最新刊期
卷 39 ， 期 8 ， 2018
- 摘要：A series of CaGd2-x-y(MoO4)4:xEu3+,yBi3+(x=0.01-2, y=0-0.04) red phosphors were synthesized by a hydrothermal method. The crystal structure, microstructure and luminescent properties of the samples were studied by the use of XRD, SEM and FL spectrophotometer, respectively. The results reveal that the powders with the doping mole frsction of 15% Eu3+ and 1% Bi3+ hold the structure of body-centered quartet scheelite which belongs to the space groups of I41/a(88). The particles of the sample are relatively uniform and the grain size is 3 to 5 μm. The excitation spectra of the samples are made up of a wide excitation band between 200-350 nm and excitation peaks between 350-500 nm. The strongest excitation peak locates at 396 nm, which indicates the sample can be effectively excited by near-UV light. The strongest emission peak locates at 617 nm corresponding to the 5D0→7F2 transition of Eu3+. The concentration quenching phenomenon of Eu3+ is not found in the present study. The dope of Bi3+ can sensitize Eu3+ to significantly improve the red emission intensity and the color purity of the sample. The best doping mole fraction of Bi3+ is 1%.关键词：hydrothermal method;white LEDs;near-UV;CaGd2(MoO4)4:Eu3+;Bi3+;red phosphors119|481|1更新时间：2020-08-12
- 摘要：YAG:Ce,Yb nano-phosphor with different doping concentrations was synthesized under various sinter temperature via sol-gel method. The morphology and structure of the resulting products were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The luminescence properties of the phosphors were studied by photoluminescence spectra and lifetimes. The samples show a rise in particle size with increased calcination temperature. Under 1 000℃, pure YAG phase with an average particle size of~84 nm are obtained. The quenching concentration of Yb3+ in the aforementioned phosphors exhibits a decrease from 10% to 5%, probably due to more homogeneous distribution of doping ions in the system of sol-gel products.关键词：YAG:Ce;Yb;sol-gel method;nano-phosphor;quenching concentration125|151|3更新时间：2020-08-12
- 摘要：Uniformed NaYF4:Yb3+,Tm3+ nanoparticles were synthesized through solvent thermal method in chloride. PAA-based ligand replace strategies were carried out to introduce free carboxylic acid groups which allowed further conjugation with NH2-containing human IgG. The silicon wafer was modified with rabbit anti-goat IgG by using protein G as "bridge", which contributed to eliminate structural or conformational changes of IgG. Owing to the specific antibody recognition to the antigenic, a simple, rapid, efficient and sensitive immunoassay method was developed. The experimental results demonstrate that there is a very good linear correlation between the upconversion luminescence intensity and the amount of goat anti-human IgG in the range of 5~400 nmol/L. The detection limit is as low as 1.82 nmol/L. Our developed detection system shows excellent detection specificity and sensitivity, which provides a new detection method and platform with wide linear range and high sensitivity for diagnosis of major clinical diseases in the future.关键词：upconversion;sandwich immunoassay;biosensor;specificity124|194|1更新时间：2020-08-12
- 摘要：LaCoO3 and La0.75Ca0.25Co0.5Fe0.5O3 materials were prepared by solid-state method, which were characterized by using the detection methods, such as XRD, SEM, XPS and IR. The electronic structures and optical properties of the samples were calculated by using the computer simulation software CASTEP. Based on the above results, the infrared radiation properties of the studied materials were investigated, further the improving mechanism of infrared emissive properties was analyzed. The results show that the crystal structure is changed from the rhombohedral structure for the non-doped sample to the cubic structure for Ca-Fe co-doped sample, and the emissivity in the 2.5-5 μm range was increased from 0.83 for the non-doped sample to 0.9 for Ca-Fe co-doped sample. The increasing mechanism of the emissivity is considered as the following aspects:Fe3+↔ Fe4+ and Co2+↔Co3+ mini-polarons form, which enhance the free carrier absorption. The defect levels appear at the Fermi level by the 3d orbital hybridization of Co atom and Fe atom, which promote the transition of excited electrons. Ca-Fe co-doping undermines the lattice symmetry in a certain degree, promoting the lattice vibration absorption and improving the infrared emissivity of the material. The lanthanum cobalt oxide system material has excellent emission performance in the mid-infrared band and can be applied in the high-temperature furnace industry.关键词：perovskite;lanthanum doping;infrared emissivity;optical properties;ceramic materials109|487|2更新时间：2020-08-12
- 摘要：Nitrogen doped carbon quantum dots(N-CQDs) were prepared by microwave reaction method with citric acid and glutamic acid as raw materials, polyethylene glycol(PEG) as dispersant. The transmission electron microscopy, ultraviolet visible absorption spectroscopy, fluorescence spectroscopy and infrared spectroscopy were used to research the influences of different preparation factors on the structure and property of N-CQDs. The optimum conditions are shown as follow:80 mg/mL citric acid is blended with 16 mg/mL glutamate and 80 mg/mL PEG then microwaved for 3.5 min at 800 W power condition. The N-CQDs prepared in the optimum conditions are size homogeneous, dispersity well and pH sensitive. Meanwhile, they possess excitation wavelength dependence, the maximal excitation wavelength is 340 nm, and the emission peak moves to 430 nm. Moreover, the study of infrared spectroscopy shows that hydroxy, carbonyl and other functional group abound in the surface of N-CQDs, it causes the great water solubility and biocompatibility. Thus, N-CQDs show a significant application potential in rapid detection of food industry.关键词：N-CQDs;microwave reaction method;optimal conditions;fluorescence intensity142|108|1更新时间：2020-08-12
- 摘要：β-NaYF4:20%Yb3+,2%Er3+ upconversion crystals co-doped with Cu2+ ion were prepared by a solvothermal method. X-ray diffraction(XRD) and transmission electron microscopy(TEM) analysis demonstrated that the phase and morphology of the samples did not change significantly with increasing Cu2+ ion doping concentration. The upconversion emission intensities in the UV/violet and visible regions increased at first and then decreased with the increase of the dopant concentrations of Cu2+ ion from 0 to 40%. The β-NaYF4:Yb3+,Er3+ microcrystals co-doped with 5% Cu2+ ion exhibited the maximum upconversion emission intensity. It may be attributed to the substitution of Y3+ ion by low-valence Cu2+ ion, which may generate F- vacancies. It decreased the crystal symmetry around the Er3+ ion, and favored the improvement of the upconversion luminescence.关键词：β-NaYF4;upconversion;Cu2+ion;doping111|70|1更新时间：2020-08-12
- 摘要：A series of phosphors α-Ba3Y(BO3)3:Dy3+ have been synthesized via conventional solid-state method and characterized. Fluorescence spectra (FL) show that the as-synthesized phosphors mainly exhibit two dominating emission peaks at 488 and 577 nm corresponding to the transitions from 4F9/2 to 6H15/2 and 6H13/2, respectively under ultraviolet (UV) or blue radiation. The best synthesis temperature is 1 100℃, leading to the most intensive luminescence, pure phase and most sufficient crystal growth ensured by FL, X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The concentration quenching mechanism has been determined to be mainly dipole-dipole interaction and exchange interaction is not negligible due to the specific unit cell structure; the critical concentration is 0.07. The second-order exponential lifetime decay curves are observed and its origin related to the specific unit cell structure is discussed. The as-synthesized phosphor has potential application for pc-WLEDs in the lighting field.关键词：phosphors;α-Ba3Y(BO3)3:Dy3+;crystal structure118|172|0更新时间：2020-08-12
- 摘要：Impurity-free vacancy diffusion (IFVD) induced quantum well intermixing (QWI) of red light diode laser wafer using GaAs encapsulation is explored. The wafer has an active region of a 9 nm-thick GaInP quantum well and two 350 nm-thick AlGaInP barriers. The GaAs dielectric layer is prepared through MOCVD. The QWI is induced by rapid thermal annealing at 950℃ at different times and different thicknesses of GaAs. Blue shifts and full width at half maximum (FWHM) are obtained through photoluminescence tests. A maximum blue shift of 53.4 nm is obtained at 120 s and an optimal FWHM of 18 nm by the IFVD-induced QWI is noted at 1 min.关键词：blue shift;impurity-free vacancy diffusion;quantum well intermixing;diffusion132|144|2更新时间：2020-08-12
- 摘要：In order to improve the absorption cross section and increase the photoluminescence efficiency of Tb3+ ions doped silica thin film, SnO2 nanocrystals with larger absorption cross sections were introduced into the silica thin films, and the greatly enhanced photoluminescence intensity was obtained because of resonant energy transfer mechanism. Firstly, Tb3+ and SnO2 nanocrystals codoped silica thin films were fabricated by use of sol-gel and spin coating methods according to the restrictive crystallization principle. The characteristic photoluminescence emission intensity of Tb3+ ions at 541 nm was enhanced by two orders of magnitude for the film sensitized by SnO2 nanocrystals with the optimized Sn4+ concentration. The photoluminescence excitation spectra indicate the non-radiative energy transfer process that takes place between Tb3+ ions and surface of SnO2 nanocrystals. Meanwhile, the photoluminescence intensity decay curves suggest the partial incorporation of Tb3+ ions into the SnO2 sites, which explains the greatly improving energy transfer efficiency. All these results indicate that SnO2 nanocrystals could be benefit for enhanced photoluminescence of Tb3+ ions doped silica thin film as a potential sensitizer.关键词：thin film;nanocrystal;rare-earth ion;sol-gel preparation;photoluminescence118|72|0更新时间：2020-08-12
- 摘要：A focus optical system was designed to focus the rectangular spot of 2 750 W direct laser diodes stack for laser material processing. First, the beam transformation principle was analyzed theoretically. The invert Kepler telescope system principle was applied to expand and collimate the laser beam in the slow axis direction. The fast and slow axis beams were synchronous focused by focus lens. The formula of focus spot size in the fast and slow axis directions was deduced, and the theoretical value of focal depth was calculated. The influence factors of the focus spot size were analyzed. Second, LD stack and the whole optical system were simulated by ZEMAX software. After the ray tracing, the beam variation form and simulate focus spot were obtained. Finally, the experiment was performed, a focus spot whose size was 1.5 mm×4.0 mm with 250 mm focal length, and 18.6 mm focal depth was obtained. The merit and demerit of the whole focus optical system and improve orientation in the future were discussed. This focus method could obtain long focal length and high power density focus spot, which can meet the light source requirement of laser cladding and surface treatment.关键词：LD stack;ZEMAX;beam shaping;beam focus112|245|0更新时间：2020-08-12
- 摘要：A mathematic model of LED heatsinks in greenhouses was established by the condition that the heat conducted into the fin heat equals the total heat from the air convection and the condensation of wet air. The air physical parameters under the worst condition were obtained by the physical simulation model of the greenhouse environment established by experiment and simulation. After obtaining the specific air physical parameters, combined with the constructed mathematical model, the temperature values of the key nodes of a 150 W plant growth LED lamp's heatsink suspended at the height of 2.5 m in the middle of the greenhouse were calculated in the worst case. The correctness of the model was verified by experiment and simulation, the data show that the relative error is not more than 5%, thus this has a positive effect for the design of LED lamps' heatsink for greenhouse.关键词：LED heat dissipation;optical device;mathematical model of temperature distribution;greenhouse environment;numerical simulation116|193|0更新时间：2020-08-12
- 摘要：The transmitting power of monochromatic infrared LED device is affected by such factors as transmission distance, operating current of light source and operating frequency, and all factors should be considered as the influencing factors of non-steady change. Through the experimental calibration and curve fitting to establish its impact model, we can further optimize the multi-parameter system through the biogeography optimization algorithm to directly determine the optimal parameter conditions. The use of biogeography optimization algorithm is a global optimization algorithm, which is very suitable for the comprehensive treatment of different physical mechanisms of various external factors on the monochromatic infrared LED device transmit power. The method can solve the bottleneck problem of paper moisture measurement technology and improve the measurement accuracy.关键词：monochrome LED light source;infrared;biogeography optimization algorithm;moisture;paper122|218|0更新时间：2020-08-12
- 摘要：In order to improve the illumination uniformity of LED array light source, a new way to design 3D LED arrays was proposed. At first, the formulas of LED array's illuminance on the target panel were derived and a mathematical model was then deduced in order to measure LED array's illumination uniformity. Then, a 2D circular LED array and a 2D square array were designed based on the way put forward by Ivan Moreno. The spatial positional parameters of the LEDs in the arrays were further optimized by the fruit fly optimization algorithm, and the standard deviation of illuminance on target panel was set as the taste concentration decision function of fruit fly optimization algorithm. The lower value the taste concentration decision function could obtain, the higher illuminance uniformity the optimized 3D LED array would have. The whole simulation process was carried on by the MATLAB software. In this way, the three-dimensional optimization of LEDs' locations in the arrays was accomplished, which made the illumination uniformity of the LED arrays much higher. At last, the TracePro optical software was adopted to imitate and test the illuminating effect of the optimized 3D arrays. The results of this experiment show that, after being optimized by the fruit fly optimization algorithm, the illumination uniformity of the optimized 3D circular LED array increased to 96.0%, which is 25.3% higher than the optimized 2D one, and that the illumination uniformity of the optimized 3D square LED array increased to 97.4%, which is 7.7% higher than the optimized 2D one. The results prove that this new optimization method is practicable, and compared to the traditional optimization methods, this new method is more efficient as the LED arrays are allowed to be optimized automatically by computer program, which greatly reduce the cost of time, material and manpower.关键词：LED array;fruit fly optimization algorithm;illumination uniformity;optimization110|251|3更新时间：2020-08-12
- 摘要：The oxygen sensing transistor characteristics of a conjugated polymer based on bis(2-oxoindolin-3-ylidene)-benzodifuran-dione and bithiophene (PBIBDF-BT) were investigated. The devices depicted both hole-and electron-carriers transport sensing properties in different oxygen atmospheres, where characteristics like drain current, mobility(μ) and subthreshold swing(SS) were tuned through the absorption/desorption processes of oxygen into the semiconductor layers. Experimental results indicate that the drain current, μ and SS based on the PBIBDF-BT polymer TFTs changed by -52.7%, -51.3% and 48% for P-channel, while changed by 42.3%, 59.5% and -39% for N-channel as the vacuum from 0.7 Pa (oxygen volumn fraction~5.3×10-6) to 0.08 Pa (oxygen volumn fraction~6×10-7). As the oxygen volumn fraction decreases from~8×10-7 to~6×10-7, the drain current of P-channel and N-channel increased by -45.9% and 31.1%, respectively. PBIBDF-BT polymer TFTs show bipolar detection of oxygen, and has a low oxygen detection line.关键词：OTFT;donor-acceptor conjugated polymers;ambipolar transmission;oxygen detection124|187|2更新时间：2020-08-12
- 摘要：In order to improve the performance of InSb infrared photo detectors operating at room temperature, a hetero-junction structure of GaSb/InSb/InP was proposed, and the contribution of Auger mechanism and Shockley-Read-Hall(SRH) mechanism to the leakage current was investigated. A theoretical model was established using TCAD tools, to obtain the band structure and carrier distribution. Then a simulation of the suppression of Auger mechanism under reverse bias and the total leakage current including Shockley-Read mechanism with different impurity concentrations was proceeded. The simulation was based on the carrier continuity equations, combined with the drift-diffusion transport model. Finally, samples were prepared using LP-MOCVD technique and a test of leakage current was carried out, and an analysis of the theoretical model and experiment data was presented. Experimental results indicate that the main limitation of the devices' performance is SRH mechanism, and there is a well fit of the theoretical model with the experiment data. The leakage current of the sample is 0.26 A·cm-2, and R0A is 0.1 Ω·cm2. R0A of the device increases by an order of magnitude compared to the homo-junction structure, and the device is close to practical level.关键词：InSb;infrared detector;un-cooled;recombination mechanism;leakage current137|204|0更新时间：2020-08-12
- 摘要：In order to passivate the defects of the perovskite surface and improve the viscosity and film-forming properties of the PCBM solution so as to enhance the performance of device, the non-fullerene acceptor molecules(ITIC) and electron-rich poly(n-vinylcarbazole) (PVK) are used as additives of PCBM film. As a result, the interface morphology and the performance of PCBM are optimized by adjusting the content of ITIC and PVK. The optimal device is obtained when the ITIC content is 6%(mass fraction). Compared with the control device without additives, the power conversion efficiency(PCE) is increased from 5.26% to 9.93%, with no hysteresis. It is found that the introduction of ITIC and PVK improves the film-forming properties of PCBM. Moreover, the surface defect state of perovskite is passivated. The synergy is beneficial to the charge transport and separation. In summary, the addition of PVK and ITIC inhibits the moisture and oxygen in the atmosphere into the device and improves the stability of the device.关键词：perovskite solar cells;interface engineering;hole-blocking;charge separation interfacial contact179|219|0更新时间：2020-08-12
- 摘要：In order to obtain the relationship between the position of the transmission peak of the photonic crystal defect and the refractive index(concentration) of the solution, the model of (AB)NC(AB)N one-dimensional photonic crystal was constructed in this paper. The transmission spectra of the one-dimensional photonic crystal were numerically simulated and analyzed by the finite difference time domain method. The results show that there is a strict linear relationship between the refractive index and the concentration of sucrose solution and the peak position of photonic crystal. The position of the transmission peak changes with the percentage of solution concentration. The solution measurement method of solution refractive index measurement sensitivity up to 498.087 nm/RIU. This provides a reference for the design and manufacture of photonic crystal solution refractive index and concentration measurement sensor, which is helpful for the promotion of the solution concentration detection sensor in practical application.关键词：photonic crystals;defect;transmission spectrum;solution concentration;finite difference time domain method159|346|0更新时间：2020-08-12
- 摘要：Double-tridentate ligand LD was synthesized by 5-aminophthalic acid through esterification, hydrazinolysis and Schiff's base reactions. Then, a novel metal-organic macrocyclic LD-Zn was built by the assembly of LD and zinc ions for the recognition of glucosamine. The detection mechanism of glucosamine with LD-Zn was studied by UV-Vis, 1H NMR and ESI-MS. The results of 1H NMR and ESI-MS indicate that the glucosamine molecules could enter the LD-Zn. Moreover, 1:1 stoichiometric host-guest complexation between glucosamine and LD-Zn was formed. UV-Vis spectra show that the intensity of the absorption peak at 373 nm increased significantly after addition of glucosamine into LD-Zn. However, the absorption intensity at 269 nm and 303 nm decreases. The equilibrium constant K reaches 4.19×103 L/mol, and the minimum detection limit is 5.0×10-6 mol/L. For comparison, the detection tests of glucose and triethylamine with LD-Zn were carried out. The UV-Vis spectra do not show any response when glucose and triethylamine are added to LD-Zn. These results indicate that the structure of glucosamine is more compatible with the cavity of the macrocycle LD-Zn compared to glucose and triethylamine. The recognition of glucosamine by using LD-Zn is not attributed to pure hydroxyl(hydrogen bonding) or amino(alkaline), it is mainly caused by the joint effect of confined cavity of LD-Zn molecular and hydrogen bonds of amino.关键词：glucosamine;macrocyclic compound;spectral analysis;detection119|202|0更新时间：2020-08-12
- 摘要：For a φ2 020 mm main mirror, in order to ensure that the spatial infrared camera main reflector has good surface shape accuracy and high first-order natural frequency, a targeted study of its supporting structure was conducted. According to the size of the mirror shape and shape accuracy requirements, the back of the mirror support was determined. It was designed to support the main reflector that a flexible structure with two flexible ways connected in series, and determined the maximum stress position of the flexible link. The finite element method was used to simulate and analyze the mirror assembly in the coupled state of force and heat. The results show that the RMS value of the maximum surface shape error of the mirror is 27.02 nm and the first-order resonant frequency of the component is 95 Hz. The finite element analysis was performed on the shape of the mirror when the camera was in the mounted state, and the analysis results showed that the design requirements of the main reflector were satisfied.关键词：infrared system;large aperture;main mirror;finite element analysis114|30|2更新时间：2020-08-12
- 摘要：The high speed TV measuring instrument mainly completes the task of measuring the lateral drift, the trajectory of the initial flight section with high precision, and recording the scene at high frame rate in the process of missile and rocket firing, taking off and leaving the tower. In order to meet the requirements of the space target measurement and continue to improve the optical measurement and control level of China's space range, a continuous zoom optical system with a focal length of 25-350 mm was designed. The system can change the focal length of the lens and adjust the field of view of the camera according to different task requirements and station conditions, so as to ensure that the target is imaged in a certain proportion in the field of view. In addition, the system increases the tracking and measuring distance of high speed TV measuring instrument, and effectively solves the problems of reflection, double shadow and interference fringes on the stored image in the camera of fixed focus optical system.关键词：high speed TV measuring instrument;optical system;space range108|297|0更新时间：2020-08-12
- 摘要：Taking advantage of the special oxidation property of hypochlorite, two novel coumarin-type fluorescent probes (compound C2 and C4) were synthesized for the rapid detection of ClO-. By virtue of its special oxidation property, both probes displayed high selectivity for ClO- over other anions. Upon the addition of ClO- anion, probe C2 displays extraordinary fluorescence quenching, which is beneficial to the production of a high signal output during detection process. Differently, probe C4 displays apparent enhancement in fluorescence emission spectra.关键词：probe;hypochlorite;fluorescence;selectivity;rapid detection118|117|1更新时间：2020-08-12
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