最新刊期
卷 34 ， 期 9 ， 2013
- 摘要：Two bifunctional mesoporous magnetic/luminescent nanocomposites were fabricated. Magnetic (Fe3O4) cores encapsulated in the mesoporous silica nanospheres and the terbium and erbium complex covalently bonded to the framework of mesoporous silica through the chelate ligand N-(4-benzoic acid-yl),N'-(propyltriethoxysilyl) (PABA-Si) and 5-[N,N-bis-3-(triethoxysilyl)propyl]ureyl-1,10-phenanthroline (phen-Si), respectively. The structure, magnetism, and photoluminescence properties of the obtained bifunctional nanocomposites were investigated. The results reveal that the nanospheres possess mesostructures, superparamagnetic behavior, and characteristic luminescence properties of the corresponding lanthanide complexes.关键词：bifunctional;mesoporous;superparamagnetic behavior;lanthanide complex;luminescence111|102|0更新时间：2020-08-12
- 摘要：By utilizing the oxidation property of hypochlorite (ClO-) and different coordinating properties of Cu+ and Cu2+, a high efficiency ClO- probe compound that based on Cu2+ chemosensor (CS1) was synthesized. The sensing properties of CS1 for ClO- was investigated by UV-Vis and fluorescene spectroscopy. The results showed the spectra of CS1 in the presence of Cu+ was highly affected by ClO-: (1) the maximum absorption peak shifted from 396 nm to 545 nm (Δλ=149 nm); (2) the fluorescence intensity at 520 nm decreased about 25 times. CS1 mimicked an AND logic gate function with Cu+ and ClO- as inputs and A470/A396 as output (A=absorbance), and this function could be easily reset by ethylenediaminetetraacetic acid disodium salt (EDTA).关键词：Cu+;hypochlorite;probe;logic gate94|118|0更新时间：2020-08-12
- 摘要：Red-emitting phosphors Ca4LaNb(W1-xMox)4O20:Eu3+ were synthesized by the solid-state reaction, and the photoluminescence properties of these compounds were investigated. The excitation spectra of Ca4LaNbW4O20:Eu3+ show a broad excitation band centered at 275 nm, which attribute to the charge transfer (CT) transition of WO42- complex. With the introduction of Mo6+ ions into Ca4LaNbW4O20:Eu3+, the absorption band at 275 nm broadens due to the enhancement of CT transitions of O2--Eu3+. The emission spectra of Ca4LaNb(W1-xMox)4O20:Eu3+ exhibit sharp emission peaks at 591 and 616 nm of Eu3+ transitions and a 400~500 nm broad emission band of WO42- transition. With the increase of Mo6+ content, the intensity of broad emission band of WO42- transition decreases. The pure red color is obtained.关键词：Ca4LaNb(W1-xMox)4O20：Eu3+;red-emitting phosphor;photoluminescence115|101|1更新时间：2020-08-12
- 摘要：The spiropyran has two tautomers, the ring-closed spiropyran form (SP) and the ring-opened merocyanine form (ME). In order to get more applications, the fluorescence of spiropyran needs to be enhanced. To produce a fused bifunctional molecule with full conjugated configuration and conformation, we synthesized a fused molecule with both functional groups of spiropyran and fluorescein. There exist many kinds of configuration and conformation in these molecules, but only the conjugated one makes sense. Femtosecond transient absorption ultrafast spectroscopy is used to characterize this fused molecule. The experiments demonstrate that there is a part of fully conjugated configuration and conformation, which can enhance the fluorescence intensity.关键词：photochromic;spiropyran;ultrafast spectroscopy156|128|0更新时间：2020-08-12
- 摘要：Different contents of molybdenum-doped ZnO were prepared by hydrothermal method, using Zn(NO3)2·6H2O and NaOH as precursors, CTAB, SDS, PVP-K30, PEG400, EDTA as additive. SEM images show that various morphologies of molybdenum doped ZnO can be obtained by changing the types of additives. XRD results indicate that the doped ZnO were wurtzite structure. With the increasing of the molybdenum concentration, the diffraction peak intensity are significantly enhanced and the crystalline quality is improved. There are violet emission peak at 385 nm and green emitting at 572 nm in the PL spectra of ZnO:Mo. The luminous intensity varies with the molybdenum concentration.关键词：molybdenum doped;hydrothermal method;photoluminescence123|203|4更新时间：2020-08-12
- 摘要：The bound polaron in a GaN/Ga1-xAlxN spherical finite-potential quantum dot under hydrostatic pressure is investigated by using a triangular potential to approximate the band bending of the interface potential. We performed numerical calculation on the binding energy of the electron-phonon and ion-phonon interactions. The binding energy of a bound polaron is compared with the case of square potential. The results show that the binding energy of bound polaron decreases with the increasing of electron areal density. We observed that the binding energy closes to the different values of electron areal density ns=(6.0, 8.0)×1011/cm2 when the dot radius R>10 nm. The ion-phonon interactions play a major role in the polaronic effect.关键词：quantum dot;the bound polaron;electron areal density88|58|0更新时间：2020-08-12
- 摘要：Calculation and detailed analysis were carried out to investigate the lattice parameter and defect formation energy of perfect zinc blend ZnTe, that with impurity Cu(Zn0.875Cu0.125Te) and that with Zn vacancies (Zn0.875Te) using the plane-wave ultrasoft pseudopotential method based on density function theory and generalized gradient approximation. We obtained the band structure, density of states,Mulliken populations, dielectric function, absorption spectrum, refractive index, reflectivity, optical conductivity and loss function of the three systems. The results show that Zn vacancy and Cu impurity have certain influence on the lattice parameters, energy band structure and optical properties. The volumes of defect systems decrease and the lattice parameters are changed to some extent compared to perfect ZnTe. The band gap decreases, providing a n-type conductivity to the top of the valence band of the acceptor levels due to the vacancy and introduction of impurity level. Moreover, the optical properties of ZnTe are improved as the absorption spectra show a remarkable redshift and the electron transition of the defect systems in the visible region are enhanced apparently accompanied with appearance of dielectric peaks.关键词：ZnTe;first-principles;electronic structure;optical property93|277|2更新时间：2020-08-12
- 摘要：A new 4-aminoantipyrine-based Schiff-base (M) was synthesized. Its structure was characterized by using IR, 1H NMR and elemental analysis. The influences of a number of different metal ions on its UV-Vis absorption and fluorescence spectral were studied in acetonitrile. Spectroscopic studies revealed that compound M could detect Cu2+ by UV-Vis absorption and fluorescence spectrophotometry. The stoichiometry ratio of M-Cu2+ was 1:1, respectively. Moreover, the detection limit was calculated to be 1.41 μmol/L for Cu2+ ion. The analysis suggested that M could beh ave as a fluorescent sensor for the selective detection of Cu2+ and the binding constant was 6.5×104 L/mol. Thus a new kind of chemosensor for Cu2+ with high sensitivity and selectivity was introduced.关键词：Schiff-base;aminoantipyrine derivatives;Cu2+;fluorescent probe104|56|1更新时间：2020-08-12
- 摘要：High-quality MgxZn1-xO semiconductor materials had been grown using plasma-assisted molecular beam epitaxy (P-MBE) on c-plane sapphire substrate by inserting special metal buffer layers. X-ray diffraction results show that the MgZnO films keep hexagonal structure when the mole fraction of Mg varies from 0 to 32.7%, and the full width at half maximum (FWHM) of the films are 0.08°~0.12°. To the best of our knowledge, the crystal quality should be one of the highest level ever reported. With the increasing of Mg content in the films, the room-temperature photoluminescence (PL) of ultraviolet emission peaks are shifted from 378 nm to 303 nm. A detailed study on Mg0.108Zn0.892O film by temperature-dependent photoluminescence shows that the bound exciton emitting has two different quenching processes with the temperature increasing. In addition, resonance Raman spectroscopy indicates that there is a linear relationship between the content of Mg in the films and the A1(LO) phonon mode frequency shift. This relationship provides a simple and efficient method to determine Mg content in MgxZn1-xO films. It is found that Raman spectroscopy is more sensitive to the component phase change than the X-ray diffraction characterization. Finally, the temperature-dependent Raman spectroscopy was employed for Mg0.057Zn0.943O and a theoretical explanation of A1 (LO) and A1 (2LO) phonon mode frequency shift with temperature was given and discussed.关键词：MgxZn1-xO;P-MBE;X-ray diffraction;photoluminescence;resonance Raman spectroscopy124|90|0更新时间：2020-08-12
- 摘要：Hollow semi-sphere SrWO4 and rare earth ions (Tb3+, Eu3+) doped SrWO4 microspheres were synthesized by hydrothermal treatment and characterized by XRD, SEM and photoluminescence (PL) spectrum. The results indicate that the undoped SrWO4 has hollow semi-sphere morphology, with a tetragonal phase structure. The phase structure of SrWO4 doped with Tb3+ or Eu3+ is similar to that of the undoped SrWO4, while the morphology transforms from hollow semi-sphere to microsphere. With the increasing of Tb3+ doping concentration, the morphology of SrWO4:Tb3+ changes from microsphere to micro-flower composed of many nanorods. The increasing of Eu3+ doping concentration leads to the presence of monoclinic phase Eu2WO6 and the morphology change of SrWO4:Eu3+. Under the excitation of UV light, the emission spectra of SrWO4:Tb3+ and SrWO4:Eu3+ are mainly attributed to the characteristic emission of Tb3+ (5D4-7FJ transitions, J=6, 5, 4, 3) and Eu3+ (5D0-7FJ transitions, J=1, 2, 3, 4), respectively. The optimal doping mole fractions are 3% for Tb3+ and 25% for Eu3+ in SrWO4.关键词：SrWO4;sphere;rare earth ions;luminescence92|74|0更新时间：2020-08-12
- 摘要：The apatite phosphors of Sr5-x(PO4)2SiO4:xEu2+ were prepared by a high temperature solid-state reaction method in a reducing atmosphere. The crystal structure, excitation and emission spectra and morphology of the samples were characterized by XRD, PL and SEM methods, respectively. The effect of Eu2+ doping concentration on the luminescence properties of Sr5-x(PO4)2SiO4:xEu2+ was also investigated. Two different luminescence centers were formed because Eu2+occupied two different crystallographic site in the crystal structure. Two emission bands located in blue and yellow light region were observed in a low concentration of Eu2+. Along with the increase of Eu2+ doping concentration, the PL intensity of emission peak in yellow light region gradually increased because of the energy transfer between Eu2+ ions, and reached the maximum value when x=0.075. Red shift of the emission peak may be due to the joint action of crystal field strength and the mechanism of energy transfer. The application of these phosphors to the white LED was also explored. It is found that the phosphors with double emission peaks are beneficial to the improvement of color rendering properties to the LED light sources.关键词：phosphors;apatite;two emission bands;white LED123|41|1更新时间：2020-08-12
- 摘要：ZnO:Mn thin films with different Mn concentration were prepared on glass substrates at room temperature using RF magnetron sputtering method. Raman spectroscopy, X-ray diffraction spectra and SEM were used to analyze the structural characteristics of the ZnO:Mn films. The results show that ZnO:Mn thin films have significant wurtzite structure with Mn doping mole fraction from 0 up to 5.6%. The redshift of Raman peaks at 437 cm-1 and 527 cm-1 can be explained by the lattice defects and disorder induced by the increasing of Mn concentration. The appearance of Raman spectra at 647 cm-1 indicates the formation of MnO, leading to the worse crystallization of ZnO:Mn films, which is also evidenced by XRD and SEM results.关键词：ZnO;Mn;Raman;diluted magnetic semiconductors83|196|0更新时间：2020-08-12
- 摘要：Tb3+ and Yb3+ codoped BaGd2ZnO5 phosphors were synthesized by high temperature solid-state method. Structures of the samples were investigated by X-ray diffraction. The excitation spectra and emission spectra were measured. With the increase of Yb3+ concentration, the visiable emission intensity decreases but the near-infrared emission increases. So the cooperative energy transfer from Tb3+ to Yb3+ is demonstrated. The luminesence lifetime decay curves of Tb3+ (544 nm) with different Yb3+ concentrations were measured. The dependence of lifetime, energy transfer efficiency and quantum efficiency on Yb3+ concentration were obtained. The highest quantum efficiency is 125.5%. The emission of Yb3+ 2F5/2→2F7/2(977 nm) is just above the band gap of crystalline sillicon, so this material can be applied in the sillicon-based solar cells to progress the conversion efficiency.关键词：cooperative energy transfer;near-infrared quantum cutting;lifetime;quantum efficiency131|138|0更新时间：2020-08-12
- 摘要：Tetragonal phase SrWO4 and SrWO4:Eu3+ nanocrystals were synthesized by a CTAB-assisted hydrothermal method. The nanocrystals were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM). The crystalline size of SrWO4:Eu3+ decreases with the increasing of Eu3+ and CTAB content in the reaction solutions gradually. Under 393 nm excitation, the 5D0→7FJ=1, 2, 3, 4) and 5D1→7F0 transitions are observed, and the luminescence is dominated by 5D0→7F2 transition, indicating that Eu3+ occupies a site lacking inversion symmetry. The positions of emission peaks are independent of excitation wavelength. When the excitation is performed at 466 nm, the emission intensity is the strongest.关键词：SrWO4：Eu3+;nanocrystals;photoluminescence94|66|4更新时间：2020-08-12
- 摘要：Yb3+, Ho3+ ions co-doped CdWO4 nano-crystals were synthesized by hydrothermal method. The characterization and structure of the samples were measured by X-ray powder diffractions (XRD),field emission scanning electron microscope (ESEM) and fluorescence spectrophotometer. The results show that CdWO4:Yb3+, Ho3+ is monoclinic crystal system with the mean size of 29.782 7 nm. The emission spectra were obtained when the samples were excited by 980 nm semi-conductor laser. The green (552 nm) and red (659 nm) emission peaks are obviously observed, which are corresponding to the 5F45S2→5I8 and 5F5→5I8 transitions of Ho3+ ions. According to the relationship between pump power and luminescence intensity, the green and red peaks can be due to the double-photons absorption processes. The concentration of the rare earths could influence the luminescence intensity. The strongest peak was obtained when the mole fraction of Ho3+ is 1.5% and the ratio of n(Yb3+):n(Ho3+)=5:1.关键词：CdWO4：Yb3+;Ho3+;up-conversion luminescence;hydrothermal method87|87|1更新时间：2020-08-12
- 摘要：The polarization control of vertical-cavity surface-emitting lasers with high power emission is demonstrated by using metal-grating to import non-isotropic gain. The grating with a period of 186 nm and a duty ratio of 0.5 was fabricated on the GaAs-cap layer to provide additional reflectance for TE polarization. The pairs of p-DBRs were reduced and the GaAs-cap between grating stripes was etched to force the current to be injected linearly along grating stripes to realize the maximum non-isotropic gain. A polarization ratio of 4.8, an output power of 780 mW and high temperature performance were demonstrated for a 550 μm aperture device. Key words : vertical-cavity surface-emitting laser; metal-grating; polarization controlling CLC number: TN248.4 Document code: A关键词：vertical-cavity surface-emitting laser;metal-grating;polarization controlling102|147|0更新时间：2020-08-12
- 摘要：A novel high gain rare earth ions co-doped fluoride phosphate fiber core material was designed. The influence of different component on system performance was studied, which was the key factor to prepare an optical fiber material with good thermal stability and high transmittance and non-crystallization. This fiber material has a high absorption cross-section (2.075 pm2), high emission section (1.11 pm2), long fluorescence lifetime (7.30 ms), and high gain coefficient (74.099×103 pm3). These good parameters indicate that the designed material is suitable for preparing excellent optical fiber amplifier material with high gain and wide bandwidth.关键词：high gain;fluoride phosphate;erbium-ytterbium co-doped97|81|0更新时间：2020-08-12
- 摘要：p-type AlN crystals by C and Si codoping were grown on SiC substrates by the sublimation method. The structural, optical and electronic properties of the samples were investigated by XRD, XPS, PL and Hall-effect measurement. The XPS analysis, especially about binding energies of Si 2p and C 1s peaks, reveals that in AlN crystals, C replaces N as an accepter and Si replaces Al as a donor. In PL spectroscopy, two main emission peaks are observed. Combined the structure and composition of AlN and related theoretical results, the two peaks are attributed to the complexes of VN-CN and CN-SiAl, respectively.关键词：PL;doping;p-type conduction;semiconductor materials;AlN120|160|1更新时间：2020-08-12
- 摘要：A white LED sample was fabricated which can be used to characterize the resistance of n-GaN at the range of 20 to 170 ℃. The results reveal an exponential relation between resistance and temperature. This relation is utilized to detect junction temperature of LED chip by measuring the resistance of n-GaN in a working LED. The white LED working in different junction temperature was achieved by changing the temperature of its heat sink. Their colorimetric parameters are measured simultaneously. These results show that the peak wavelength, rendering index, color temperature and luminous flux of white LED have a linear relationship with junction temperature.关键词：light emitting diodes;junction temperature;resistance;spectrum;colorimetric parameters145|145|11更新时间：2020-08-12
- 摘要：With the continuous development of high power semiconductor lasers in the field of laser processing, semiconductor laser fiber coupling modules with high coupling efficiency have become more flexible for most applications. In order to further increase the output power and brightness of laser diodes, a 808 nm wavelength fiber coupling module with 12 single-emitter laser diodes has been designed using ZEMAX optical design software, each single-emitter laser diode has an output power of 10 W with a 200 μm wide emission aperture. The core diameter of output fiber is set as 150 μm with a numerical aperture of 0.22. Finally, the simulated result indicates that the module will have an output power of 116.2 W with a coupling efficiency of 96.8%.The result is a good guidance for the practical application,thus further expanded the application field of laser diode.关键词：diode laser;ZEMAX;high efficiency;high power;optical fiber coupling592|880|8更新时间：2020-08-12
- 摘要：The pn junction characteristics of AlGaInP DH-LED was analyzed by using Matlab simulation. The relationship of current density J and voltage V at certain temperature (300 K) was obtained. Under low voltage, the current density increases linearly with the voltage. When the voltage increases to a certain value, the current density increases in logarithmic pattern. When the voltage is too high, the current density does not increase with the voltage. With the increase of voltage, the Joule heat of the device, and affect the device characteristics, and finally shorten the LED life. Comprehensive consideration, the theory of optimal driving voltage range finally load at 2~2.33 V. The research results provide theoretical reference and guidance for the design of LED array integrated device.关键词：AlGaInP;current-voltage relationship;pn junction;degenerate semiconducor111|75|1更新时间：2020-08-12
- 摘要：Based on rate equations, effects of laser parameters, including the pumped power, the reflectance of output mirror, the initial transmittance and the length of Cr4+: YAG, and the length of Yb3+:YAG on the laser performance were analyzed theoretically. Then based on theoretical conclusions, we designed a LD-pumped and passively Q-switched Yb3+:YAG microchip laser with narrow pulse width, high peak power and large pulse energy. The pulse width was 199 ps, the peak power was 1.04 MW, and the pulse energy was 0.21 mJ.关键词：microchip laser;passively Q-switched;Yb3+：YAG;Cr4+：YAG;rate equations131|98|2更新时间：2020-08-12
- 摘要：The continuous-wave single-mode operation of edge-emitting diode laser based on dual-sided non-quarter-wave Bragg reflection waveguide (BRW) was demonstrated at room temperature. A low-index core was utilized in the laser. The ridge BRW lasers (BRLs) exhibited an ultra-narrow twin-beam output. Single longitudinal mode emission with a very small spectral linewidth of 0.052 nm was measured. The lasing spectra showed a periodic modulation in the envelope with a mode spacing of approximately 3.3 nm. When the injection current of the BRLs was beyond 300 mA, a large mode hopping of the emission wavelength was observed.关键词：Bragg reflection waveguide;diode laser;spectrum modulation136|215|2更新时间：2020-08-12
- 摘要：The photoelectric properties of the light-emitting diodes were analyzed with various In content by software simulation and numerical calculation method. The relationship between In content and power spectral density, carrier concentration of the quantum well, radiative rates, and luminous power were investigated. The results show that the electron leakage and band filling are the main reason for impacting photovoltaic performance. When In content is lower, the spectrua blue shift is relatively small with the current density increasing(<8 kA/cm2), but the electron leakage will happen when the current density increases to a certain value(>8 kA/cm2), and the out power will reduce. When In content is higher, the spectrua blue shift is relatively larger with the current density increasing, however, the output power is higher. Accordingly, in order to make the InGaN/GaN light emitting diodes obtain the maximum quantum efficiency and light emitting efficiency, the In content need to be selected according to the value of the current density(8 kA/cm2).关键词：In concentration;efficiency droop;numerical simulate;InGaN/GaN LED182|360|1更新时间：2020-08-12
- 摘要：Amorphous In-Ga-Zn-O thin film transistors (a-IGZO TFTs) have potentials to be used in pixel circuits of active matrix organic light emitting display (AMOLED). However, bias stress effect still involves a-IGZO TFTs, evidently influencing performance of the corresponding AMOLED pixel circuits. In this study, inverted-staggered a-IGZO TFT devices were fabricated and measured, following which the corresponding Spice model was created. In addition, the dependence of stress time on threshold voltage (Vth) shift was theoretically modeled. By using SPICE simulation tool, we studied the stability properties of a-IGZO TFT-OLED pixel circuits in the forms of 2T1C and 3T1C, which proves there exists somewhat compensation effect on the Vth shift in 3T1C pixel circuit. Finally, we discussed and analyzed the way to further improve stability of a-IGZO TFT-OLED pixel circuits.关键词：a-IGZO;AMOLED;TFT;pixel circuit150|261|0更新时间：2020-08-12
- 摘要：In order to improve the power conversion efficiency of the organic solar cell, a solution-processed vanadium pentoxide was used as an anode buffer layer. The solution-processed V2O5 nanowire was synthesised by using hydrothermal method. The device structure was ITO/TiO2/P3HT: PCBM/V2O5/Ag. The influence of V2O5 concentrations and annealing temperature on the device performance was investigated. The experimental results indicate that the power conversion efficiency (PCE of 2.35%) is the highest when the V2O5 mass concentration is 300 μg/mL, much higher than that without anode buffer (PCE of only 0.14%). Moreover, 80 ℃ is the relative optimum annealing temperature of V2O5. Compared with thermal evaporation method, the solution-processed approach is relatively simple, attractive for mass production and greatly valuable for applications.关键词：V2O5;solution-processed;solar cell;hydrothermal method104|88|0更新时间：2020-08-12
- 摘要：The tunable optical filter is widely used to tuned the waveband by adjusting interference cavity length. It needs to prepare high reflective suspended membrane. However, the moving of suspended membrane is restricted under the influence of the driving voltage. The narrow transmission peak and the large tuning range are hard to be satisfied at the same time. Therefore, one of the media in photonic crystal is replaced with superconductor material in this paper. Based on superconducting theory the transmission spectra of one-dimensional superconductor-medium Fibonacci photonic crystal are calculated by applying transfer matrix method. The effect factors on transmission spectra of parameter such as Fibonacci level, refractive index of medium layer, thicknesses of medium and superconductor layer, temperature are discussed. The results show that a serious of passing band appears at the forbidden band of superconductor because of the influence of photonic band gap. The first transmission peak becomes sharper with the increasing of Fibonacci level. The transmission spectra move towards the long wave direction when the optical thickness of medium layer increases, the thickness of superconductor layer decreases and temperature rises. At last, based on analysis of spectra, the filter property of structure expressed as is given. Besides, the tunable band of filter is determined on condition that the half-width and tunable range are both considered, and temperature-controlled tuning is achieved without adjusting any dimension parameters.关键词：Fibonacci photonic crystal;superconductivity;transfer matrix method;temperature-controlled tuning86|192|1更新时间：2020-08-12
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