共查询到20条相似文献,搜索用时 15 毫秒
1.
《Materials Research Bulletin》2006,41(1):191-197
Fine powders of Y2Sn2O7 nanocrystals with pyrochlore structure have been successfully synthesized by the hydrothermal method in an alkaline system. The samples were characterized by X-ray diffraction, Fourier transform infrared and Raman spectroscopy. Furthermore, photoluminescence characterization of the Y2Sn2O7 nanocrystals doped with 5 mol% Eu3+ was carried out, and the results show that there were some intense and prevailing emission peaks located at 580–635 nm. 相似文献
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Luo L Huang FY Guo GJ Tanner PA Chen J Tao YT Zhou J Yuan LY Chen SY Chueh YL Fan HH Li KF Cheah KW 《Journal of nanoscience and nanotechnology》2012,12(3):2417-2423
Successful doping of Eu3+ ions into ZnO nanocrystals has been realized by using a low temperature wet chemical doping technique. The substitution of Eu3+ for Zn2+ is shown to be dominant in the Eu-doped ZnO nanocrystals by analyzing the X-ray diffraction patterns, transmission electron microscopy images, Raman and selectively excited photoluminescence spectra. Measurement of the luminescence from the samples shows that the excited ZnO transfers the excited energy efficiently to the doped Eu3+ ions, giving rise to efficient emission at red spectral region. The red emission quantum yield is measured to be 31% at room temperature. The temperature dependence of photoluminescence and the photoluminescence excitation spectra have also been investigated, showing strong energy coupling between the ZnO host and Eu3+ ions through free and bound excitons. The result indicates that Eu3+ ion-doped ZnO nanocrystals are promising light-conversion materials and have potential application in highly distinguishable emissive flat panel display and LED backlights. 相似文献
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《Materials Letters》2004,58(7-8):1172-1175
The preparation and luminescent properties of Eu3+-doped zinc sulfide nanocrystal were investigated. The best reactive conditions were determined, such as the concentration of reactants, the kinds and amount of the surfactants, the reaction temperature and reaction time, the pH, the flowing speed and pressure of reactive gases. The crystal structure of the nanocrystal powders was tested by X-ray diffraction (XRD). The emission and excitation spectra of ZnS:Eu were characterized by fluorescent divide spectroscopy (FDS). The luminescent sites and their strength as a function of doping Eu3+ ions are discussed. 相似文献
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Water-soluble and amino-functionalized luminescent Dy3+-doped BaFCl nanocrystals have been synthesized for the first time via a facile one-step modified solvothermal method with polyethyleneimine (PEI) as capping agent. The obtained BaFCl:Dy3+ nanocrystals have a size of about 40 nm, remain stable in aqueous solutions under different pH, and exhibit intense visible luminescence of Dy3+. The synthesized nanocrystals featuring long-lived luminescence may have potential applications as time-resolved photoluminescent probes for bio-applications. 相似文献
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纳米晶MnFe2O4的水热法合成及其磁性能 总被引:1,自引:0,他引:1
采用水热法制备了软磁材料MnFezO4纳米晶,借助XRD、IR、SEM和VSM对产物进行了表征,着重研究了水热条件如温度和时间等对MnFe2O4纳米晶的形成及其结构和磁性能的影响。结果表明水热温度较低时的产物晶化度和纯度低,表现出较差的磁性能,温度为120℃的产物其饱和磁化强度为15.34emu/g,剩磁比为0.08,矫顽力为8lOe,而在200℃下水热产物饱和磁化强度为51.49emu/g,剩磁比达到0.14,矫顽力为121Oe。 相似文献
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Liu F Shao X Yin Y Zhao L Jia Z Sun Q Shao Z Liu X Meng X 《Journal of nanoscience and nanotechnology》2011,11(11):9684-9689
Eu3+-doped REVO4 nanphosphors were controllably synthesized by an EDTA-mediated hydrothermal method at 180 degrees C using RE(NO3)3 and Na3VO4 as precursors. The obtained products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectra (XPS), and photoluminescence spectroscopy (PL). The XRD results showed that the products were pure tetragonal structure and no other impurity phase appeared. The PL studies demonstrated Eu3+ ions doping effectively enhanced luminescent properties of LaxRE(1-x)VO4 and YxRE(1-x)VO4 nanoparticles, but EU3+ ions doping did not enhance luminescent properties of CexRE(1-x)VO4 (x not equal 0) nanoparticles. The prepared phosphors showed well-defined red luminescence due to radiative transitions from 5D0 to 7F(J) (J = 1,2) levels of Eu3+ ions, respectively. Furthermore, we reported Eu3+-doped CexRE(1-x)VO4 (x not equal 0) phases represented a new class of optically inactive materials. 相似文献
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《Journal of Experimental Nanoscience》2013,8(4):301-311
Eu3+-doped GdVO4 has been synthesised via hydrothermal method by altering the hydrothermal temperature, reaction time and surfactant. The microstructure and morphology information of the phosphors were investigated via the techniques of X-ray powder diffraction and scanning electronic microscopy, which show that the phosphors wear tetragonal phase and the products present various regular morphologies under different reaction conditions such as bulk and nanoparticle. Moreover, the morphologies of the products have been controlled by altering reaction temperature. In addition, the surfactant was also included to control the morphologies of the products and the phosphors present different morphologies. All the phosphors exhibit the characteristic fluorescence of Eu ion (5D0 → 7F2 and 5D0 → 7F2). The electric dipole transition 5D0 → 7F2 of Eu3+ is dominant indicating that most sites of Eu3+ ions in GdVO4 have no inversion centre. Furthermore, we found that the reaction time and the morphologies have great influence on optical properties. 相似文献
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Surface doping of oxide nanoparticles is important in fields ranging from heterogeneous catalysis to optoelectronics. Here, we report the solvent-free synthesis of mixed calcium-magnesium oxide nanocrystals in the size range between 5 and 40 nm. Although CaMgO mixtures are thermodynamically forbidden on a macroscopic scale, Calcium ions can be distributed homogeneously in MgO using chemical vapor deposition (CVD) as a nonequilibrium technique. Subsequent thermal activation leads to calcium ion segregation into the nanocrystal surface which, in addition to the synthesis parameters, provides efficient means for manipulating the optical surface properties of insulating oxide nanocrystals. A novel material with unexpected photonic behavior, such as enhanced photoluminescence emission which is also red-shifted with respect to those of CaO and MgO, was found. 相似文献
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Uniform monoclinic core-shell and hexagonal urchin-like LaPO4:Eu(3+) spheres are synthesized via an attractive hydrothermal method owing to the higher yield and simplicity. Photoluminescence and Raman spectra of two samples have been investigated under high pressure up to 28 GPa using diamond anvil cells. At ambient pressure, both samples exhibit same luminescent properties with that of bulk monazite LaPO4:Eu(3+). With the increase of pressure, the emission intensity of Eu(3+) decreases and the half-widths of transition lines increase for both samples, while emission peaks show a red shift toward longer wavelengths due to increase in both the crystal-field strength and the covalency. Monoclinic core-shell LaPO4:Eu(3+) becomes amorphous finally while hexagonal urchin-like one transforms to monoclinic structure at lower pressure of 3.2 GPa and turns into amorphous structure at higher pressures, which are presented based on the analysis of high pressure Raman spectra. 相似文献
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采用水热法添加醋酸钠制备了纳米羟基氧化镓(GaOOH)粉体和纳米GaOOH:Eu3+荧光粉,使用透射电镜(TEM)、扫描电镜(SEM)、X射线衍射仪(XRD)和荧光分光光度计对产物的形貌、晶相和发光性质进行了检测,结果发现醋酸钠(NaAc)在控制晶体粒径和形貌方面起到了非常重要的作用。在140℃水热条件下,未添加醋酸钠下得到的是纺锤体GaOOH,添加醋酸钠得到的是立方体块状GaOOH,在170℃水热条件下,添加醋酸钠得到的是纳米GaOOH粉体,平均粒径约为5nm,并简单讨论了不同形貌GaOOH的生长机制。比较不同温度添加醋酸钠制备的GaOOH:Eu3+荧光粉的发光性质发现,170℃得到的GaOOH:Eu3+发光强度140℃的样品,不同掺杂浓度发光性能结果表明Eu3+浓度为10%(摩尔分数)发光强度最高,是已报道的掺杂浓度的4倍,在掺杂浓度为15%(摩尔分数)观察到了浓度猝灭现象。 相似文献
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《Materials Research Bulletin》2006,41(3):642-646
Eu3+-doped LaPO4 nanocrystals were synthesized for the first time by a combustion method with urea as a fuel calcined at 700 °C. The diffraction profile of the obtained sample was indexed as a monoclinic monazite-structure by X-ray diffraction (XRD) data. The obtained nanocrystals appeared to be short rod-like with diameters of 5–10 nm and lengths of 20–70 nm. The luminescence intensities of Eu3+-doped LaPO4 nanocrystals were found to be strongly dependent on the quantities of urea added and the concentration of Eu3+. 相似文献
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Hydrothermal synthesis and optical properties of CuS nanoplates 总被引:1,自引:0,他引:1
Jie Zhang 《Materials Letters》2008,62(15):2279-2281
CuS nanoplates have been successfully prepared in the presence of cation surfactant cetyltrimethylammonium bromide (CTAB) by hydrothermally treating the solution of CuCl2·2H2O and Na2S·9H2O at 180 °C for 24 h. The as-prepared CuS nanoplates are of hexagonal phase and are single crystal. The thickness and edge length of the nanoplates are about 15 nm and 60 nm, respectively. The products was characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, photoluminescence measurements and ultraviolet-visible light spectrophotometer. The influences of synthetic parameters, such as reaction time and CTAB, on the morphologies of the products have been investigated. 相似文献
16.
Tian Y Chen B Hua R Sun J Cheng L Zhong H Li X Zhang J Meng Q Chen M 《Journal of nanoscience and nanotechnology》2011,11(11):9631-9635
In this paper, a two-step synthesis method for preparing Eu3+ ion-doped Y2O3@YOF core-shell nanocrystals is introduced. Eu3+ ion-doped Y2O3@YOF core-shell nanocrystals were prepared by combining an autocombustion process with a low temperature solid state reaction. X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), photoluminescence (PL) and fluorescence decay were employed to characterize the prepared samples. The results of XRD, TEM and EDS indicated that the products prepared by this method were not a mixture of Y2O3:Eu3+ and YOF:Eu3+ nanocrystals, but Eu3+ ion-doped Y2O3@YOF core-shell nanocrystals. Compared with Y2O3:Eu3+ nanocrystals, a 20% increment in luminescence intensity was observed in the Eu3+ ion-doped Y2O3@YOF core-shell nanocrystals, thus suggesting that coating with a YOF:Eu3+-shell can efficiently block the nonradiative relaxation channels that are induced by surface defect states. 相似文献
17.
Xiaoqi Xing Dongyi Ling Lin Tan 《Journal of Materials Science: Materials in Electronics》2014,25(11):4774-4778
CaSiO3:(Eu2+, Dy3+) nanorods were synthesized by microwave irradiation process with assistant of polyethylene glycol (PEG)-1000. The X-ray diffraction results show that the obtained samples are of β-CaSiO3 phase with perovskite structure. The TEM images show that the obtained samples are of nanorods with diameter around 40 nm and length ranging from 0.6 to 1.2 μm. PEG-1000 plays an important role in the formation of claviform morphology. The excitation and emission spectra of CaSiO3:(Eu2+, Dy3+) samples show characteristic transitions of Eu2+ ions. All samples give a green emission peaked at 512 nm when they are excited at 366 nm. The co-doped Dy3+ ions enhance the luminescence intensity greatly but have no obvious influences on location of emission peak. CaSiO3:(0.05Eu2+, 0.03Dy3+) samples give the highest luminescence intensity. 相似文献
18.
The branch-shaped NaGdF4:Eu3+ nanocrystals (NCs) were synthesized by using polyvinylpyrrolidone (PVP) as a capping agent in ethylene glycol (EG) solution. The NCs were readily dispersed into water or ethanol to form a relatively stable suspension, which may facilitate their applications in biological fields. Meanwhile, the crystal structures of the NCs were tunable from the mixture of the α-(cubic) and β-(hexagonal) phases to the pure β-phase by varying the F?/Ln3+ molar ratio or the reaction temperature. The pure β-phase NCs were obtained at relatively high F?/Ln3+ molar ratio and reaction temperature. In addition, the Eu3+-doping concentration—dependent optical properties of the NaGdF4:Eu3+ NCs were investigated in detail. The result shows that the emissions from high energy level transitions (e.g., 5D1, 5D2, and 5D3) are significantly impaired with increasing the Eu3+-doping concentration due to the cross-relaxation process, and the emission at 612 nm is predominant since the doped Eu3+ ions locate in the crystal fields without inversion center. 相似文献
19.
Taehyung Kim 《Materials Research Bulletin》2005,40(11):1945-1954
Nano-crystalline GdBO3:Eu3+ was prepared by a hydrothermal method and the effects of some processing variables such as pH, temperature were investigated. The as-synthesized powders were spherical shaped agglomerates of nanoparticles. The luminescent properties were compared with samples synthesized by conventional solid-state reaction method. Both the photoluminescence intensity and chromaticity were improved and a red-shift in the CT band was observed for the hydrothermally synthesized samples. Possible mechanisms of phase formation were investigated and explanations for the changes in optical properties are proposed. 相似文献