最新刊期
卷 32 ， 期 5 ， 2011
- 摘要：Ce3+ activated phosphors, fluorophosphate Na2Gd0.99Ce0.01PO4F2 and polyphosphates MGd0.99-Ce0.01(PO3)4 (M=Na,K,Cs), were prepared using a high-temperature solid-state reaction technique. Five excitation bands were observed at about 316, 266, 235, 216, 206 nm from Ce3+ 5d in Na2Gd0.99Ce0.01PO4F2, and two emission bands from Ce3+ 5d-4f were found at about 350, 375 nm. On the basis of these observations, it is assumed that Ce3+ ions occupy one lattice site in Na2Gd0.99Ce0.01PO4F2. The luminescence of MGd0.99Ce0.01(PO3)4 (M=Na,K,Cs) under X-ray excitation revealed that these phosphors have high light-yields under X-ray excitation, showing that they may be potential scintillation materials.关键词：Ce3+;fluorophosphate;polyphosphate;luminescence145|123|5更新时间：2020-08-12
- 摘要：Triply doped Y3Al5O12 ∶ Ce3+, Pr3+, Cr3+ phosphors with Ce3+ and Pr3+ substituting for Y3+ sites and Cr3+ substituting for Al3+ site are prepared by solid state reaction. A broad emission spectrum composed a yellow emission band from Ce3+, a light red emission line from Pr3+ and a deep red emission line from Cr3+, which are generated through energy transfer among the dopant ions. The study of photoluminescence and fluorescence decay indicates that there exist energy transfers from Ce3+→Cr3+ and Ce3+→Pr3+→Cr3+ . The effect of energy transfer on relative intensities of the three emissions is analyzed. A white LED is fabricated using a blue LED chip coated with the triply doped phosphor and shows a color rendering index of 81.4 and 80.4, respectively.It is higher than that either using Ce3+ and Cr3+ doubly doped phosphor or Ce3+ singly doped phosphors.关键词：YAG;energy transfer;WLED139|73|3更新时间：2020-08-12
- 摘要：Using zinc acetate dihydrate and sodium hydroxide as starting materials, ZnO nanorods with narrower size distribution were prepared via a H2O2-assisted hydrothermal process. The samples are characterized by means of XRD, FTIR, FESEM, HRTEM and SAED. The results show that the samples are single crystalline in nature. All of the nanorods have hexagonal cross sections and grow along the [0001] crystallographic direction. The room temperature photoluminescence (PL) measurement results show that the UV emission intensity at 390 nm of the as-obtained nanorods with H2O2 increases significantly,while the green emission at 558 nm is suppressed. The addition of H2O2 can modulate the nucleation and the growth rate of ZnO crystal.关键词：ZnO;characterization;H2O2;hydrothermal method165|101|3更新时间：2020-08-12
- 摘要：ZnTe nanopowder was synthesized at 160 ℃ by hydrothermal method, in which the zinc and tellurium powders were used as the precursors. The powder was characterized by X-ray diffraction, X-ray energy dispersive spectroscopy, transmission electron microscopy and micro-Raman spectroscopy. The X-ray diffraction pattern indicates that the synthesized ZnTe particles are zinc blend structure. The X-ray energy dispersive spectrum exhibits that the main elements in the ZnTe nanopowder are zinc and tellurium and the impurity is oxygen. The image of transmission electron microscopy shows that the particles in the powder are diversified in size ranging from about 8 to 160 nm and the small particles aggregate easily. Raman spectrum shows there are three longitudinal optical phonon vibration modes of ZnTe centered at about 206,411,615 cm-1. The photoluminescence of ZnTe nanopowders was investigated at room temperature. The photoluminescence spectrum shows the weak recombination emission of donor-acceptor pairs presented at about 535.6 nm and the strong emission bands related to the complex defects containing Zn vacancies and impurity as well as isoelectronic oxygen trap at about 581,699 nm, respectively. The recombination emission of donor-acceptor pairs at room temperature is reasonably explained by the related theory.关键词：hydrothermal method;ZnTe nanopowder;Raman spectrum;photoluminescence112|132|0更新时间：2020-08-12
- 摘要：A series of holmium ions doped borosilicate glass, including Ho3+-doped, Ho3+ /Er3+-doped, Ho3+ / Yb3+-doped and Ho3+ /Yb3+ /Er3+-doped galss, have been prepared by high-temperature melting. The up-conversion excitation spectra and emission spectra of the samples decrease. The analysis result reveals that both the intensities of excitation spectra and emission spectra were weaken with the Ho3+concentration. The spectral intensities of Ho3+/Yb3+-doped borosilicate glass increase with the increase of Ho3+concentration because of the sensitization of Yb3+. The excitation and emission spectra intensities of Ho3+/Yb3+/Er3+-doped borosilicate glass are weak, and the reason is the energy transfers from Ho3+ ions to Er3+ ions through energy resonant transfer process. Meanwhile the luminescence mechanism of broadband emission peaked at 550 nm is analyzed.关键词：Ho3+ /Yb3+ /Er3+co-doped borosilicate glass;excitation spectra;emission spectra166|109|2更新时间：2020-08-12
- 摘要：Eu2+ doped Ba5-xSrx(PO4)3Cl(x=0,1,2,3,4,5)blue phosphors particle were prepared by the conventional solid-state reaction method. It can be clearly exhibited that XRD peaks of the samples shift to the smaller angle side with the increasing content of Ba2+.In excitation spectra, two peaks fell toward each other of all the samples and their intensities decreased with increasing content of Ba2+, which can be explained by the configuration-coordinate model. Seen from the emission spectra, the position of the emission peaks did not change with the excitation wavelengths, which indicated that two emission peaks did not come from two different sites of Eu2+ ions. It can be attributed to two Stark levels of 4f65d1 configuration. The broader emission bands can be attributed to the increase of inhomogeneous line width from changed crystal field by introducing Ba2+ ions. The excitation and emission spectra show that Eu2+ doped Ba3Sr2(PO4)3Cl is a promising blue phosphor for ultraviolet light emitting diode (LED).关键词：LED;phosphor;emission104|108|0更新时间：2020-08-12
- 摘要：Lu modified (Ca2.94-xLuxCe0.06)(ScMg)Si3O12 (CLSMS ∶ Ce3+) yellow emitting phosphors are prepared by solid-state reaction. The effects of Lu content on crystal phase formation, luminescence properties and temperature characteristics are studied. It is revealed that the Lu induced luminescent enhancement can be attributed to the increase of absorbance of Ce3+ rather than the internal quantum efficiency. Intense and broadband emission is realized by controlling the Lu content to obtain a pure CLSMS crystal phase. The maximum luminescence intensity is obtained at x=0.54, which is as high as 156% of the Lu free phosphor. Combining the present phosphor with a blue LED chip, a white LED with an excellent color rendering index of 86 and high luminous efficiency of 86 lm·W-1 is obtained.关键词：yellow phosphor;silicate;white LED151|40|3更新时间：2020-08-12
- 摘要：The photoluminescence properties of Y2-x (W,Mo)O6 ∶ Eu3+, xLi+ were investigated in this paper. The excitation spectra of Y2(W,Mo)O6 ∶ Eu3+ showed two broad excitation bands at 290 and 368 nm which were attributable to the O2- → W6+ and O2- → Mo6+ transitions, respectively. The excitation band edge moved from 370 nm to 450 nm with the incorporation of Mo6+ ions. The emission spectra exhibited two weak lines at 588, 593 nm owing to the 5D0 → 7F1 transition, and strong sharp peak at about 610 nm owing to the5D0 → 7F2 transition of the Eu3+ ion. Moreover, the bluish-green luminescence of the WO6-6 group corresponding to the 3T1u→1A1u transition was also observed in these compounds. The emission of the WO6-6 decreases with the increasing concentration of Mo6+ in Y2(W,Mo)O6 ∶ Eu3+ due to the energy transfer with the process WO6-6→MoO6-6. As a result, pure red color emission was obtained with the incorporation of Mo6+ ions. However, the emission intensities of Y2(W,Mo)O6 ∶ Eu3+ decreased with incorporation of Mo6+ ions. In order to enhance the emission intensities of Y2(W,Mo)O6 ∶ Eu3+, Li+ ions were introduced into Y2(W,Mo)O6 ∶ Eu3+. The red luminescence of Eu3+ in Y2(W,Mo)O6 was greatly enhanced after codoping monovalent alkali metal ions Li+ into the lattice. The morphology of powder particles was characterized by scanning electron microscope. The incorporation of Li+ increased the particle grain size. The hexagonal crystalline of the Y2(W,Mo)O6 ∶ Eu3+, Li+ powder had a preferred growth orientation. It was speculated that the Li+ ions may serve as a selfpromoter for better crystallization or as a lubricant for the complete incorporation of the Eu3+ ions into the host lattice, and it resulted to the enhancemednt of PL of Y2(W,Mo)O3 ∶ Eu3+.This study showed that the red phosphor, Y2(W,Mo)O6 ∶ Eu3+ incorporated with Li+ ions was advantageous for LEDs application.关键词：white LED;solid state solution;Y2-x(W;Mo)O6 ∶ Eu3+;xLi+102|91|1更新时间：2020-08-12
- 摘要：Rare earth ion doped phosphors have attracted great interest during the past several decades due to their unique physical and chemical properties. Among these rare earth ions, the Eu3+ ion can emit red fluorescence centered at around 613 nm, corresponding to the 5D0→7F2 transition. Thus many Eu3+-doped materials can be used as red phosphors for white LEDs. In this paper, the Eu3+ and Sm3+ co-doped CaMoO4 red phosphors were synthesized using a coprecipitation method. The effect of Sm3+ doping on structural and luminescent properties of CaMoO4 ∶ Eu3+ red phosphors were studied. The results indicate that the particle size of the samples decrease with Sm3+ doping concentration. The excitation intensity at around 405 nm and emission intensity at around 613 nm of Eu3+ increased after the introduction of Sm3+ ions. When the mole fraction of Sm3+ is 5%, the emission intensity of red light is the strongest. In addition, the chromaticity coordinates for CaMoO4 ∶ 0.1Eu3+ and CaMoO4 ∶ 0.1Eu3+, 0.05Sm3+ phosphors are (0.661,0.329) and (0.667,0.328), respectively. The chromaticity coordinates of CaMoO4 ∶ 0.1Eu3+, 0.05Sm3+ phosphors is closer to the Commission International del Eclairage (CIE) chromaticity coordinates(0.67,0.33). In conclusion, the Eu3+ and Sm3+ co-doped CaMoO4 is a high performance red phosphor and has a potential application in white light emitting diodes.关键词：CaMoO4 ∶ Eu3+ red phosphors;white LED;Sm3+ ion;coprecipitation method171|100|7更新时间：2020-08-12
- 摘要：Aligned ZnO nanowires (NWs) were obtained by hydrothermal method using annealed ZnO film as seed layer.Besides Si(400), only ZnO(002) diffraction peak was observed in X-ray diffraction(XRD) pattern. The lasing emissions were observed in optically pumped aligned ZnO NWs. Multi-mode emission peaks emerged when the excitation power density exceed the threshold.The integrated intensity of the spectra increases nonlinearly with the excitation power density, and the transition point from the spontaneous emission to lasing at about 96 kW/cm2 can be clearly observed.关键词：lasing;ZnO;aligned nanowires107|113|1更新时间：2020-08-12
- 摘要：LaPO4 ∶ Eu3+ luminescence nanorods were prepared via a hydrothermal method without any surfactants, then an uniform SiO2 layer was coated on the surface of LaPO4 ∶ Eu3+ nanorods by sol-gel method. At lasts LaPO4 ∶ Eu3+@SiO2 core-shell structural luminescence nanorods were achieved. XRD patterns show that the uncoated and coated samples are all monclinic LaPO4 crystals. FTIR spectra indicate that LaPO4 ∶ Eu3+ is linked with SiO2 by chemical bond. TEM images reveal that the LaPO4 ∶ Eu3+samples are one-dimensional nanorods with a diameter of 20 nm and a length of 300~500 nm. The coating thickness of SiO2 can be controlled by the concentration of TEOS. The results of photoluminescence properties show that the main emission peak of LaPO4 ∶ Eu3+ nanorods is near 591 nm, which is the characteristic orange red light corresponding to 5D0→7F1 transition of Eu3+ under 259 nm excitation. The PL intensity of the samples become weak with the increasing of the coating thickness, but the shape and the position of the peaks are not changed.关键词：LaPO4 ∶ Eu3+;nanorods;core-shell;coating;luminescence materials99|33|1更新时间：2020-08-12
- 摘要：TiO2/p+-Si heterostructures were formed by thermal oxidation of the sputtered Ti films on heavily boron-doped silicon (p+-Si) substrates. In order to make the TiO2/p+-Si heterostructures more suitable for electroluminescence, the TiO2 films should be anastate in crystal structure. This required the precursor Ti films possess small crystal grains. Such Ti films could be sputtered at relatively low sputtering power. Moreover, the thickness of TiO2 films should be controlled in a desirable range. The related mechanisms for the above-mentioned results have been discussed.关键词：TiO2;Si;heterostructure;electroluminescence111|83|1更新时间：2020-08-12
- 摘要：Uniform silica nanoparticles were synthesized via Stöber method, and fluorescent europium complex with three chelate ligands (i.e. dibenzoylmethane, phenanthroline and acrylic acid) has been prepared. The hydrosoluble silica nanoparticles adsorbed liposoluble europium chelate with strong fluorescence in the aid of ultrasonication and phase-transfer solvent, and then were coated by cationic polyelectrolyte polydi-allyldimethylammonium chloride and anionic polyelectrolyte poly(acrylic acid) (PAA) one layer by one layer. The obtained fluorescent nanoparticles were charactered by transmission electron microscopy, ultraviolet spectrophotometer, infrared spectrophotometer, fluorescence spectrophotometer and Zeta potential. These nanoparticles have the advantages of uniform size, strong fluorescence, good photostability and leakage free. Futhermore, the nanoparticles with rich carboxy groups resulting from PAA coated on their surfaces made the surface modification and bioconjugation easier. These properties suggest their great potential in the application field of biology and medicine.关键词：fluorescence;europium chelate;silica nanoparticles;polyelectrolyte155|88|1更新时间：2020-08-12
- 摘要：ZnMgO films were grown on the Al2O3 (sapphire) and ZnO substrates by metal-organic chemical vapor deposition (MOCVD) under different pressures. By analyzing the crystal structure, surface properties,optical and electrical properties of ZnMgO films, We found that different substrates and pressures have an important influence on growth and properties of ZnMgO films.Both high pressure of 5 kPa and ZnO substrate are better for Mg doping in ZnMgO.关键词：ZnMgO films;substrate;pressure94|160|0更新时间：2020-08-12
- 摘要：Taking account of the coupling differential equations under the effect of Stokes and anti-Stokes for the pump wave linearly polarized and aligned with the x-axis direction, the gain coefficient for the Stokes and anti-Stokes have been derived from simultaneously act of stimulated Raman scattering and parametric amplification in the same x polarization. The Lorenz model of parallel gain coefficient is introduced in this equation. The correlation between the gain spectrum and correlative parameter studied in dispersion-shifted fiber. The conclusion shows that gain spectrum is dissymmetrical with the Stokes and anti-Stokes wave and has no relation with third-order dispersion. At the same time, the ratio of Stokes and anti-Stokes |Eax/Esx| increases with frequency shift, then it rapidly reduced.关键词：dispersion shifted fiber;stimulated raman scattering;parametric amplification;gain coefficient;frequency shift115|148|1更新时间：2020-08-12
- 摘要：A method of the lossless identification for fiber cable based on white-light interference is studied. When the two ends of fiber-optic are connected, the light-wave is coupled into two beams of light with the same light intensity and transmit in the opposite directions. Detector receives signals generated by the other side. The two optical fibers side by side with the force of outside and the optical fiber path changes are analyzed. The output signals on some conditions are simulated and verified by experiment. The impact signal, the sinusoidal signal with a known frequency and the music signals are used as the divided external signal source, and the output signal is observed. By analyzing the spectral, and comparing with the input signal, this method of the lossless identification system is proved feasible.关键词：cable identification;fiber;white-light interference;lossless;voice recognition118|160|5更新时间：2020-08-12
- 摘要：The ternary complexe of europium with citric acid and 1,10-phenanthroline (Eu(Cit)Phen) with hydroxyl group and prepolymer of polyurethane(PU) with isocyanate groups-terminated were synthesized. Under the chain extension action of 1,3-propylene glycol, covalently bonded PU/complexes rare earth mate- rials were prepared by the ternary complexes and PU prepolymer via additive reaction of hydroxyl and isocyanate groups. Fluorescent nanofibers derived from the PU/complexes materials were prepared via electrospinning method. The nanofibers were characterized with Fourier transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimeters (DSC), and photoluminescence (PL). The results indicated that the diameters of the nanofibers were 300~800 nm; the ternary complexes were linked to polyurethane via covalent bonds, with the increased content of the ternary complexes, the diameters and crystallinity of the nanofibers decreased, the glass transition temperature and fluorescent intensity of the nanofibers increased gradually.关键词：rare earth complex;PU;electrospinning;nanofibers;photoluminescence102|189|1更新时间：2020-08-12
- 摘要：Three water soluble 1,8-naphthaline fluorescent monomers were synthesized by using 4-bromo-1,8-naphthalic anhydride and N-methyl-piperazine. The structures were characterized by IR, MS, 1H NMR and element analysis. The fluorescent excitation and emission spectra were investigated. The structures of the three flourescent monomers were optimized in the ground and the first excited state by PM3 method. The analysis of structure indicates that the rings in the three fluorescent monomers are in the same plane, and the conjugate system is formed. For all the optimal configurations, there is no imaginary frequency after vibrational analysis, which indicates that the structures are true local minima. On the basis of optimized structures for both the ground state and the first excited state, the time dependent density function theory(TD-DFT)at the B3LYP/6-31G* level was used to predict the absorption and emission wavelength.The results indicate that the wavelength of the excitation and emission spectra are well consistent with the experimental data.关键词：fluorescent monomer;density functional theory;excitation wavelength;emission wavelength;quantum chemistry139|295|4更新时间：2020-08-12
- 摘要：[Zn(BDC)(H2O)]n metal-organic framework films have been synthesized on the surface of zinc substrate by a hydrothermal reaction between zinc slice and 1,4-benzenedicarboxylic acid (H2BDC) at 140 ℃ for different reaction times. The films were characterized and analyzed with X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the films were constructed from nano- or microcrystals of [Zn(BDC)(H2O)2]n, a one-dimensional zig-zag type MOF. With increasing the hydrothermal reaction time, the particle sizes reduced gradually and then the nanoscaled crystals of [Zn(BDC)-(H2O)2]n films were obtained after 12 h. The formation mechanism of the films on the zinc substrate was preliminarily discussed. All samples of the films exhibited strong solid state fluorescence at room temperature with an emission maximum at 395 nm under excitation of 332 nm. Strong fluorescence quenching of the films was observed due to energy transfer between nitrobenzene quenchers and the MOFs chains through the electrostatic interaction. Fluorescence quenching efficiency increased linearly with the concentration of nitrobenzene in 0.25‰~2%, which indicate this film has a high efficiency, fast response,and reversible for nitrobenzene.关键词：metal-organic frameworks;in-situ preparation;thin films;fluorescence quenching;sensor119|39|1更新时间：2020-08-12
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