最新刊期
卷 32 ， 期 9 ， 2011
- 摘要：A series of NaYF4:20%Yb3+, 1%Tm3+ upconversion particles (UCPs) with different morphology were prepared by the facile hydrothermal approach. The morphology, crystalline phase and optical properties were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and luminescent spectra. XRD patterns and SEM images showed that the UCPs crystalline phase tansformed from cubic phase to hexagonal phase by controlling the reactants concentration. Pumped with 980 nm diode laser, the UCPs emitted bright violet/blue upconversion luminescence. By analyzing the effect of reactants concentration on the products crystalline phase, the crystal growth mechanism of NaYF4 was studied in detail. Significantly, our research work would provide more experimental data for controlling the crystalline phase of the upconversion luminescent materials.关键词：NaYF4;rare earth;reactants concentration;crystalline phase;upconversion106|75|4更新时间：2020-08-12
- 摘要：Two kinds of novel molecular glasses based on self-assembly dendritic chromophores are designed and synthesized as second-order nonlinear optical (NLO) materials, which named ETO and ETF. The chromophore glasses ETO and ETF showed excellent film-forming ability by themselves. Their glass transition temperatures (Tg) were determined at 41 ℃ and 39 ℃, respectively. The in-situ second harmonic generation (SHG) measurement revealed the resonant second-order NLO coefficient (d33) values of 38 and 32 pm/V for the poled films of ETO and ETF, respectively. The results indicate molecular glasses provide a new possible way different from the conventional polymer approach to prepare second-order NLO materials.关键词：molecular glass;chromophores;NLO;anthracene115|133|0更新时间：2020-08-12
- 摘要：Owing to its poor water resistance, the application of SrAl2O4:Eu2+, Dy3+ phosphors is limited seriously. In this paper, a rapid combustion method was introduced into the surface treatment of SrAl2O4:Eu2+, Dy3+ phosphors. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, photoluminescence spectrophotometry and pH measurements were employed to characterize the treated and untreated phosphors. Experimental results showed that a compact layer was coated on the surface of SrAl2O4:Eu2+, Dy3+ phosphors, which effectively improved the water resistance of phosphors.关键词：long afterglow;SrAl2O4：Eu2+;Dy3+;combustion method;surface treatment119|78|4更新时间：2020-08-12
- 摘要：2,4,6-Tris(2-pyridyl)-1,3,5-triazine, p-hydroxybenzoic acid and p-phthalic acid have been reported as ligands by many researchers recently. And these ligands react with rare earth ions producing the corresponding complexes, which have excellent luminous performances and are expected to be good luminescent materials. In this paper, we firstly reported that the TPTZ ligand reacted with dysprosium ion, produced the corresponding complexes. These complexes were fully characterized with UV, IR and elementary analysis. The composition of these complexes were supposed to be: (1)Dy(TPTZ)(NO3)3(C2H5OH)·H2O; (2)Dy-(TPTZ)2(NO3)3 (C2H5OH)·H2O; (3)Dy2(TPTZ)(NO3)6(C2H5OH)·2H2O;(4)Dy(TPTZ)-(C7H5O3)3(C2H5OH)·2H2O;(5)Dy2(TPTZ)2 (C8H4O4)(NO3)4(C2H5OH)·H2O. The oxygen atoms of nitrate and carboxyl group from aromatic acids coordinate to dysprosium ion, nitrogen atoms from TPTZ generate bonds with dysprosium ion. The formation of complex has little effect on conjugation bond π-π* electron transition of the ligand. The luminous intensities of dysprosium complexes with different composition are different. The p-phthalic acid complex has the strongest fluorescence intensity. Fluorescence intensity of the complex (2) is stronger than complex (1), while fluorescence intensity of the complex (3) is stronger than complex (2). It shows that the more TPTZ ligands or dysprosium ions are, the stronger fluorescence intensity is. Fluorescence intensity of the complex (4) is stronger than complex (1).It shows that the p-hydroxybenzoic acid is better at absorption and transmission of light than nitrate. Fluorescence intensity of the complex (5) is the strongest in all the complexes. It shows that p-phthalicacid has the strongest absorption of light, it also shows that when Dy ions at higher concentrations, the fluorescence intensity is also stronger.105|172|0更新时间：2020-08-12
- 摘要：YxAl5O12:Ce3+ phosphors have been synthesized by co-precipitation method. The crystalline structure, morphology and luminescence properties of YxAl5O12:Ce3+ phosphors have been investigated by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and fluorescence spectrophotometer. The results show that the emission wavelengths of as-prepared phosphors display red-shift at first and then blue-shift appears with the molar of Y3+ increasing from 2.64 to 3.06. The emission intensity increases slowly with the mole of Y3+ increasing from 2.64 to 2.88, but the intensity decreases sharply with different Y3+ content when it was beyond 2.94. The maximum emission wavelength (λem=537 nm) at the maximum intensity appears when x is 2.88. The impure phase-Al2O3 appears when the content of Y3+ is below 2.64. When the mole of Y3+exceeds 3.06, the impure phase-YAM appears, which has negative effects on the luminescence property of as-prepared phosphors. When the molar ratio of yttrium rises from 2.76 to 2.88, the powder is observed with high crystalline and easy dispersion.关键词：YxAl5O12：Ce3+ phosphors;co-precipitation method;spectral red-shift90|101|1更新时间：2020-08-12
- 摘要：Ce3+-doped lutetium oxyorthosilicate (Ce: Lu2SiO5) films have been fabricated on silicon (111) substrates by Pechini sol-gel method combined with the spin-coating technique. Thermogravimetry-differential scanning calorimetry (TG-DSC) analysis, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), PL (Photoluminescent) measurements under VUV as well as spectroscopic ellipsometry (SE) were used to characterize the resulting films. The results indicate that the Ce: Lu2SiO5 films begin to crystallize at 900 ℃ and are completely crystallized at 1 100 ℃. The phosphor films are uniform, dense and crack-free. The VUV spectra show that the excitation is mainly host excited and the emission spectrum is a broad band centered at about 400 nm. The refractive index, the extinction of coefficient are 1.82~1.94 and 0.005~0.05, respectively, the thickness measured by spectroscopic ellipsometry is similar to that obtained by SEM.关键词：sol-gel method;Ce:LSO film;luminescence;VUV spectra;optical constants109|207|0更新时间：2020-08-12
- 摘要：YAlO3:Pr3+ is a good candidate for various luminescent applications. The crystal field parameters and energy levels of Pr3+ doped YAlO3 are studied via a least-square optimization of the calculated to the measured energies of the 4fN levels using the f-shell computer program. The optimization procedure requires the initial values of all the parameters appeared in the 4f 2 effective Hamiltonian. The initial values of the free ion parameters are taken from those of Pr3+ in LaF3, and those of the crystal field parameters are taken from those of Nd3+ in YAlO3. All the 4f 2 energy levels of Pr3+ are then calculated using the parameters obtained via the optimization procedure. Comparing the crystal field parameters of Pr3+ to those of Nd3+ and Er3+ in YAlO3, it is found that the majority of the modules of the crystal field parameters decreases with increasing nuclear charge of the rare-earth ions.关键词：Pr3+;YAlO3 crystal;crystal-field parameters;luminescence of rare-earth ions121|289|2更新时间：2020-08-12
- 摘要：A series of novel blue light emitting materials 9,9'-bianthracene derivatives have been designed and synthesized by introducing different substituent groups through Suzuki coupling reactions. Their structure was identified by 1H NMR and UV-Vis absorption and fluorescence emission. Moreover, their fluorescence quantum efficiency and electrochemical properties were characterized in detail. The results indicate that all these compounds emit blue light, compared with 9,9'-bianthracene, the maximum emission peak of these materials is at 453 nm, red shift of 7 nm, and it is the typical blue fluorescence. This is because these derivatives have a non planar geometric structure. These derivatives also present high fluorescence quantum efficiency and are 1.18~ 1.43 times than 9,9'-bianthracene. In addition, their redox actives are also improved. Consequently, it was believed that these derivatives are potential ideal blue light fluorescent materials.关键词：blue emitting materials;9;9'-bianthracene;synthesis;OLED101|155|4更新时间：2020-08-12
- 摘要：GaN is considered as a promising material for high power, high temperature and high frequency microwave applications, due to the wide band gap, high thermal stability and high breakdown voltage. Due to lack of suited homosubstrates, GaN is currently grown on heterosubstrates where SiC is the most popular choice for commercial applications. However, it is difficult to obtain high quality GaN because of the 33.1% mismatch of thermal expansion coefficients and the large lattice mismatch (3.5%) between GaN and SiC. In this paper, GaN epitaxial layers were grown on 6H-SiC substrates by metalorganic chemical vapor deposition. Samples employing high temperature AlN as buffer layers produce high quality GaN epitaxial layers. Five samples with different AlN buffer layers were prepared. The effects of the growth parameters of AlN buffer layers on characterizations of GaN were studied. The highest quality GaN layer grown on SiC substrate with AlN buffer was obtained by optimizing the growth parameters of the AlN buffer. The full width at half maximum of High-resolution X-ray diffraction on-axis (0002) and off-axis (101 2) diffraction are 130 arcsec and 252 arcsec, respectively. The values are the best result of GaN grown on homemade 6H-SiC. The quality of GaN layers will be deteriorated by increasing the thickness or the growth Ⅴ/Ⅲ ratio of AlN buffer layers, while the low growth temperature of AlN buffers also deteriorate the quality of GaN layers. The strain in GaN also has been studied. It is found that the GaN layer with narrow XRC FWHM has less stress intensity.关键词：GaN;AlN;SiC;MOCVD;XRD130|260|5更新时间：2020-08-12
- 摘要：Carbon cones were grown on silicon substrates by bias-enhanced chemical vapor deposition using methane, hydrogen and ammonia as the reaction gases, and the silicon substrates were pre-deposited with titanium and carbon films, respectively. The cones were characterized by scanning electron microscopy, energy dispersive X-ray and micro-Raman spectroscopy. The results indicate that the cones are CN structure. The photoluminescence of CN cones was investigated by micro-Raman spectroscopy at room temperature and the photoluminescence spectrum showed three emission bands centered at about 621,643,726 nm, respectively. According to the photoluminescence mechanism of CN films, the photoluminescence of CN cones was analyzed.关键词：CN cones;Raman spectrum;photoluminescence mechanism104|200|0更新时间：2020-08-12
- 摘要：Electronic structure and optical properties of Stressed Ru2Si3 have been calculated and compared using the first-principle density function theory pseudopotential method. The calculated results show that the energy band-gap increases with increasing the positive stress; the energy band-gap decreases with increasing the negative stress, and Ru2Si3 always is direct band-gap semiconductor. The curves of optical properties tend to high-energy direction with increasing the stress.关键词：Ru2Si3;first-principles;stress;electronic structure113|96|5更新时间：2020-08-12
- 摘要：Lu2O3:Eu3+ nano-powders were prepared by co-precipitation and solvo-thermal methods, respectively. The microstructural evolution of Lu2O3:Eu3+ phosphor powders obtained by above two methods were analyzed and compared by means of XRD, FTIR and SEM. The obtained powders without any additive were sintered into transparent ceramics under vacuum at 1 100 ℃ for 5 h and then in nitrogen atmosphere at 1 700 ℃ for 2 h and at 1 600 ℃ for 10 h. The excitation and emission spectra of Lu2O3:Eu3+ for the calcined powders and transparent ceramics were respectively measured at room temperature. Transparencies of the obtained transparent ceramics were compared. The fluorescence decay was measured and discussed under different excitation wavelengths for the prepared Lu2O3:Eu3+ transparent ceramics.关键词：Lu2O3：Eu3+;transparent ceramics;photoluminescence;fluorescence decay127|131|3更新时间：2020-08-12
- 摘要：The ZnO/Ag/ZnO multiple films with different thickness of Ag film were grown via magnetron sputtering method. The morphology, optical absorption spectra, photoluminescence and photoresponse properties were studied. The results exhibited that the intensity of photoluminescence was increased with the adding of the Ag film into ZnO film. The photo responsivity was 0.06 A/W at 350 nm when the thickness of the Ag film was 6 nm. Compared with ZnO film this value was improved one magnitude. However, the photo responsivity was decreased when the thickness of the Ag film was reached 15 nm.关键词：ZnO multiple film;Ag film;photoluminescence;photoresponse109|108|1更新时间：2020-08-12
- 摘要：Si1-xGex films were deposited by ion beam sputtering on SiO2 and monocrystalline Si substrates respectively. The Si1-xGex films were doped with phosphorus and boron respectively through thermal diffusion to form n- and p-type films. The Si1-xGex film is polycrystalline. And the Co/poly-Si1-xGex Schottky junctions were performed. The surface roughness and electrical properties were measured right after they were dealt with rapid thermal annealing (RTA) at different temperatures. With the increasing of annealing temperature, the surface roughness and the ideal factor characterizing the Schottky contact deviation from ideal status increase, while the Schottky barrier height (SBH) just changes slightly. The interfacial defect density increases with the annealing temperature increase,which is the main reason for the ideal factor going up. The Fermi level pinning effect originating from the interfacial state and Cobalt Germanium silicides formed by solid state reaction having almost the same work function with Cobalt itself are the two principal aspects responsible for nearly invariant SBH.关键词：rapid thermal annealing;Shottky junction;Shottky barrier height;electrical characteristics104|188|0更新时间：2020-08-12
- 摘要：A high efficiency organic light emitting device (OLED) was fabricated by a facile way based on an ultra thin praseodymium fluoride (PrF3) as the anode buffer layer. The PrF3 anode buffer layer device shows some dramatic properties such as higher hole injection, stable and high current efficiency, and much higher luminance compared with those of the traditional ITO anode device. The 0.5 nm PrF3 anode buffer layer device gives the maximum current efficiency and luminance of 4.9 cd/A and 33 600 cd/m2, respectively, comparing with the traditional ITO anode device of 3.7 cd/A and 12 320 cd/m2. The reason of the optimized device was also discussed.关键词：OLED;PrF3;anode buffer layer;work function119|99|2更新时间：2020-08-12
- 摘要：Micro-optical side-emitting light pipe can transform LED light from point source to linear source and it has the advantages of both LED and CCFL when used in LCD backlight module. In order to achieve good performance of light pipes with different lengths, this article, improves the light pipe model and introduces nonlinear correcting parameter α based on scattering netted dots formula, then the optimized dots arrangement of the light pipes with different lengths is presented. To solve the problem of low utilization efficiency in short light pipes, we radiate the light into one end of the pipe with the other end coated with reflective film, which significantly improves the light utilization efficiency. The results of simulation experiments show that the light utilization efficiency of the pipe can reach to 63% and the uniformity is up to 93%. This kind of light pipe can be used in LCD backlight module of large and medium sizes screen.关键词：light pipe;dots arrangement;utilization ratio;uniformity132|148|5更新时间：2020-08-12
- 摘要：Based on the principles of Gaussian beam collimation, collimation lens of different parameters were selected according to the laser beam characteristics of different high-power vertical cavity surface emitting lasers to study the different conditions of continuous and pulsed current excitation beam collimation. For a 200 μm aperture device, through the of f=3.1 mm, NA=0.68 lens, under continuous work conditon,the minimum of collimated divergence angle is 1°, under the current 40 A, pulse width 60 ns, the pulse repetition rate of 1 kHz condition, the minimum collimated divergence angle is about 2°. Results also show that under the same NA conditions, the collimated divergence angle linerly decreases when focal length increases.156|278|2更新时间：2020-08-12
- 摘要：A photonic approach for microwave frequency measurement is proposed. A phase difference of the two microwave signals carried on two optical wavelengths is induced by a tunable dispersion medium. The interference microwave power is tuned periodically by changing dispersion value. The frequency of the microwave signal can be extracted from the period. In the proposed approach, a 7-bit optic delay line composed by 8 magneto-optical switches and 1.6 km single-mode fiber (SMF) is utilized as the tunable dispersion medium. The measurement accuracy remains within ±40 MHz over a range of 1~20 GHz. The minimum measureable power can reach to -20 dBm and the dynamic range is 45 dB.关键词：microwave frequency measurement;photonic;optic delay line;dynamic range123|477|1更新时间：2020-08-12
- 摘要：Based on the study of microcavity-taper coupling system, the impacts of the coupling distance from the exterior vibration noise is introduced, and the relation between the coupling distance and the coupling state is analyzed systematically. To further validate the stability of the system and to avoid the disruption from the exterior vibration noise, two methods are taken to suppress the effect specially. One is to cover the coupling system with a designed isolation mantle. The other one is to package the tapered fiber with the microcavity into an entire body by using the UV mucus. The experimental results show that both the two methods are feasible and can make the system stable. Especially in the second scheme, the integrated microsphere-taper system is completely isolated from the outside, and it will not be interfered by the exterior vibration noise. This structure paves the way for the follow-up experiment.126|160|5更新时间：2020-08-12
- 摘要：Un-doped and Cu-doped ZnO thin films were grown on c-Al2O3 substrate by metalorganic chemical vapor deposition (MOCVD) system. The way of changing the temperature of Cu(tmhd)2 source bottle was used to change the saturated vapor pressure of Cu (tmhd)2, in the meantime to change the quantity of Cu(tmhd)2 carried into the the reaction chamber. Then the content of Cu in ZnO films was tested to study the effects of Cu doping on the luminescent properties of ZnO, and explore the process technique and condition of controlling Cu valence in ZnO films. X-ray diffraction (XRD) show un-doped ZnO and ZnO:Cu samples have good c-axis preferred orientation growth. The Cu content of these samples were measured by X-ray photoelectron spectroscopy (XPS). The content of Cu in ZnO films were not increased when the Cu(tmhd)2 source temperature was increased, which indicated that increasing the Cu(tmhd)2 source temperature did not lead to any increase of the Cu-doping level, and the solubility of Cu ions in ZnO is quite low. Low-temperature photoluminescence (PL) measurements show a strong and broad blue-violet (BV) light emission peak ranging from 2.8 to 3.3 eV, which could be assigned to donor-acceptor pair (DAP) recombination (between unknown shallow donor level and Cu-related acceptor level). Temperature dependent PL show a red-shift of the BV emission with increasing the temperature from 10 to 180 K, and a new weak shoulder peak appearing at BV emission's high-energy side at 80 K, which could be assigned to eA0. Moreover, the decrease of Cu content in ZnO:Cu film resulted in quenching the intensity of BV emission red-shift of BV emission's peak position. This phenomenon is interesting and rarely reported in the previous works. However, we still need further study to clarify that if it is the electron transition between Zni-related donor energy level and valence band that causes the BV emission.关键词：Cu doped ZnO;MOCVD;BV emission;photoluminescence101|133|1更新时间：2020-08-12
- 摘要：By combining 7-diethylamino-2-oxo-2H-chromene-3-carbohydrazide with 2,4-dinitrophenylhydrazine into one molecule, fluorescent probe (DC) was synthesized for dsetection of H2PO4- in acetonitrile. Spectrophotometric titration indicated the formation of a 1:1 complex of H2PO4- with DC. With the fluorescence spectra, the apparent red shift of UV absorption and the changes for the solution color from orange yellow to purple were observed as binding DC with H2PO4-. The experiment showed that DC was highly selective for H2PO4-, much more than those anions such as F-,NO3-,Cl-,Br- and I-. By the exclusive selectivity of DC to H2PO4-, it was predicted that as a fluorescent probe, and by means of fluorescence and UV-Visible absorption spectrum, H2PO4-can be rapidly identified by a enhanced fluorescence from DC.关键词：fluorescent probe;H2PO4-;photoluminescence109|228|1更新时间：2020-08-12
- 摘要：In this study, three dimension fluorescence spectra of standard sample of Advanced Glycation End products (AGEs), and skin self-fluorescence of AGEs are analyzed. The optimal excitation wavelength for skin AGEs is 370 nm. The skin self-fluorescence of control subjects and diabetic patients are measured by an instrumentation developed by ourselves. The results show that there are three obvious emission peaks at 418, 450, 470 nm, after normalizing the fluorescence spectra. It's distinctly that the peaks around 450 nm and 470 nm are correlated with the concentration of skin AGEs. Therefore, skin self-fluorescence excited by 370 nm can be utilized to quantitatively analyze the concentration of AGEs, and are also available for clinical diagnosing of correlated diseases.关键词：advanced glycation end product;fluorescence spectra;tissue optics;non-invasive measurement145|370|2更新时间：2020-08-12
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