共查询到20条相似文献,搜索用时 15 毫秒
1.
Huiming Ji Guijiu Xie Ying Lv Huixiang Lu 《Journal of Sol-Gel Science and Technology》2007,44(2):133-137
The flower-like phosphors of Sr2MgSi2O7: Eu2+, Dy3+ with high brightness and long afterglow were obtained by sol–gel method. X-ray diffraction pattern (XRD) shows that single-phased
Sr2MgSi2O7 phosphor is prepared by sol–gel method under 1250 °C. Scanning electron microscope (SEM) indicates that the phosphor consists
of nano-sized whiskers which are detected for the first time in Eu2+ and Dy3+ co-doped long-lasting phosphorescence silicates. Furthermore, the investigation on the mechanism indicates that the internal
structure and gas, liquid and solid phase effect play important roles in the formation of flower-like Sr2MgSi2O7: Eu2+, Dy3+ nanostructure. Finally, the optical properties of flower-like Sr2MgSi2O7 nanostructure have been characterized by photoluminescence (PL) spectra. 相似文献
2.
Eu, Dy co-doped strontium aluminate nanophosphors were prepared by the combustion synthesis method. Their structure and morphology were investigated by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy. According to the XRD and the TEM analysis, the average crystallite size was found to be in the nanometer range. The phase structure of the prepared nanophosphor is consistent with a standard monoclinic phase with a space group P21. The prepared SrAl2O4:Eu2+, Dy3+ nanophosphor emitted green light with a peak at 510 nm showing blue shift, which is due to the reduction in the particle size. Two distinct peaks were observed in the ML intensity versus time curve. The two peaks in ML indicate the presence of charge transfer in an ML process. 相似文献
3.
Ishwar Prasad Sahu D. P. Bisen Raunak Kumar Tamrakar Ravi Shrivastava 《Research on Chemical Intermediates》2016,42(3):1823-1843
The Ca2MgSi2O7:Eu2+ and Ca2MgSi2O7:Eu2+, Dy3+ long afterglow phosphors were synthesized under a weak reducing atmosphere by the traditional high temperature solid state reaction method. The synthesized phosphors were characterized by powder X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) techniques. The luminescence properties were investigated using thermoluminescence (TL), photoluminescence (PL), long afterglow, mechanoluminescence (ML), and ML spectra techniques. The crystal structure of sintered phosphors was an akermanite type structure, which belongs to the tetragonal crystallography. TL properties of these phosphors were investigated, and the results were also compared. Under the ultraviolet excitation, the emission spectra of both prepared phosphors were composed of a broad band peaking at 535 nm, belonging to the broad emission band. When the Ca2MgSi2O7:Eu2+ phosphor is co-doped with Dy3+, the PL, afterglow and ML intensity is strongly enhanced. The decay graph indicates that both the sintered phosphors contain fast decay and slow decay process. The ML intensities of Ca2MgSi2O7:Eu2+ and Ca2MgSi2O7:Eu2+, Dy3+ phosphors were proportionally increased with the increase of impact velocity, which suggests that this phosphor can be used as sensors to detect the stress of an object. 相似文献
4.
CaAl2O4:Eu2+, Nd3+@TiO2 composite powders were synthesized by a sol–gel method under mild conditions (i.e. low temperature and ambient pressure).
The as-prepared powders were characterized by transmission electron microscopy (TEM) and analyzed by X-ray diffraction (XRD).
The photocatalytic behavior of the TiO2-base surfaces was evaluated by the degradation of nitrogen monoxide gas. It suggested that CaAl2O4:Eu2+, Nd3+@TiO2 composite powders were composed of anatase titania and that CaAl2O4:Eu2+, Nd3+. TiO2 particles were deposited on the surface of CaAl2O4:Eu2+, Nd3+ to form uniform film. CaAl2O4:Eu2+, Nd3+@TiO2 composite powders exhibited higher photocatalytic activity compared with pure TiO2 under visible light. And the result also clearly indicated that the long afterglow phosphor absorbed and stored lights for
the TiO2 to remain photocatalytic activity in the dark. 相似文献
5.
Qinan Mao Qianmin Yuan Zhenguo Ji Junhua Xi Zhe Kong Jun Zhang 《Research on Chemical Intermediates》2016,42(8):6557-6566
Eu2+/Dy3+-codoped BaAl2O4 phosphors were prepared by conventional solid-state reaction with boric acid flux. The effects of boric acid on structural and luminescent properties of BaAl2O4:(Eu2+, Dy3+) were investigated. The crystallinity of BaAl2O4 improved with increasing amount of H3BO3. Incorporation of Eu2+ and Dy3+ ions into effective lattice sites was promoted by H3BO3 addition. As a result, Eu2+ emission in BaAl2O4 was greatly enhanced by H3BO3, and the duration of persistent luminescence increased with the amount of H3BO3. However, the decay lifetime of persistent luminescence was not strongly influenced by the amount of H3BO3. 相似文献
6.
7.
Eu3+ ion-doped LaPO4 nanowires or nanorods have been successfully synthesized by a simple hydrothermal method. The influence of varying the hydrothermal
and subsequent sintering conditions on the morphology and structure of the LaPO4 host has been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). For comparison, the Eu3+ ions were also doped into monoclinic monazite LaPO4 nanoparticles and perovskite LaAlO3 nanoparticles. The relative intensities of the emission lines of the LaPO4:Eu3+ nanosystems were essentially independent of their shape. The optimal doping concentrations in the monoclinic LaPO4 and perovskite LaAlO3 nanosystems were determined to be about 5.0 and 3.5 mol%, respectively. Under appropriate UV-radiation, the red light emitted
from LaAlO3:Eu3+ (3.5 mol%) was brighter than that from LaPO4:Eu3+ (5.0 mol%) nanomaterial, resulting from differences in their spin-orbit couplings and covalence, which indicates that the
nanoscale LaAlO3 is a promising host material for rare earth ions.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.
Supported by the National Natural Science Foundation of China (Grant Nos. 20873039 & 90606001), Hunan Provincial Natural Science
Foundation (No. 07jj4002), and the Students Innovation Training Fund of Hunan University 相似文献
8.
O. V. Davydova N. E. Drobyshevskaya E. N. Poddenezhnyi A. A. Boiko A. V. Zdravkov N. N. Khimich 《Russian Journal of Applied Chemistry》2016,89(10):1601-1606
Powders were synthesized in the yttrium oxide + zinc oxide system doped with europium oxide by the method of redox combustion of a mixture of yttrium, zinc, and europium nitrates in the presence of saccharose (fuel). The structure and the physicochemical and luminescent properties of the particles being formed and of a ceramic on their basis were examined. 相似文献
9.
Virginie Gueu Hongpeng You Tomokatsu Hayakawa Masayuki Nogami 《Journal of Sol-Gel Science and Technology》2007,41(3):231-236
Fluorescence and spectral hole burning properties of Eu3+ ions were studied in nanocrystals-precipitated SnO2-SiO2 glasses. The glasses were prepared to contain various amount of Eu2O3 using the sol-gel method, in which SnO2 nanocrystals were precipitated by heating in air. In the glasses containing Eu2O3 less than 1%, the Eu3+ ions were preferentially doped in the SnO2 nanocrystals and their fluorescence intensities were enhanced by the energy transfer due to the recombination of electrons
and holes excited in SnO2 crystals. The SnO2 nanocrystals-precipitated glasses exhibited the persistent spectral holes with the depth of ∼25% of the total fluorescence
intensities of the Eu3+ ions. With the increasing Eu2O3 concentration, the amount of SnO2 nanocrystals decreased and the Sn4+ ions formed the random glass structure together with the silica network. This structure change induced the fluorescence intensities
and the hole depth to decrease. 相似文献
10.
Y. Akishige H. Shigematsu T. Tojo H. Kawaji T. Atake 《Journal of Thermal Analysis and Calorimetry》2005,81(3):537-540
Summary Specific heats on the single crystals of Sr2Nb2O7, Sr2Ta2O7 and (Sr1-xBax)2Nb2O7 were measured in a wide temperature range of 2-600 K. Heat anomalies of a λ-type were observed at the incommensurate phase transition of TINC (=495 K) on Sr2Nb2O7 and at the super-lattice phase transition of TSL (=443 K) on Sr2Ta2O7; the transition enthalpies and the transition entropies were estimated. Furthermore, a small heat anomaly was observed at the low temperature ferroelectric phase transition of TLOW (=95 K) on Sr2Nb2O7. The transition temperature TLOW decreases with increasing Ba content x and it vanishes for samples of x>2%. 相似文献
11.
Sungho Cho Hyungwon Lee Chiwoong Moon Jaehyung Kim Jikoon Park Gyerok Jeon Rena Lee Sanghee Nam 《Journal of Sol-Gel Science and Technology》2010,53(2):171-175
Fine Eu3+-doped lutetium oxide (Lu2O3:Eu3+) nanophosphor were synthesized using a low-temperature solution-combustion method in a methyl-alcohol solution. The characteristics
of the nanophosphors synthesized at various sintering temperatures with different Eu3+ concentrations were analyzed to determine the optimum synthesis conditions. Thermogravimetry/differential thermal analysis
showed that Lu2O3:Eu3+ crystallizes completely when the dry powder is sintered at 500 °C. The Lu2O3:Eu3+ crystals had a cubic structure and monoclinic phase. The peak position of the luminescence spectrum did not differ with the
concentration of Eu or the sintering temperature or atmosphere, whereas the luminescence intensity was strongly dependent
on the concentration and sintering conditions. 相似文献
12.
13.
We have investigated the presence of foreign ions into the bulk structure and the external surfaces of aragonite using periodic
ab-initio methods. Four cations isovalent to Ca2+ were studied: Mg2+, Sr2+, Ba2+ and Zn2+. The calculations were performed at structures (bulk, surface) that contain four and eight CaCO3 units. Our results, at the Hartree-Fock level, show that the incorporation of those ions into aragonite depends strongly
on their size. Mg2+ and Zn2+, due to their smaller size, can substitute Ca2+ ions in the crystal lattice while the incorporation of Sr2+ and Ba2+ into aragonite is energetically less favoured. Examination of the [011], [110] and [001] surfaces of aragonite revealed that
the surface incorporation reduces the energetic cost for the larger ions. These systems provide challenging examples for most
shape analysis methods applied in Mathematical Chemistry. 相似文献
14.
Abhijit P. Jadhav Sovann Khan Sun Jin Kim Seung Yong Lee Jong-Ku Park So-Hye Cho 《Research on Chemical Intermediates》2017,43(6):3463-3471
Properties of the quantum-cutting phosphors are dependent on various factors such as dopant concentration, crystallinity, homogeneity, particle size and surface morphology. Effective control of the above parameters can enhance the quantum-cutting ability of the phosphor material. Nano-sized particles of Y2O3:Tb3+,Yb3+ were prepared with a solution-based co-precipitation method and subsequent calcination. Effective control of the reaction parameters and doping concentration helped to produce uniform nanostructures with high quantum-cutting efficiency up to 181.1 %. The energy transfer mechanism between Tb3+ and Yb3+ was studied by considering their spectroscopic properties and time-resolved spectroscopy. The high efficiency and small particle size of the quantum-cutting phosphor Y2O3:Tb3+,Yb3+ make it a suitable candidate for its application in solar cells. 相似文献
15.
E. S. Zakaria 《Journal of Radioanalytical and Nuclear Chemistry》2005,264(3):629-635
Summary This paper reports the radiochemical study of the ion-exchange of Cs+, Na+, Sr2+ and Eu3+ ions with H+ by chromium hexacyanoferrate(II) which was prepared in a granular form using a gel method. The slow steps which determine the rate of exchange of these ions are directly proportional to the particle diameter and this is confirmed from the linearity test of Bt vs. t plots at different particle diameters. Boyed’s equation and Reichenberg’s tables were used for evaluating all the kinetic parameters. The results reveal that the effective particle radii are unchanged for both chromium hexacyanoferrate(II) dried at 60 and 120 °C. The obtained data were analyzed using McKay plots and Arrhenius equation and the kinetic and thermodynamic parameters, e.g., effective diffusion coefficient, activation energies and entropies of activation have been evaluated. The mobility of these ions inside the particles of chromium hexacyanoferrate(II) decrease in the order of Eu3+>Sr2+>Na+⊃Cs+. 相似文献
16.
Ion-exchange modification of MF-4SK perfluorosulfonic membranes with Eu3+ and Tb3+ cations was realized. The state of cations in the membrane was studied by X-ray photoelectron spectroscopy. Special features of the luminescence of the resulting systems point to preferential excitation energy transfer from europium to terbium. 相似文献
17.
Non-aggregated spherical polystyrene (PS) particles were coated with GdPO4:Tb3+/Ce3+ phosphor layers by a conventional hydrothermal synthesis using poly(vinylpyrrolidone) (PVP) as an additive without further
annealing treatment. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy
(TEM), photoluminescence (PL), as well as luminescence decay experiments were used to characterise the resulting core-shell
structured PS@GdPO4:Tb3+/Ce3+ samples. The results of XRD indicated that the PS particles were successfully coated with the GdPO4:Tb3+/Ce3+ phosphor layers, which could be further verified by the images of FESEM. Under ultraviolet excitation, the PS@GdPO4:Tb3+/Ce3+ phosphors show Tb3+ characteristic emission, i.e. 5D4-7FJ (J = {6, 5, 4, 3}) emission lines with green emission 5D4-7F5 (543 nm) as the most prominent group. The core-shell phosphors so obtained have potential applications in field emission
display (FED) and plasma display panels (PDP). 相似文献
18.
M. I. Ivanovskaya E. A. Ovodok D. A. Kotikov 《Russian Journal of General Chemistry》2011,81(10):2074-2079
A possibility was demonstrated of producing the chemical sensors based on Au-In2O3 obtained using a sol-gel technology. The sensors exhibit high sensitivity and selectivity toward CO. The differences in gas-sensitivity
properties of In2O3 sensor with respect to CO and CH4 at different ways of doping with Au(III) was examined. The effect of the gold nanoparticles size and the state of the indium
oxide surface on the characteristics of Au-In2O3 and Au/In2O3 sensors at the detection of CO and CH4 was examined. 相似文献
19.
Zinc gallate (ZnGa2O4) nanopowders doped with Cr3+ (1?mo%) were synthesized by the citric acid assisted sol–gel method. The influence of annealing temperature, structural, morphological, and optical properties of ZnGa2O4: Cr3+ (1?mol%) nanosized particles were investigated. The X-ray diffraction (XRD) spectra indicated that the nanoparticles are cubic in structure and the annealing temperature did not influence any c in structure. The average crystallite size of ZnGa2O4: Cr3+ nanoparticles were observed to increase from 11.85 to 30.88?nm as the annealing temperature increased from 600 to 1000?°C. The scanning electron microscopy (SEM) showed nearly spherical nanostructures that change in size with annealing temperature. The high resolution transmission electron microscope (HR-TEM) images show well resolved lattice fringes which is an indications of highly crystalline samples. Ultraviolet–visible (UV–Vis) measurement show decrease in reflectance in visible region and energy band gap was found to decrease with annealing temperature. The photoluminescence (PL) intensity was found to be maximum for sample annealed at high temperature (1000?°C) and least with sample annealed at low temperature (600?°C). An increase in annealing temperature leads significantly increment in PL intensity. The degree of crystallinity also increased with annealing temperature from XRD, SEM, and HR-TEM analysis. The photoluminescence lifetimes, particle size, and emission spectra are comparable with reports on bioimaging applications. 相似文献
20.
Catalytic performance of gallia-supported iridium catalysts in the reaction of selective hydrogenation of crotonaldehyde in the gas phase was studied and compared to that of platinum and ruthenium catalysts. The best catalytic properties in terms of the selectivity to crotyl alcohol are shown by 5 wt % Pt/α-Ga2O3 and 5 wt % Ir/α-Ga2O3 catalysts prepared from nonchlorine precursors: Pt(acac)2 and Ir(acac)3, but for the 5 wt % Pt/α-Ga2O3 a very high selectivity of 75% at the high conversion (ca. 60%) is observed. A high selectivity of galia-supported iridium and platinum catalysts was explained by the surface reducibility of gallium oxide leading to covering (decoration) of platinum and iridium by gallium suboxides and the promoting effect of gallium. 相似文献