最新刊期
卷 39 ， 期 7 ， 2018
- 摘要：X-ray storage phosphors 12CaO·7Al2O3:Pr3+ (C12A7:Pr3+) with different doping concentrations were synthesized by a combustion method. For C12A7:0.3%Pr3+ phosphor, the strongest intensity of the emission peak at 486 nm, originating from 3P0-3H4 transition of Pr3+, can be obtained upon 232 nm excititation. After the annealing in vacuum, the number of encaged O2- anions decreased, while the amount of empty cages increased. Thus, it led to the increased number of traps and the enhanced photo-stimulable luminescence(PSL). The thermoluminescence(TL) analysis showed that there existed two deep traps in the phosphors and the trap depths were~0.69 and~0.80 eV, respectively. In particular, the annealing in vacuum led to the deeper trap depths, the increased number of traps and the improved storage properties. Upon X-ray irradiation(applied dose:5.2 Gy), a blue image with high resolution was obtained by 808 nm stimulation. Our results suggested that the C12A7:Pr3+ phosphors have potential application in the field of computed radiography.关键词：photoluminescence;phosphor;rare earth ion;thermoluminescence114|33|4更新时间：2020-08-12
- 摘要：The nanostructures composing of Na1-xKxErF4@NaLuF4 core@shell were synthetized with 0%-8% K+ doping mole fraction in the cores. XRD results reveal that all of the nanoparticles are the hexagonal structure. The research results show that the intensity of UCL at~650 nm increases at first and then decreases with K+ concentration under 980 nm excitation. The intensity is enhanced 3.7 times with 4% K+ doping, compared with that of NaErF4@NaLuF4 core@shell without K+ doping. Furthermore, the slopes of relationship between UCL intensity and pumping power are from 1.91 to 1.76, for the two nanostructures undoped and doped with 4% K+, respectively. Our results suggest that the strategy of K+ doping in NaErF4@NaLuF4 nanoparticles is an efficient solution to improve the luminescence efficiency of NaErF4@NaLuF4 nanosystem.关键词：rare earth ions;upconversion luminescence;K+ doping;luminescence efficiency175|120|0更新时间：2020-08-12
- 摘要：Li1.0Nb0.6Ti0.5O3:Eu3+ red phosphor was synthesized by sol-gel method. The influences of the sintering temperature, the sintering time and the Eu3+ doping concentration on the luminous properties of the samples were discussed. The properties of the samples were characterized by X-ray diffraction(XRD) and photoluminescence spectroscopy, respectively. The results show that the samples are consist of "M-phase". Under the excitation of 466 nm, the orange emission at 593 nm and the red emission at 612 nm can be observed. The emission intensity increases with the increasing of the sintering temperature firstly and then decreases. The optimum sintering temperature is about 850℃. Moreover, the emission intensity increases with the increasing of the sintering time firstly and then decreases. The relatively high emission intensity of the sample can be obtained when the sintering time is 6 h. In addition, the optimal doping mass fraction of Eu2O3 is about 2.5%. Therefore, the red phosphor has potential application in the white-LED field.关键词：sol-gel method;Eu-doped;red phosphor;emission spectrum123|127|0更新时间：2020-08-12
- 摘要：Fluorescent materials P(CS-g-OC-CA)Ds with high fluorescence quantum yield(42.9%) were prepared by hydrothermal method using chitosan, citric acid, Octylaldehyde and N-(2-hydroxyethyl) ethylenediamine as raw materials. The P(CS-g-OC-CA)Ds were characterized by infrared spectroscopy, ultraviolet spectroscopy (UV), X-ray powder diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and photoluminescence spectra. The drug loading properties of the P(CS-g-OC-CA)Ds were studied using doxorubicin (DOX) as a model drug. When the degree of octane substitution is 76.42%, the optimal loading and entrapment efficiency of DOX are 49.6% and 47.4%, respectively. Notably, the amount and encapsulation efficiency of DOX can be controlled by controlling the degree of octane substitution. After loading, the micelles are approximately 80-90 nm in diameter. The fluid mechanics particle size is 114.3 nm, and the surface potential is +5.72 mV. In vitro release studies demonstrate a dual release phase from the drug-loaded micelles in pH 7.4 phosphate buffer, with a rapid first-phase release and a slow second-phase release of DOX. Cytotoxicity studies demonstrate that there is no obvious cytotoxicity of blank P(CS-g-OC-CA)Ds, and the survival rate of nasopharyngeal carcinoma (CNE-2) cells decreases with the increasing of the amount of drug-loaded micelles. These results show that the nanomicelles have a strong inhibitory effect on CNE-2 cells. In conclusion, the obtained P(CS-g-OC-CA)Ds are potentially useful as drug-delivery and fluorescence trace systems.关键词：chitosan;polymer carbon dot;fluorescence material;drug loading;DOX166|308|2更新时间：2020-08-12
- 摘要：A series of phosphors La1-xAlO3:xRE3+ (RE=Eu, Tb, Sm, Tm) were synthesized by sol-gel method. Techniques such as thermogravimetric and differential thermal analysis(TGA-DTA), X-ray powder diffraction(XRD), transmission electron microscopy(TEM), photoluminescence emission and excitation spectra were used to characterize the phosphors. The results showed that the synthesized samples were pure phase with trigonal crystal structure when the calcination temperature was from 800℃ to 1 200℃. Under UV light excitation, the doped rare earth ions exhibited f-f feature level transitions. The doped ions gave the strongest emission when the doped concentration (x) of Eu3+, Tb3+, Sm3+ and Tm3+ was 0.02, 0.04, 0.005 and 0.005, and gave red, green, orange and blue emission, respectively. Eu3+-Tb3+, Eu3+-Sm3+ and Eu3+-Tm3+ co-doped samples were likely to emit white light.关键词：sol-gel method;LaAlO3:Eu3+;Tb3+;Sm3+;Tm3+;luminescent properties107|153|3更新时间：2020-08-12
- 摘要：H-PAF(Micro-porous aluminum fluoride)is a porous fluoride with the specific surface area(SSA) of 20-200 m2/g, has a low melting point and high activity characteristics. It can lower the reaction temperature for more than 50℃ and improve the luminescence property of Eu2+:(Sr,Ca)AlSiN3 as a flux. In this paper, H-PAF was used as flux to synthesis Eu2+:(Sr,Ca)AlSiN3 phosphors. The reaction temperature decreased from 1 800℃ to 1 750℃, and the peaks of XRD patterns are more sharp, indicating better crystal crystallization. The white LED device was fabricated using Eu2+:(Sr,Ca)AlSiN3 red phosphor and Ga-YAG green phosphor, and the optical efficiency of Eu2+:(Sr,Ca)AlSiN3 was tested. It is found that the powder content of Eu2+:(Sr,Ca)AlSiN3 phosphor decreases by about 5% after adding PAF, and the luminous flux of the device increases by more than 2%.关键词：porous;fluoride;flux;specific surface area;high activity characteristic139|186|0更新时间：2020-08-12
- 摘要：In order to deposit a low stress SiO2 dielectric film on a GaSb substrate, the stress of SiO2 film deposited on GaSb substrate with larger lattice mismatch by plasma enhanced chemical vapor deposition(PECVD) was investigated. The SiO2 film was experimentally tested based on the curvature model by changing the process parameters of PECVD, such as deposition temperature, RF power, cavity pressure and gas flow ratio. And the stress was calculated by Stoney formula. The effects of these parameters on the stress of SiO2 film were analyzed in detail. At the same time, the causes and the mechanism of the stress generation as change of the process conditions compared with the stress of SiO2 film deposited on Si substrate were discussed. Experimental results indicate that the stress of SiO2 film deposited on GaSb substrate by PECVD is relatively small under the process parameters of deposition temperature of 300℃, RF power of 20 W, cavity pressure of 90 Pa, gas flow ratio of SiH4/N2O of 125/70 cm3·min-1.关键词：GaSb;plasma enhanced chemical vapor deposition(PECVD);SiO2 film;stress125|165|3更新时间：2020-08-12
- 摘要：In order to provide the theoretical basis for the application of VO2 thin films to anti-directional infrared countermeasures system, the phase transition characteristics of VO2 thin films in the infrared band were characterized by the transmittance modulation depth. At first, VO2 epitaxial mono crystalline thin films were prepared by molecular beam epitaxy(MBE), and then characterized by X-ray diffraction(XRD), atomic force microscope(AFM). It is found that it has (020) preferential orientation, high purity VO2 in the thin films, the surface of thin films is smooth, uniform and dense. The near infrared transmittance phase transmittance property is found to be outstanding by VU-Vis-IR measurement, however, it is less obvious in ultraviolet and visible light. We took an experiment that transmittance variation for mid-infrared from 25 to 70℃ temperature rising and cooling process based on two groups of VO2 prepared for 30 min and 40 min, respectively. The mid-infrared laser was used in the experiment with 3 459 nm wavelength, 50 ns pulse width, 50 kHz repetition frequency, and 0.14 W/cm2 power density. The two temperature hysteresis curves were compared. It is found that the transmittance modulation depth of mid-infrared of them both can reach over 60%, and the former group is about 4% higher than the latter group in transmittance modulation depth in mid-infrared. This indicates that the VO2 mono crystalline films prepared by the molecular beam epitaxial method have good mid-infrared transmittance modulation characteristics, and the modulation depth is related to film thickness. It is further demonstrated that it is feasible to put VO2 thin films into anti-directional infrared countermeasures system.关键词：molecular beam epitaxy(MBE);VO2 thin films;transmittance modulate depth;mid-infrared laser protection128|201|0更新时间：2020-08-12
- 摘要：A series of Ca2MgSi2O7:Dy3+,Tm3+ luminescent materials were synthesized by high temperature solid phase method. The samples were characterized by XRD structure, and the excitation spectra, emission spectra, color temperature and fluorescence lifetime were measured. The results show that Ca2MgSi2O7:Tm3+ exhibits blue luminescence under the excitation of 355 nm. The color coordinate in CIE1931 is x=0.165 9, y=0.082 2, and the color purity is 89%。Excited by the superposition excitation bands of Dy3+ and Tm3+ (349, 353, 365 nm), Ca2MgSi2O7:Dy3+,Tm3+ phosphors show bright white, cool white and warm white light, and the correlation color values are 5 193, 9 672, 4 685 K, respectively. In conclusion, Ca2MgSi2O7:Dy3+and Tm3+ can be effectively excited by 300-500 nm regions and emit white light produced by blue and yellow light combinations between 400-600 nm, shows that the system can be used as a luminescent material for white LED.关键词：Ca2MgSi2O7:Dy3+;Tm3+ phosphor;photoluminescence;white light LED;superposition excitation band118|166|5更新时间：2020-08-12
- 摘要：The effects of the host materials and electron transport materials on the blue organic light-emitting diodes was studied by researching the effects of energy level and triplet exciton on the performance of devices based on the structure of ITO/MoO3/NPB/TCTA/FIrpic:TCTA/FIrpic:X/Y/LiF/Al. The high quality double emission layers device with the peak efficiency of 23.78 cd/A was obtained when X and Y are TmPyPb and TPBI. The results showed that the distribution of exciton and energy transfer can be adjusted and influenced by host materials and electron transport materials.关键词：blue;double emission layers;material adapted;energy transfer173|192|2更新时间：2020-08-12
- 摘要：InGaN/GaN multiple quantum wells(MQWs) yellow light-emitting diodes(LEDs) were grown on patterned silicon substrate by metal org anic vapor deposition. The effect of diff erent quantum well growth pressure on the photoelectric properties of yellow light LED has been investigated.The crystal quality was characterized by high resolution X-ray diffraction(HRXRD) and fluorescence microscope(FL), and the photoelectric properties were characterized by using an integrated integrating sphere. the results review that increased pressure decreases In incorporation, but also enhances the uniformity, contributing to the lower point defects but roughness interface. The maximum of external quantum efficiency improves significantly under the pressure 4, 6.65, 10, 13.3 kPa, respectively 16.60%, 23.07%, 26.40%, 27.66%. However, it is noted that more efficiency droop appears with the growth pressure at 13.3 kPa. Under the working current of 20 A·cm-2, the EQE of A, B, C and D were 16.60%, 19.77%, 20.03% and 19.45%, respectively. The best photoelectric performance of the device can be obtained when the growth pressure is set to 10 kPa.关键词：MOCVD;InGaN/GaN quantum wells;yellow LED;growth pressure;photoelectric properties112|144|0更新时间：2020-08-12
- 摘要：A kind of flexible amorphous silicon doped tin oxide(SiSnO, STO) thin film transistor (TFT) with anti-bending property of polyimide as a flexible substrate was prepared by RF magnetron sputtering method. By comparing the performance of the devices with different annealing temperatures, it is found that the best device performance is achieved at 300℃, the field effect mobility is 2.71 cm2·V-1·s-1, the switching ratio is higher than 106 and the subthreshold swing is 1.95 V·dec-1, and the threshold voltage is 2.42 V. By measuring the output characteristics and transfer characteristics of the device at different radius of curvature(5, 10, 20, 30 mm), the device is still operating well under the four different radii of curvature.关键词：flexible;silicon doped tin oxide;thin film transistor133|229|1更新时间：2020-08-12
- 摘要：The concentrating efficiency and the energy uniformity of the concentrating system directly influence the generation efficiency of the unit module. In this paper, a high power condensing module system was studied. The system included a Fresnel lens and flat spherical micro prism. The Fresnel lens was designed by central wavelength correction method and through Zemax simulation,and the design of spherical flat lens was established. Finally, through the Zemax simulation, it is decided that the angle between the two sides is selected to be 117°, the distance g between the flat top and the spherical surface is 0.2 mm, and the curvature radius R of the spherical dome microprism is 10 mm. The condensing system as a whole has a condensing efficiency of 99.8% and an energy uniformity of 0.812. Experimental results show that the actual condensing efficiency is 83.1%.关键词：concentration efficiency;energy uniformity;Fresnel lens;spherical flat microprism;ZEMAX122|325|0更新时间：2020-08-12
- 摘要：Semiconductor laser chip and heat sink in the welding process will inevitably produce some holes in the solder layer. These voids will become larger in the electromigration and electromigration of indium. The local temperature of the chip rises rapidly, and affects the performance of semiconductor lasers. A three-dimensional finite element model of 808 nm single-tube welding semiconductor lasers with power of 10 W was established, and the relationship between void area, void thickness and void position was calculated. The results show that the voids formed in the active region of the edge of the chip have a more significant influence on the junction temperature of the chip. Finally, the relationship between cavity area and junction temperature was obtained. The importance of void ratio control was also demonstrated.关键词：thermal characteristics;voids;finite element;junction temperature143|212|0更新时间：2020-08-12
- 摘要：A high-pulse-energy, diode-pumped, solid-state Nd3+:Y3Al5O12 (Nd:YAG) two-pass amplifier system without water cooler was demonstrated in this study. The modulation of LD and Nd:YAG crystal rod and the use of thermoelectric cooler(TEC) in whole system aimed to make the system miniaturized. The cavity length was 280 mm. And a 350 mJ laser pulse was obtained with a pulse duration of 9.7 ns, a frequency of 10 Hz and a beam quality M2 of 7.7 and 12.3 for horizontal and vertical directions, respectively. A 740 mJ, 10 ns laser pulse for two-pass amplification was obtained.关键词：solid-state laser;high-energy;thermoelectric cooler(TEC);diode-side-pumped;MOPA123|198|2更新时间：2020-08-12
- 摘要：The metal-semiconductor-metal(MSM) structure ultraviolet(UV) photodetector was fabricated on the nonpolar AlGaN grown on r-sapphire substrates by metalorganic chemical vapor deposition(MOCVD) using high temperature treatments. The effects of passivation layers by adding SiO2 nanoparticles(SiO2-NPs) or SiO2 layers (SiO2-Ls) on optical and electrical properties of the nonpolar AlGaN-MSM UV photodetector were investigated systematically. The results indicate that the surface passivation of SiO2 is an important way to enhance the UV performance of the nonpolar AlGaN-MSM UV photodetector. The fabricated devices are characterized by measurements of the dark I-V characteristic and the spectral response. It was found that the dark current of the AlGaN-MSM UV photodetector decreased by 1-2 orders of magnitude by SiO2-NPs or by SiO2-L, which can lower to the order of nA. The detector exhibits a sharp cut-off wavelength at about 300 nm, the spectral response is improved 103 times and the ratio of UV to visible reaches as high as 105.关键词：passivation;nonpolar AlGaN;MSM;UV photodetectors115|231|0更新时间：2020-08-12
- 摘要：In order to meet the needs of professional and nonprofessional personnel about fast repairing the fault fiber laser in the practical engineering and production applications, a fast fault mode and fault cause analysis system was reaearched. First, the fault mode and fault cause of the damaged laser in actual use were collected as samples. The extended fault tree of fiber laser was established by the fault tree analysis and failure mode effect criticality analysis, i.e. the corresponding relationship between failure mode and fault cause was constructed. Then, Bayesian network was used to analyze and obtain the prior probability and posterior probability of each failure mode and fault cause. Using Python to write interactive window and call database data, the corresponding probability was calculated. Finally, the possible fault mode and correspond probability were output through interactive interface, so as to achieve rapid analysis of fiber laser fault. The analysis system simulation results coincide with the reality, calculating less than 1 s, so the system can basically meet the relevant personnel to guide the rapid troubleshooting and repair requirements.关键词：fiber laser;fault tree analysis;failure mode effect criticality analysis;Python151|534|1更新时间：2020-08-12
- 摘要：A dimming and calculation method of circadian factor is proposed in view of the importance and complexities of non-visual biological effects. When the spectral distribution of each of the three channels under the rated conditions is given, the illuminance, CCT and circadian factor of hybrid light at any ratio can be calculated easily. In test, three-channel hybrid light source is composed of three color temperature LEDs, and dimming with PWM on the principle of time sharing. At one testing distance, the spectral distribution of each single channel is measured independently first, and the theoretical illuminance, CCT and circadian factor of hybrid light in continuous gradient are obtained by the dimming and calculation method. Then, the actual illuminance, CCT and circadian factor of hybrid light are measured. Finally, the two illuminances, CCT and circadian factors got by theoretical and actual are compared along with an error analysis. The results show that the fitting line of the illuminance, CCT and circadian factor and the line described by the dimming and calculation method show a low difference in slope, which is below 6%, 2%, 3%,respectively, and the difference in intercept is below 2%, 5%, 3%, respectively. And there is no significant difference between the actual rhythm factor and the theoretical calculated rhythm factor under the significant difference test. It is shown that the dimming and calculation method can calculate the illuminance, color temperature and circadian factor of the hybrid light easily and effectively without measuring the spectral distribution of hybrid light when the spectral distribution of each single LED is given.关键词：circadian factor;dimming and calculation method;time-share PWM dimming pattern;three channels LED184|334|2更新时间：2020-08-12
- 摘要：Visible/near infrared spectroscopy(Vis/NIRS) is an effective tool for soil component detection. Wavelength selection plays an important role in predicting the soil properties of the visible/near infrared(Vis/NIR) model. Taking the 75 paddy soil samples of Ningxia Wuzhong area as the research object, the Vis/NIR spectra of soil samples were collected. The sample set partitioning based on joint X-Y distance(SPXY) method was used to divide calibration set and prediction set samples. Three different preprocessing methods, namely, Savitzky Golay smoothing(SG smoothing), multiplicative scatter correction(MSC), and standard normal variate(SNV), were applied to pretreat the spectral data. Then, three soil available nitrogen content prediction models were established by partial least squares(PLS) regression. The consequences of the three models and the model using raw spectral data were compared. On this basis, the genetic algorithm(GA), successive projections algorithm(SPA), competitive adaptive reweighted algorithm(CARS) and Random Frog(RF) were used to select key wavelength variables. Finally, the soil available nitrogen content prediction models were established by partial least squares regression based on different wavelength selection methods. Research shows that, due to the stability of the instrument, relatively small and uniform of the sample particle size, raw spectral data is achieved the best consequence; various wavelength selection methods can effectively reduce the number of wavelengths in the model, and the continuous projection algorithm is better than full spectrum model, the selected wavelength number is only 1% of the number of full spectrum wavelength and its prediction coefficient of determination(R2), root mean square prediction error and relative error analysis values were 0.726, 3.616 and 1.906. The research shows that wavelength selection method by SPA could predict the available nitrogen content in the paddy soil, provide a reference for development of soil available nitrogen sensor.关键词：soil;visible/near infrared spectroscopy(Vis-NIRS);available nitrogen;spectral pretreatment;wavelength selection187|254|9更新时间：2020-08-12
- 摘要：Mercaptopropionic acid capped CdSe/ZnS quantum dots(QDs) were synthesized in aqueous solution. The CdSe/ZnS QDs modified gold electrode was prepared. The electrochemical luminescence of this modified electrode was studied. Several experiment factors, such as pH of buffer solution, the concentration of CdSe/ZnS QDs, scan rate and rest time were selected. The results show that the CdSe/ZnS modified electrode has an obvious ECL signal of luminol systems in alkaline media, and norepinephrine can enhance electrochemical luminescence(ECL) signal of the luminol system. Based on these, a novel electrochemical luminescence method for the determination of norepinephrine was developed. Under the optimum conditions, ECL intensities had good linearity with the concentration of norepinephrine and the linear range was widely extended from 2.3×10-5-1.0×10-8 mol/L. The linear regression equation is ΔIECL=118.788CNE-15.333, and the correlation coefficient was 0.994 4. The detection limit is 0.33×10-8 mol/L.关键词：mercaptopropionic acid;CdSe/ZnS quantum dot;electrochemical Luminescence(ECL);norepinephrine(NE)140|352|1更新时间：2020-08-12
- 摘要：The Laplace transfer current density convolution finite difference time domain(LTJEC-FDTD) was used to study the medium of time-varying magnetic plasma. A Gaussian-derivative pulsed plane wave was simulated in magnetic plasma by the method of LTJEC-FDTD. The numerical results show that the method of LTJEC-FDTD not only ensure the accuracy but also has higher computational efficiency. By simulating the propagation characteristics of a Whistler wave in the one-dimensional time-varying magnetic plasma, a output wave with higher frequency and enhanced electric field is obtained after switch off the plasma source. Finally, a terahertz wave with 300 GHz is obtained which theoretically verifies that the terahertz wave can be generated from the microwave by the time-varying magnetized plasma. These conclusions provide some theoretical bases for the generation of terahertz wave.关键词：time-varying magnetic plasma;terahertz source;LTJEC;FDTD140|237|1更新时间：2020-08-12
- 摘要：A compact non-planar four-port channel drop filter was developed experimentally in the three-dimensional Woodpile photonic crystal with a complete band gap. It consisted of two waveguides separated by a defect in different layers of the photonic crystal. The property of frequency selecting of channel drop filter with sphere cavity, cube cavity, cuboids cavity and cuboids cavity rotating was discussed experimentally. The results show that the property of frequency selecting of channel drop filter can be realized whatever the cavity is symmetric or non-symmetric in the Woodpile structure. It indicated the output frequency can be effectually regulated by changing the symmetric of non-planar cavity. For a non-symmetric cavity, the output frequency can be adjusted as the rotation of the cavity. If the effective regulation mechanism is introduced, the output frequency can be adjusted continuously. The results provide a new idea and an important theoretical reference for the design of optical integrated devices.关键词：photonic crystal;Woodpile;drop filter127|132|0更新时间：2020-08-12
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