3+ ions were synthesized by a peroxide-based route (PBR). The effect of codopants on the structural and luminescence properties was studied. Boric acid used as flux material was proved to be effective in improving the luminescence property. The phosphors prepared by the PBR method showed advantages of lower sintering temperature, shorter heating time, and small grain size. The CaTiO3:Pr3+,Bi3+ demonstrated to be a potential red-emitting phosphor for white light-emitting diodes. 相似文献
4.
Lili Wang Zhiyao Hou Zewei Quan Hongzhou Lian Piaoping Yang Jun Lin 《Materials Research Bulletin》2009,44(10):1978-1983
One-dimensional Mn2+-doped ZnGa2O4 nanofibers were prepared by a simple and cost-effective electrospinning process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), energy-dispersive X-ray spectrum (EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL) and cathodoluminescence (CL) spectra as well as kinetic decays were used to characterize the samples. SEM results indicated that the as-formed precursor fibers and those annealed at 700 °C are uniform with length of several tens to hundred micrometers, and the diameters of the fibers decrease greatly after being heated at 700 °C. Under ultraviolet excitation (246 nm) and low-voltage electron beams (1–3 kV) excitation, the ZnGa2O4:Mn2+ nanofibers presents the blue emission band of the ZnGa2O4 host lattice and the strong green emission with a peak at 505 nm corresponding to the 4T1–6A1 transition of Mn2+ ion. 相似文献
5.
Volker Kahlenberg 《Materials Research Bulletin》2002,37(4):715-726
Sr10Al6O19 is monoclinic, space group C12/c1, a=34.5823(21) Å, b=7.8460(6) Å, c=15.7485(9) Å, β=103.68(1)°, V=4151.9(7) Å3, Z=8. The structure has been solved from a single crystal diffraction dataset by direct methods and subsequently refined by a full-matrix least-squares process to a residual index of R(|F|)=0.038 for 2537 observed reflections with I>2σ(I). The compound is an oligoaluminate containing highly puckered [Al6O19]-groups of corner-sharing tetrahedra; it is the first purely aluminate cluster of this type, but it resembles the [□6O19]-group recently found in α-Sr10□6O19. Linkage between the hexamers is provided by 11 crystallographically different strontium atoms located in planes parallel (1 0 0). They are coordinated by six-eight next oxygen neighbours. The structure can be derived from perovskite, ABO3, by introducing ordered vacancies into the substructure of the oxygen atoms. The A-sites in Sr10Al6O19 are exclusively occupied by Sr atoms, whereas strontium and aluminum atoms reside on the B-positions in the ratio 1:3. The relationship with perovskite can be expressed in the crystal chemical formula Sr(Al3/4Sr1/4)(O19/8□5/8). 相似文献
6.
Undoped and doped either by Eu3+ or Tb3+ bismuth borate Ba3BiB9O18 was structurally characterized and analyzed by fluorescence spectroscopy. Belonging to synthetic borate member of the family Ba3XB9O18, layers of planar triangular B3O6 groups connecting with deformed BaO6 hexagons are interleaved by 9-coordinate Ba atoms, and 6-coordinate Bi atoms. Its crystal structure was determined and refined from powder X-ray diffraction data by the Rietveld method and the results showed that Ba3BiB9O18 belongs to space group P63/m with unit cell dimensions of a = 7.1999(2) Å, c = 17.3567(6) Å, and z = 2. Curves of differential thermal analysis and thermogravimetric analysis showed that Ba3BiB9O18 is a congruent melting compound and chemically stable above 728 °C. Ba3Bi1−xEuxB9O18 and Ba3Bi1−xTbxB9O18 form a continuous solid solution from x = 0.01 to x = 0.9. The ultraviolet excited photoluminescence intensity increased with both Eu3+ and Tb3+ concentration in the matrix of Ba3BiB9O18. There may be an interesting correlation between spectroscopic properties and lattice structural features of doped Ba3BiB9O18. 相似文献
7.
Y2O3:Eu3+ red phosphors were prepared by surfactant assisted co-precipitation-molten salt synthesis method. The effects of surfactant content and annealing temperature on the structure and luminescence were investigated by X-ray diffraction and fluorescence spectrophotometer. The use of surfactant reduces the impurities on the surface of particles and promotes the reaction. The color purity of as-prepared Y2O3:Eu3+ red phosphors is improved with the presence of surfactant. In the excitation spectra, two strong bands at 394 and 466 nm are attributed to 7F0,1-5L6, 7F0,1-5D2 transitions of Eu3+ ions respectively. With the excitation of 394 or 466 nm, the as-fabricated samples reveal excellent red emission as high as that of samples monitored by 254 nm. Thus, the Y2O3:Eu3+ is a promising red phosphor for ultraviolet-visible light-emitting diodes. 相似文献
8.
Chuan HeYongfeng Guan Lianzeng YaoWeili Cai Xiaoguang LiZhen Yao 《Materials Research Bulletin》2003,38(6):973-979
We report nano-Y2O3:Eu3+ phosphors with particle size of about 50 nm and relatively high photoluminescence (PL) intensity which is close to the standard for application. The influences of the dope amount, the surfactant and the precipitation pH on the PL intensity, the particle size and the dispersion have been studied. It has been found that 4% is the best Eu3+ molar concentration to get the highest PL intensity for both nano- and micro-Y2O3:Eu3+. The addition of butanol as a surfactant inhibits the grain growth and the agglomeration of particles efficiently by reducing the oxygen bridge bonds. As the pH rises, the PL intensity and the particle size increase due to the formation of oxygen bridge bonds. 相似文献
9.
Nathalie Pradal Audrey Potdevin Geneviève Chadeyron Rachid Mahiou 《Materials Research Bulletin》2011,46(4):563-568
Blue-emitting Eu2+-doped barium magnesium aluminate (BaMgAl10O17:Eu2+) for advanced displays and lighting devices was prepared by a microwave induced solution combustion synthesis using urea as combustion fuel and nitrates as oxidizer. Purity control of as-synthesized blue phosphor particles was undertaken by modifying the fuel to oxidizer molar ratio. X-ray diffraction, scanning electron microscopy and photoluminescence were used to investigate powders crystallinity, particles size, morphology and luminescent properties, respectively. Fuel-rich urea reactions preferentially lead to pure phases compared to the powders synthesized with a stoichiometric fuel to oxidizer ratio. In both cases, we produce a nearly pure well-crystallized and nanostructured BaMgAl10O17:Eu2+. Photoluminescence measurements exhibit the characteristic blue emission of Eu2+ under UV light excitation however a weak red emission associated to Eu3+ is also detected. 相似文献
10.
Rare-earth ions (Eu3+, Tb3+, Dy3+) doped SrMoO4 nanoparticles were prepared by solvothermal route using oleic acid as surfactant to control the particle shape and size. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), photoluminescence spectra (PL) and the kinetic decay times were applied to characterize the obtained samples. The XRD patterns reveal that all the doped samples are assigned to the scheelite-type tetragonal structure of SrMoO4 phase. In addition, the as-synthesized SrMoO4:Ln (Ln = Eu3+, Tb3+, Dy3+) particles are high purity well crystallized and with the average size of 30-50 nm. The possible formation process of SrMoO4:Ln (Ln = Eu3+, Tb3+, Dy3+) nanoparticles have been discussed as well. Upon excitation by ultraviolet radiation, the as-synthesized SrMoO4:Ln (Ln = Eu3+, Tb3+, Dy3+) nanoparticles exhibit the characteristic emission lines of corresponding Eu3+, Tb3+, Dy3+, respectively. 相似文献
11.
Shinobu Hashimoto Kentaro Hattori Ayuka Nakahashi Yuji Iwamoto 《Materials Research Bulletin》2009,44(1):70-3888
Pure-phase LiAl5O8 was selected as an oxide ceramic red phosphor material without dopants (color centers) and was synthesized using a self-flux method. The LiAl5O8 was formed by heating a powder mixture consisting of γ-Al2O3:Li2SO4 = 1:2 (molar ratio) at over 1100 °C for 1 h. Photoluminescence (PL) properties for the synthesized LiAl5O8 were investigated. The maximum intensity of the excitation spectrum for the photoluminescent emission of LiAl5O8 synthesized was at 274 nm. The peak intensity of the emission spectrum was at a wavelength of 667 nm (red color). The intensity of the peak emission spectrum increased with the heating temperature, i.e., the maximum peak intensity of the red emission spectrum was detected for the LiAl5O8 synthesized by heating at 1500 °C for 1 h. 相似文献
12.
Ping YangMeng Kai Lü Chun Feng SongDong Xu Duo Rong YuanGuang Ming Xia Yong Xin QiSu Wen Liu Jian Xing Shen 《Materials Research Bulletin》2003,38(5):757-763
The luminescence of sol-gel derived Zn2SiO4 powder sample doped with Bi3+ ions has been presented in this paper. From the photoluminescence (PL) spectra of the doped sample, it can be concluded that Bi3+-doped Zn2SiO4 powder is an interesting PL material whose luminescence properties are adjusted by changing the excitation wavelength. The luminescence of Bi3+ ions is quite diverse in Zn2SiO4 powder sample. The blue and yellow emission bands have been observed from the doped Zn2SiO4 powder. This novel luminescence property is attributed to an energy transfer involving Bi3+, Zn2+, and Si4+ ligand of Zn2SiO4 lattice. 相似文献
13.
Eu3+- and Tb3+-activated SrGdGa3O7 phosphors were synthesized by the solid-state reaction and their luminescence properties were investigated. Sr(Gd1 − xEux)Ga3O7 and Sr(Gd1 − xTbx)Ga3O7 formed continuous solid solution in the range of x = 0-1.0. Unactivated SrGdGa3O7 exhibited a typical characteristic excitation and emission of Gd ion. The SrGdGa3O7:xEu3+ and SrGdGa3O7:xTb3+ phosphors also showed the well-known Eu3+ and Tb3+ excitation and emission. The energy transfer from Gd3+ to Eu3+ and Tb3+ were verified by photoluminescence spectra. The dependence of photoluminescence intensity on Eu3+ and Tb3+ concentration were also studied in detail and the photoluminescence (PL) intensity of SrGdGa3O7:Eu and SrGdGa3O7:Tb were compared with commercial phosphors, Y2O3:Eu and LaPO4:Ce,Tb. The luminescence decay measurements showed that the lifetimes of Eu3+ and Tb3+ were in the range of microsecond. The energy transfer from Gd3+ to Tb3+ was also observed in decay curve. 相似文献
14.
The phosphors in the system Sr2−x−yP2O7:xEu2+,yMn2+ were synthesized by solid-state reactions and their photoluminescence properties were investigated. These phosphors have strong absorption in the near UV region, which is suitable for excitation of ultraviolet light emitting diodes (UVLEDs). The orange-reddish emission of Mn2+ in these phosphors can be used as a red component in the tri-color system and may be enhanced by adjusting the Mn2+/Eu2+ ratio. The energy transfer from Eu2+ to Mn2+ is observed with a transfer efficiency of ∼0.45 and a critical distance of ∼10 Å. The results reveal that Sr2−x−yP2O7:xEu2+,yMn2+ phosphors could be used in white light UVLEDs. 相似文献
15.
A novel broadband emission phosphor Ca2KMg2V3O12 was first synthesized by solution combustion method. The X-ray diffraction showed that Ca2KMg2V3O12 phase can be obtained at 600-900 °C through combustion route. The crystal structure of this material was refined by Rietveld method using powder X-ray diffraction. It crystallizes in cubic system and belongs to space group Ia3d with z = 8, a = 0.12500 nm. The excitation band of Ca2KMg2V3O12 peaks at 320 nm in a region between 260 nm and 425 nm, and the emission spectrum exhibits an intense band centered at about 528 nm covering from 400 nm to 800 nm. The colour coordinates of samples prepared at different ignition temperatures are in a range of x = 0.323-0.339, y = 0.430-0.447. 相似文献
16.
Jinsheng Liao Bao Qiu Herui Wen Jinglin Chen Weixiong You 《Materials Research Bulletin》2009,44(9):1863-868
Tb3+-doped SrWO4 phosphors with a scheelite structure have been prepared by hydrothermal reaction. X-ray powder diffraction, field-emission scanning electron microscopy, photoluminescence excitation and emission spectra and decay curve were used to characterize the resulting samples. Scanning electron microscopy image showed that the obtained SrWO4:Tb3+ phosphors appeared to be nearly spherical and their sizes ranged from 1 to 3 μm. Photoluminescence spectra indicated the phosphors emitted strong green light centered at 545 nm under ultraviolet light excitation. Because 12 at.% SWO4:Tb3+ phosphor exhibits intensive green emission under 254 nm excitation in comparison with the commercial green fluorescent lamp phosphor (LaPO4:Ce,Tb), the excellent luminescence properties make it a new promising green phosphor for fluorescent lamps application. 相似文献
17.
Haoyi Wu Fengwen Kang Li Chen Xiaojuan Wang Guifang Ju Zhongfei Mu 《Materials Research Bulletin》2011,46(12):2489-2493
The Tb3+ doped CaWO4 phosphors are synthesized via high temperature solid state reaction. The X-ray diffraction shows that small amount of Tb3+ does not have a significant influence on the structure of CaWO4. A broad absorption band of the WO42− group is observed from photoluminescence and the energy transfer from WO42− group to Tb3+ ions induces the f-f transition. The cross-relaxation between two adjacent Tb3+ ions weakens 5D3-7Fj transitions and enhances the 5D4-7Fj transitions, leading to a green long afterglow of the phosphors. The thermoluminescence curves centered around 75 °C reveal the trap depth for afterglow generation is about 0.74-0.77 eV. The optimum Tb3+ concentration for afterglow properties is about 1%. A deep hole trap is induced when Tb3+ concentration exceeds 1% and it suppresses the thermoluminescence and the decay properties. 相似文献
18.
(Gd1−x,Eux)2O2SO4 nano-phosphors were synthesized by a novel co-precipitation method from commercially available Gd2O3, Eu2O3, H2SO4 and NaOH starting materials. Composition of the precursor is greatly influenced by the molar ratio of NaOH to (Gd1−x,Eux)2(SO4)3 (the m value), and the optimal m value was found to be 4. Fourier transform infrared spectrum (FT-IR) and thermal analysis show that the precursor (m = 4) can be transformed into pure (Gd1−x,Eux)2O2SO4 nano-phosphor by calcining at 900 °C for 2 h in air. Transmission electron microscope (TEM) observation shows that the Gd2O2SO4 phosphor particles (m = 4) are quasi-spherical in shape and well dispersed, with a mean particle size of about 30-50 nm. Photoluminescence (PL) spectroscopy reveals that the strongest emission peak is located at 617 nm under 271 nm light excitation, which corresponds to the 5D0 → 7F2 transition of Eu3+ ions. The quenching concentration of Eu3+ ions is 10 mol% and the concentration quenching mechanism is exchange interaction among the Eu3+ ions. Decay study reveals that the 5D0 → 7F2 transition of Eu3+ ions has a single exponential decay behavior. 相似文献
19.
Undoped and Eu-doped yttrium aluminum garnet nano-powders were prepared by a facile combustion method with citric acid/ethylene diamine tetraacetic acid (EDTA) as fuels and nitrates as oxidizers. The precursors and powders calcined at 1030 °C were investigated using thermogravimetric (TG), differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscope (SEM), and Brunauer-Emmett-Teller (BET) surface area measurements. It was found that the powders could be indexed with a garnet structure. The grains were in shape of hemispherical with sizes between 60 nm and 100 nm. With decreasing the citric acid/EDTA ratio, the crystallite size decreased steadily and the specific surface area increased. Investigations of photoluminescence (PL) revealed that as-synthesized YAG:Eu3+ phosphor samples exhibited an orange emission band with a main peak at 591 nm under the excitation of 394 nm. As citric acid amounts increased, the quality of crystallinity became higher and the luminescent properties were monotonously enhanced. 相似文献
20.