Time filter

Source Type

Shan W.,Hunan University | Shan W.,Hunan Provincial Key Laboratory for Cost effective Utilization of Fossil Fuel Aimed at Reducing Carbon dioxide Emissions | Wu L.,Hunan University | Tao N.,Hunan University | And 3 more authors.
Ceramics International | Year: 2015

A kind of Eu2+ and Dy3+ co-doped strontium aluminate green long-lasting phosphor was synthesized via a coprecipitation synthesis method assisted by microwave irradiation in a weak reductive atmosphere of active carbon. The synthesis conditions were optimized with orthogonal experiments and the optimum technological parameters were obtained. Subsequently, the crystal structure, morphology and optical property of the composites were characterized. X-ray diffraction (XRD) patterns illustrated that the samples were composed of single-phase SrAl2O4. Scanning electron microscopy (SEM) revealed that the resultant nanoparticles had well-dispersed distribution and flake-like morphology with an average size of about 500nm in width and 70nm in thickness. The excitation and emission spectra indicated that excitation broadband chiefly lied in the ultraviolet range and naocrystalline particles emitted strong light at 508nm corresponding to the typical characteristic 5d-4f transition of Eu2+ ion under around 325nm excitation. And the long afterglow photoluminescence of SrAl2O4:Eu2+,Dy3+ was observed in the dark with the naked eye after the removal of the excitation light. Furthermore, the microwave method requires a very short heating-time and the energy consumption. © 2015 Elsevier Ltd and Techna Group S.r.l.


Yan D.,Hunan University | Xiang Y.,Hunan University | Li K.,Hunan University | Chen Y.,Hunan Labour Protection Institute of Nonferrous Metals | And 2 more authors.
Journal of Molecular Structure | Year: 2014

Eight novel 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole derivatives and their corresponding Eu(III) complexes were synthesized and characterized. From the spectral studies it has been concluded that the title Eu(III) complexes display six coordination. The investigation of the luminescence properties of the title complexes showed that the ligands favor energy transfers to the emitting energy level of europium ions. The title Eu(III) complexes exhibited characteristic emissions of europium ions, and possessed strong luminescence intensities, good fluorescence quantum yields, and the highest fluorescence quantum yield is up to 0.522. Furthermore, the luminescence intensity of the complex with chlorine-substituted group is the strongest than that of other complexes. The exploration of the electrochemical properties of the title complexes shows that the introduction of electron-donating groups can increase the HOMO energy levels, LUMO energy levels and the oxidation potential of the complexes, however, the result of introduction of electron-withdrawing groups was just opposite. © 2014 Elsevier Ltd. All rights reserved.


Shan W.,Hunan University | Liu F.,Hunan University | Liu J.,Hunan University | Chen Y.,Hunan Labour Protection Institute of Nonferrous Metals | And 2 more authors.
Journal of Inorganic Biochemistry | Year: 2015

Four novel salicylaldehyde isonicotinoyl hydrazone derivatives and their corresponding europium ion complexes were synthesized and characterized, while the luminescence properties and the fluorescence quantum yields of the target complexes were investigated. The results indicated that the ligands favored energy transfers to the emitting energy level of europium ion, and four target europium complexes showed the characteristic luminescence of central europium ion. Besides the luminescence intensity of the complex with methoxy group, which possessed the highest fluorescence quantum yield (0.522), was stronger than that of other complexes. Furthermore, the electrochemical properties of the target complexes were further investigated by cyclic voltammetry, the results indicated that the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) energy levels and the oxidation potential of the complexes with electron donating group increased, however, that of the complexes with accepting electron group decreased. © 2015 Elsevier Inc.


Liu Y.,Hunan University | He W.,Hunan University | Yang Z.,Ningbo University of Technology | Chen Y.,Hunan Labour Protection Institute of Nonferrous Metals | And 3 more authors.
Research on Chemical Intermediates | Year: 2016

Amide-type podands derived from N,N′-(ethane-1,2-diyl)bis(2-hydroxybenzamide) and 2-chloro-N-phenylacetamide (substituted with methyl, methoxy, chlorine, nitrogen) were synthesized. Solid complexes of europium nitrate with podands were also synthesized and characterized by elemental analysis, ethylenediaminetetraacetic acid (EDTA) titrimetric analysis, thermal analysis, molar conductivity analysis, and infrared (IR) and ultraviolet-visible (UV-Vis) spectra analysis. The fluorescent properties of the europium(III) [Eu(III)] complexes in a solid state were also investigated. Under excitation of UV light, target Eu(III) complexes exhibited characteristic europium ion emissions. The influence of the substituent on the fluorescence intensity was discussed. Electrochemical properties were also investigated and discussed. © 2015 Springer Science+Business Media Dordrecht.


Liu Y.,Hunan University | He W.,Hunan University | Yang Z.,Ningbo University of Technology | Chen Y.,Hunan Labour Protection Institute of Nonferrous Metals | And 2 more authors.
Journal of Luminescence | Year: 2015

Six amide-based open-chain crown ether and their solid complexes with terbium nitrates were synthesized. The target complexes were characterized by elemental analysis, mass spectra, EDTA titrimetric analysis, thermal analysis, molar conductivity, infrared spectra and UV-vis spectra. Luminescence properties of the ligands and the corresponding complexes in solid were studied. The results showed that the introduction of electron-donating group to the ligand enhanced the luminescence intensity of the corresponding complex, but electron-withdrawing group conversely. Meanwhile, among all complexes, the luminescence quantum yield of the complex Tb(NO3)3Y1 was highest up to 0.76. Electrochemical properties were also investigated, and the results showed that the introduction of electron-donating group to the ligand enhanced the highest occupied molecular orbit (HOMO) and the lowest unoccupied molecular orbit (LUMO) energy level, but electron-withdrawing group conversely. And these target complexes may possibly be useful for studying in organic light-emitting devices field. © 2014 Elsevier B.V. All rights reserved.


Shan W.,Hunan University | Li R.,Hunan University | Feng J.,Hunan University | Chen Y.,Hunan Labour Protection Institute of Nonferrous Metals | Guo D.,Hunan University
Materials Chemistry and Physics | Year: 2015

An up-conversion luminescent material, NaYF4 doped with rare-earth (RE), possessed a high luminescence efficiency and excellent stability. As described herein, a series of hexagonal nano-prismatic NaYF4:Yb3+,Tm3+ up-conversion phosphors had successfully been synthesized through mild hydrothermal method. The influence of hydrothermal time, the content of sodium tartrate, activator, sensitizer and ammonium fluoride on the luminescence properties of the target product were systematically investigated by means of single factor experiments. Based on the single factor experiments, the orthogonal method was used to obtain the optimal preparation conditions of the sodium tartrate/RE mole ratio, the sensitizer Yb3+ ions content, the NH4F/RE mole ratio, and the hydrothermal time which were 0.5, 23%, 11, 13h, respectively. The fluorescent emission spectra analysis results showed that the strongest blue up-conversion luminescence emission peaks (1G4→3H6 transition of Tm3+ ion) of the NaYF4:Yb3+,Tm3+ phosphors using sodium tartrate as complexing agent was located at 477nm under 980nm near infrared (NIR) laser diode excitation. Finally the target products using different complexing agent were prepared at optimum preparation condition, and characterized by X-ray diffraction, scanning electron microscope. The crystal structure of products using tartaric acid and citric acid as complexing agent was hexagonal, consisting of spheres with 100nm diameter. © 2015 Elsevier B.V.


Du H.,Hunan University | Shan W.,Hunan University | Wang L.,Hunan University | Xu D.,Hunan University | And 4 more authors.
Journal of Luminescence | Year: 2016

A novel Eu2+-Dy3+co-doped strontium aluminate green long-lasting phosphors were synthesized via conventional sol-gel method with citric acid and polyethylene glycol used as chelating agent, respectively. Orthogonal experiments were employed to optimize the main synthesis conditions and obtain the optimum technological parameters. Subsequently, the crystal structure, morphology, decay curve and luminescence property of the composites were characterized. X-ray diffraction (XRD) showed that the samples were composed of single-phase SrAl2O4. Scanning electron microscopy (SEM) revealed that the resultant nanoparticles performed graininess with a size of 100 nm around. The excitation and emission spectra indicated that, excitation broadband chiefly lay in the ultraviolet range, and nanocrystalline particles emitted strong light at 510 nm, which corresponding to the typical characteristic 5d-4f transition of Eu2+ ion excited at around 360 nm. The long afterglow photoluminescence of nanoparticles SrAl2O4: Eu2+, Dy3+ (denoted as SAO: ED) was observed in the dark with the naked eye even after the removal of the excitation light. The luminescence properties suggested that SAO: ED phosphor may be regarded as a potential green phosphor candidate for near-UV and blue light-emitting diodes (LEDs). © 2016 Elsevier B.V. All rights reserved.

Loading Hunan Labour Protection Institute of Nonferrous Metals collaborators
Loading Hunan Labour Protection Institute of Nonferrous Metals collaborators