共查询到20条相似文献,搜索用时 15 毫秒
1.
Guofeng Wang Weiping Qin Daisheng Zhang Guodong Wei Lili Wang 《Journal of fluorine chemistry》2009,130(8):755-758
One-dimensional BaSiF6:Yb3+(20%)/Tm3+(1.2%) nanorods were synthesized by a facile microemulsion method for the first time. X-ray topographic analysis found that the nanorods have a pure rhombohedral structure. Under 980 nm excitation, bright-blue upconversion luminescence was presented in the nanorods, indicating that BaSiF6 is a new host material for producing desirable upconversion luminescence. 相似文献
2.
Guofeng Wang Yue Xu Lili Wang Guodong Wei Peifen Zhu Ryongjin Kim 《Journal of fluorine chemistry》2008,129(11):1110-1113
The upconversion luminescent properties of YF3:Yb3+(20%)/Tm3+(1%) nanobundles with different sizes (240-500 nm in length) were studied under 980-nm excitation. Ultraviolet (1I6 → 3F4/3H6 and 1D2 → 3H6), blue (1D2 → 3F4 and 1G4 → 3H6), red (1D2 → 3H4, 1G4 → 3F4, and 3F3 → 3H6), and near infrared (3H4 → 3H6) emissions were observed. The results indicated that the relative intensity of the ultraviolet to the blue as well as the blue to the near infrared increased with decreasing the size of nanobundles. Especially, the position of the dominant red emission peak varied with the size of nanobundles. As the length of nanobundles increased to 500 nm, unusual 3F3 → 3H6 transition was observed, which was theoretically explained considering the decrease of the nonradiative transition rate of 3F3 → 3H4. 相似文献
3.
Chunyan Cao Weiping Qin Jisen Zhang Peifen Zhu Guodong Wei Longzhen Jin 《Journal of fluorine chemistry》2008,129(3):204-209
Tm3+/Yb3+ codoped rod-like YF3 nanocrystals were synthesized through a facile hydrothermal method. After annealing in an argon atmosphere, the nanocrystals emitted bright blue and intense ultraviolet (UV) light under a 980-nm continuous wave diode laser excitation. Up-conversion emissions centered at ∼291 nm (1I6 → 3H6), ∼347 nm (1I6 → 3F4), ∼362 nm (1D2 → 3H6), ∼452 nm (1D2 → 3F4), ∼476 nm (1G4 → 3H6), ∼642 nm (1G4 → 3F4), and ∼805 nm (3H4 → 3H6) were recorded using a fluorescence spectrophotometer. Especially, enhanced UV emissions were studied by changing Yb3+/Tm3+ doping concentrations, the annealing temperatures, and the excitation power densities. A possible mechanism, energy transfer-cross relaxation-energy transfer (ET-CR-ET), was proposed based on a simple rate-equation model to elucidate the process of the enhanced UV emissions. 相似文献
4.
ZHANG Ji-shuang QIN Wei-ping ZHANG Ji-sen WAN Yan CAO Chun-yan JIN Ye WEI Guo-dong WANG Guo-feng WANG Li-li 《高等学校化学研究》2007,23(6):214-735
Recently, considerable attention has been paid to the synthesis and research of various rare-earth (RE) doped fluoride nanomaterials because of their high refractive index and appropriate phonon energy, which have potential applications in optics, optoelectronics, microelectronics, and tribology. Many methods have been utilized to synthesize the nanomaterials of RE doped fluorides with controllable sizes, shapes, and nanostructures. Comparatively, the microwave irradiation (MWI) method is simple, fast, and unique in its potential for large-scale synthesis without suffering thermal gradient effects. 相似文献
5.
Guofeng Wang Jisen Zhang Yan Wang Lili Wang Peifen Zhu 《Journal of fluorine chemistry》2008,129(7):621-624
YF3:Eu3+ nanobundles were synthesized by a facile microemulsion method. Analysis of X-ray diffraction, scanning electron microscope, and transmission electron microscopy reveals that each nanobundle consists of numerous nanowhiskers with a mean length of ∼500 nm and a mean diameter of ∼2 nm. Under 393-nm excitation, the luminescence was dominated by 5D0 → 7F1 transition, indicating the inversion symmetry of Eu3+ site. The luminescence intensity increased with increasing Eu3+ concentration, up to about 30 mol%, and then decreased abruptly. The peak positions and spectral shapes of emissions were independent of Eu3+ concentration. Finally, the critical distance of energy transfer was calculated. 相似文献
6.
Polyol-mediated solvothermal synthesis and luminescence properties of CeF3, and CeF3:Tb nanocrystals
Xuesong Qu Hyun Kyoung Yang Byung Kee Moon Jung Hyun Jeong Kwang Ho Kim 《Journal of solid state chemistry》2011,184(2):246-251
CeF3 and CeF3:Tb3+ nanocrystals were successfully synthesized through a facile and effective polyol-mediated route with ethylene glycol (EG) as solvent. Various experimental techniques including X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and photoluminescence (PL) spectra as well as decay dynamics were used to characterize the samples. The results indicated that the content of NH4F and reactant concentrations were key factors in the product shape and size. Excessive NH4F was necessary for the formation of hexagonal nanoplates. The specific morphology of product can be controlled by changing the NH4F content and reactant concentrations. In addition, Tb3+ doped-CeF3 sample shows strong green emission centered at 544 nm corresponding to the 5D4-7F5 transition of Tb3+. Due to the decrease of nonradiative decay rate, the lifetime of 5D4 level of Tb3+ become longer gradually upon increasing the size of product. 相似文献
7.
不同形貌YF_3微米晶的水热合成及YF_3:Eu~(3+)荧光性质(英文) 总被引:2,自引:2,他引:0
水热条件下,Y(NO3)3·6H2O分别与K2SiF6、KPF6反应得到了不同形貌的YF3(八面体及椭球形)。以X射线光电子能谱(XPS)检测了产物的化学组成,表明产物中只含有Y和F。X射线衍射(XRD)结果表明所得的产物均为正交晶系。扫描电子显微镜(SEM)和透射电子显微镜(TEM)对产物的表征结果指明八面体形YF3棱长为200nm,而椭球形YF3是由小的纳米块自组装而成。还研究了Eu3+掺杂后YF3的荧光性质,并提出了可能的形成机理。 相似文献
8.
当使用液固溶法(LSS法)制备分散性纳米晶时,将传统油酸/油酸钠/酒精反应体系中的NaOH用氨水取代时,氨水将会与油酸形成新的表面活性剂油酸铵,这样就可以合成各种超细分散性的REF3纳米晶(RE代表稀土元素)。在这种新的反应体系中,合成了平均直径小于10 nm的YF3和GdF3超细颗粒,X射线与透射电镜测试表明YF3是正交相,而GdF3是面心立方结构,空间群为Fm3m,晶格常数为0.582 9 nm。在980 nm半导体激光器激发下,可检测到YF3∶Yb/Er在515~570 nm处有较强的绿色发光峰、645~675 nm处有较强的红色发光峰,呈橙色发光。YF3∶Yb/Tm和GdF3∶Yb/Tm样品在460~490 nm处有较强的蓝色发光峰,而在800 nm附近有更强的近红外发光峰。由于其超细的尺寸及红外上转换发光特性,合成的样品在生物成像、生物标签等方面有潜在的应用价值。 相似文献
9.
当使用液固溶法(LSS法)制备分散性纳米晶时,将传统油酸/油酸钠/酒精反应体系中的NaOH用氨水取代时,氨水将会与油酸形成新的表面活性剂油酸铵,这样就可以合成各种超细分散性的REF3纳米晶(RE代表稀土元素)。在这种新的反应体系中,合成了平均直径小于10nm的YF3和GdF3超细颗粒,X射线与透射电镜测试表明YF3是正交相,而GdF3是面心立方结构,空间群为Fm3m,晶格常数为0.5829nm。在980nm半导体激光器激发下,可检测到YF3:Yb/Er在515~570nm处有较强的绿色发光峰、645~675nm处有较强的红色发光峰,呈橙色发光。YF:Yb/Tm和GdF3:Yb/Tm样品在460~490nm处有较强的蓝色发光峰,而在800nm附近有更强的近红外发光峰。由于其超细的尺寸及红外上转换发光特性,合成的样品在生物成像,生物标签等方面有潜在的应用价值。 相似文献
10.
J. C. Boyer F. Vetrone J. A. Capobianco A. Speghini M. Bettinelli 《Chemical physics letters》2004,390(4-6):403-407
The effect of Yb3+ co-doping on the upconversion luminescence in nanocrystalline Gd3Ga5O12:Ho3+ was examined. Strong and efficient NIR to green anti-Stokes luminescence was noted in nanocrystalline Gd3Ga5O12:Ho3+, Yb3+ after excitation into the 2F5/2 level of Yb3+ with 978 nm radiation. Weaker blue, red and NIR anti-Stokes luminescence was also observed after 978 nm excitation. An enhancement of the red 5F5 → 5I8 luminescence was observed in the anti-Stokes spectrum compared to the Stokes emission spectrum. This enhancement was attributed to two distinct energy transfer upconversion (ETU) mechanisms which preferentially populate the (5F4, 5S2) and 5F5 levels. 相似文献
11.
The luminescent nanocrystalline Yb3+ and Er3+ codoped KLa(WO4)2 has been prepared by Pechini method. X-ray diffraction and transmission electron microscope were used to study the structure of the obtained samples. The average grain size of these samples depended on the annealing temperature, increasing with the increase of the temperature. The cell parameters and the crystallite size of KYbxEr0.02La0.98−x(WO4)2 nanocrystalline decreased with the increase of x value. Luminescence studies showed that the intensity of upconversion emission of the Yb3+ and Er3+ codoped samples was much stronger than that of the Er3+ single doped samples (pumped by 980 nm LD). The upconversion emission mechanisms suggested that all the three bands of upconversion emissions were two-photon process. 相似文献
12.
《印度化学会志》2023,100(5):100990
The emerging upconversion nanoparticles (UCNP) have gained substantial consideration in the field of bioanalytical as well as diagnostic applications. Therefore, great progress has been made in the synthesis and surface modification of luminescent UCNPs over the last two decades. In this paper, we have reported monodispersed and high luminescent upconversion nanoparticles NaYF4: 20%Yb3+, 2%Tm3+ have been synthesized using a solvothermal method, followed by a coating of the NaYF4 shell with a thin layer of SiO2 on the surface to afford the core-shell NaYF4:Yb3+, Tm3+@SiO2 nanoparticles (NP@SiO2). The prepared nanoparticles were of strong upconversion fluorescent emission intensity, hexagonal phase, and with an average size of about 8 ± 1 nm, which have been characterized by luminescence spectroscopy, powder X-ray diffraction (P-XRD), Dynamic light scattering (DLS), and Transmission electron microscopy (TEM). The results indicate that the NP@SiO2 can be used for the conjugation of fluorescent probes for various biomolecules and can find applications in cancer cell imaging and disease diagnosis. 相似文献
13.
Mohammad Asadi Mehdi Ghahari Seyed A. Hassanzadeh-Tabrizi Amir M. Arabi Rozita Nasiri 《中国化学会会志》2020,67(5):720-731
Synthesis, characterization, and in vitro toxicity evaluation of upconversion luminescence NaLuF4:Yb3+/Tm3+ nanoparticles (UCLNPs) are reported in the current study. Initially, the synthesized lanthanide trifluoroacetate (Ln(OOCCF3)3) precursor was used to fabricate NaLuF4 nanoparticles doped with Yb3+ and Tm3+ metal ions. The nanoparticles were coated with calcium carbonate (CaCO3) after removing the hydrophobic species on them to enhance their biocompatibility. The in vitro methylthiazolyldiphenyl-tetrazoliumbromide (MTT) test was used to evaluate the toxicity of synthesized NaLuF4:Yb3+/Tm3+ nanoparticles (NLF-5) on L929 mouse fibroblast cell lines. The transmission electron microscopy image showed that the particle size of NaLuF4:Yb3+/Tm3+ was 32 nm. The synthesized NLF-5 nanoparticles have both α-cubic and β-hexagonal crystalline structures that provided a superb near-infrared-to-near-infrared upconversion luminescence signal when excited at 980 nm. MTT test results show that the death of L929 fibroblast cells was observed only at concentrations above 250 μg/mL of NaLuF4:Yb3+/Tm3+ nanoparticles. In addition, with an increase in patrol time of 24, 48, and 72 hr, cell toxicity increased significantly, while the coated nanoparticles did not have any toxic effects. The synthesized nanoparticles could be used as a suitable material for medical applications due to their small particle size, high photoluminescence emission intensity, and low toxicity. 相似文献
14.
It is shown that the N-lines in the luminescence spectra of the two spinels ZnAl2O4:Cr3+ and MgAl2O4:Cr3+ exhibit quite similar dependencies on chromium concentration, excitation frequency, and thermal treatment of the samples. While most of these lines are structure dependent, the line N4 at and two very weak lines are in both cases due to chromium-pairs. The exchange Hamiltonian Hex = JS1 · S2 + j(S1 · S2)2 used for the ground-state splitting is fitted by the parameters J = 40.9 cm?1, j = 1.5 cm?1 and J = 45.6 cm?1, j = 2.0 cm?1 for ZnAl-spinel and MgAl-spinel, respectively. The differences between the spectra of low-doped and high-doped samples are in both cases caused by the existence of a phonon sideband of the N4-line, which is in many respects similar to the well-known phonon side band of the R-line. 相似文献
15.
Nanocrystalline YVO4:Eu3+ was synthesized by direct precipitation reaction, which was then annealed at different temperatures. The results of XRD showed that nanocrystalline YVO4:Eu3+ could be obtained in solution at 60 °C, and the mean particle sizes of samples are increased as annealing temperature is increased. The results of TEM exhibit that the sizes of samples are around 5-30 nm. Studies on the excitation spectra show that there are a large number of the structural distortions in smaller particles. By analyzing line splitting patterns and peaks broadening in the emission spectra, we consider that the deviations in intensity patterns of 5D0-7F2 are affected by distortions of crystal lattice. Some abnormal behaviors can be attributed to higher ratio of surface to volume, which lead to the different local symmetry environment of Eu3+ ions on the surface. 相似文献
16.
Zhang J Duan Z He D Dai S Zhang L Hu L 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(4-5):831-834
Up-conversion luminescence properties of a Tm3+/Yb3+ codoped oxyfluoride glass-ceramics under 980 nm excitation are investigated. Intense blue emission centered at 476 nm, corresponding to 1G4-->3H6 transitions of Tm3+ was simultaneously observed in the transparent oxyfluoride glass ceramics at room temperature. The intensity of the blue up-conversion luminescence in a 1 mol% YbF3-containing glass-ceramic was found to be about 40 times stronger than that in the precursor oxyfluoride glass. The reason for the intense Tm3+ up-conversion luminescence in the oxyfluoride glass-ceramics is discussed. The dependence of up-conversion intensities on excitation power and possible up-conversion mechanism are also evaluated. 相似文献
17.
Chu-Chi Ting Yi-Shan Chiu Chia-Wei Chang Liang-Chih Chuang 《Journal of solid state chemistry》2011,184(3):563-9
Er3+-doped Y2Ti2O7 nanocrystals were fabricated by the sol-gel method. While the annealing temperature exceeds 757 °C, amorphous pyrochlore phase ErxY2−xTi2O7 transfers to well-crystallized nanocrystals, and the average crystal size increases from ∼70 to ∼180 nm under 800-1000 °C/1 h annealing. ErxY2−xTi2O7 nanocrystals absorbing 980 nm photons can produce the upconversion (526, 547, and 660 nm; 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2, respectively) and Stokes (1528 nm; 4I13/2→4I15/2) photoluminescence (PL). The infrared PL decay curve is single-exponential for Er3+ (5 mol%)-doped Y2Ti2O7 nanocrystals but slightly nonexponential for Er3+ (10 mol%)-doped Y2Ti2O7 nanocrystals. For 5 and 10 mol% doping concentrations, the mechanism of up-converted green light is the two-photon excited-state absorption. Much stronger intensity of red light relative to green light was observed for the sample with 10 mol% dopant. This phenomenon can be attributed to the reduced distance between Er3+-Er3+ ions, resulting in the enhancement of the energy-transfer upconversion and cross-relaxation mechanisms. 相似文献
18.
Tb3+, Yb3+, Tm3+, Er3+, and Ho3+ doped Ca3(PO4)2 were synthesized by solid-state reaction, and their luminescence properties were studied by spectra techniques. Tb3+-doped samples can exhibit intense green emission under VUV excitation, and the brightness for the optimal Tb3+ content is comparable with that of the commercial Zn2SiO4:Mn2+ green phosphor. Under near-infrared laser excitation, the upconversion luminescence spectra of Yb3+, Tm3+, Er3+, and Ho3+ doped samples demonstrate that the red, green, and blue tricolored fluorescence could be obtained by codoping Yb3+-Ho3+, Yb3+-Er3+, and Yb3+-Tm3+ in Ca3(PO4)2, respectively. Good white upconversion emission with CIE chromaticity coordinates (0.358, 0.362) is achieved by quadri-doping Yb3+-Tm3+-Er3+-Ho3+ in Ca3(PO4)2, in which the cross-relaxation process between Er3+ and Tm3+, producing the 1D2-3F4 transition of Tm3+, is found. The upconversion mechanisms are elucidated through the laser power dependence of the upconverted emissions and the energy level diagrams. 相似文献
19.
采用直接沉淀法制备了WO_3/YF_3∶Eu~(3+)复合纳米材料,并对其结构、组成、形貌和发光性能进行了研究。XRD分析表明:复合纳米材料由纳米粒子WO3和结晶良好的正交晶系的YF3∶Eu~(3+)组成。SEM照片表明:片状WO3颗粒表面沉积了分散性较好、粒径均匀(尺寸为10~50 nm)的YF3∶Eu3纳米颗粒。荧光光谱分析表明:该复合纳米材料具有良好的发光性,以593 nm附近的5D0→7F1磁偶极跃迁为最强发射峰,与纯的YF3∶Eu~(3+)相比WO_3/YF_3∶Eu~(3+)发光强度明显增强,表明具有表面等离子共振效应的WO3纳米粒子对壳层的YF3∶Eu~(3+)起到发光增强作用。 相似文献
20.
Er-doped YF3 nanoparticles were prepared from quaternary microemulsions of cetyltrimethyl ammonium bromide, n-butanol, n-octane and water with oil to water(mass percent of ω(CTAB)=19.04%, ω(n-butanol)=15.24%, ω(n-octane)=51.40%. The nanofluorides were characterized by X-ray power diffraction and infrared fluorescence spectroscopy. The results of XRD are in agreement with the PDF#74-911 of YF3. The average grain size is about 30 nanometer as estimated by Scherrer Formula. ESEM images show that the diameter of BaF2∶Er3+ nanoparticles is 35 nm. The emission of infrared fluorescence spectroscopy of the predominant peak is located at 1 547 nm and the up-conversion optical properties measured with 980 nm laser diode show red and green emissions. 相似文献