最新刊期
卷 40 ， 期 7 ， 2019
- 摘要：The red upconversion luminescence of lanthanide-doped fluoride nanocrystals has great potential applications in the fields of color display, biological imaging, biomedicine, anti-counterfeiting, especially the small size red upconversion nanocrystals have important application in biomedicine and biological imaging. In this work, a series of NaGd0.78-xF4:Yb/Ho/Cex(x=0%, 5%, 10%, 15%, 20%, 30%) upconversion fluorescent nanocrystals were successfully synthesized by solvothermal process. The phase structure, morphology and fluorescence properties of the products were characterized and studied by using X ray powder diffractometer(XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM) and fluorescence spectrometer. The product has uniform morphology and good dispersibility, showing hexagonal phase. The particle size is about 15-40 nm. With the increase of Ce3+ doping, the particle size increases. Under the excitation wavelength of 980 nm, the upconversion of Ho3+ red light increased significantly, the green light weakened with the increase of concentration of Ce3+ from 0% to 30%, the ratio of red light and green light increased from 0.122 4 to 3.219 3, increased by nearly 26 times, which realized the conversion of green to red. Finally, the possible upconversion emission mechanism between Ho3+ and Ce3+ ions is discussed in detail.关键词：NaGdF4;upconvensition;Ce ions161|185|2更新时间：2020-08-12
- 摘要：In order to obtain a single matrix white light emitting material, the Tm3+/Tb3+/Eu3+ doped borate glass ceramics were prepared by melting and crystallization method. The microstructure, spectroscopic characterizations and luminescence properties of the samples were characterized by X-ray diffraction diffractometer(XRD) and transmission electron microscope(TEM), ultraviolet-visible light detector and fluorescent spectrometer. The experimental results show that the single crystalline phase BaAlBO3F2 is precipitated after heat treatment of (500℃+2 h)+(550℃+2 h). Under 363 nm excitation, the single doped Tm3+, Tb3+ and Eu3+ samples emit blue, green and red light, respectively. Enhanced emission intensities of glass ceramic are obviously observed compared to glass sample. The color coordinates of glass ceramic samples easily change from blue light (0.313 4, 0.347 7) to warm white (0.388 6, 0.337 3) by altering concentration of Eu3+. When the concentrations of Tm3+, Tb3+, Eu3+ are 0.4%, 0.8% and 0.2%, respectively, the color coordinate (0.333 9, 0.335 7) and color temperature (5 427.92 K) of glass ceramic sample are close to that of standard white light (0.333 3, 0.333 3; 5 454.12 K). The results of fluorescence spectra and decay curves demonstrate that the energy transfer of Tm3+→Eu3+ and Tb3+→Eu3+ exists. The as-prepared glass-ceramic materials are promising to be applied to white light-emitting diodes and other optical devices.关键词：glass-ceramics;white light emitting diodes;photoluminescence;energy transfer182|120|2更新时间：2020-08-12
- 摘要：The Eu3+ doped Y3Al5O12:Ce3+ phosphor-in-glasses(PIGs) was prepared by crystallization and low temperature co-sintering. The prepared samples were tested by energy dispersive X-ray and photoluminescence spectroscopy, indicating that the rare earth ions Eu3+ and YAG:Ce3+ phosphors have been incorporated into the PIG. YAG:Ce3+ PIG with different content of Eu2O3 is packaged in a laser illumination device with a driving current of 100 mA. It is tested by STC-4000 fast spectrometer and PMS-80 visible spectrum analysis system, doping mass fraction 1% YAG:Ce3+ composite mass fraction 9% Eu3+ phosphor-in-glasses encapsulated laser lighting device luminous efficacy is 267.1 lm/W. As the current of laser illumination devices increases, the color rendering index increases gradually, but the increase is small.关键词：crystallization;low temperature co-sintering;phosphor-in-glasses;laser lighting device265|207|8更新时间：2020-08-12
- 摘要：Eu2+ doped 12CaO·7Al2O3 (C12A7:x% Eu2+) conductive phosphors with different concentrations were synthesized by a melting solidification method. Upon 254 nm UV excitation, we can observe a broad blue emitting band peaked at 444 nm, which originates from the 4f65d1-4f7 transition of Eu2+. As the Eu2+ doping concentration is 1.0%, the strongest emission intensity can be achieved. The conductive performance of Eu2+ doped 12CaO·7Al2O3 phosphors can be attributed to the generation of encaged electrons and the calculated encaged electron concentration is~3.40×1019 cm-3. After the conductive phosphor was annealed in air, its photoluminescence intensity increased with increasing the amount of encaged O2- anions (i.e. decreasing the amount of encaged electrons). Our results suggest that C12A7:Eu2+ blue emitting conductive phosphors have a potential application in field emission displays.关键词：rare earth ion;blue emitting;conductive phosphor;FEDs143|140|1更新时间：2020-08-12
- 摘要：Ho3+/Yb3+ co-doped glass ceramic sample was prepared with the molar ratios of 52SiO2-8Na2CO3-16Al2O3-33NaF-3LuF3-0.15Yb2O3-0.03Ho2O3 by the high temperature melting method in 1 500℃. The spectrum property was studied by using Judd-Ofelt theory. Spectral strength parameters Ωλ(λ=2, 4, 6) were computed based on the absorption peak's area of the absorption spectrum. The theoretical oscillator strength and the experimental oscillator strength were calculated according to the spectrum strength parameters,and the root mean square deviation (δrms) of them was 8.23×10-7. The parameters such as transition probability, decay branching ratios and level lifetime of Ho3+ were obtained. The result shows that the lifetime of metastable level 5I7 was longer of 0.28 ms, which was suitable for up-conversion intermediate level. And the decay branching ratio of 5I6→5I8(corresponding to the wavelength of 1 167 nm) was the most of 90.90%. Under the excitation of 980 nm diode laser, up-conversion luminescence was observed at the wavelength of 550 nm and 650 nm, corresponding to the radiative transitions of Ho3+:5S2,5F4→5I8 and 5F5→5I8, respectively. The two-photon absorption of three emission peaks was determined by the fitting curve graph of sample up-conversion emission power and the laser pumping power, when absorption of the photon number in turn was 2.16 and 2.18.关键词：glass ceramic;up-conversion;Judd-Ofelt theory;two-photon absorption183|145|5更新时间：2020-08-12
- 摘要：The effect of Ni on the contact performance of Ag/p-GaN interface is studied by the method of ‘Ni-assisted treatment’. The photoelectric properties of Ag/p-GaN interfacial are investigated by means of transmission line method(TLM), UV spectrophotometer(UV), X-ray photoelectron spectroscopy(XPS) and secondary ion mass spectrometer(SIMS). The results show that a small amount of Ni remains on the surface of p-GaN after Ni-assisted treatment and exists in the form of Ni2O3. The binding energy peak of Ga 2p3 on the p-GaN surface shifts 0.3 eV in the direction of low energy, which improves the Ohmic contact performance between Ag/p-GaN after Ni-assisted treatment. In our opinion, the Ni at the interface will preferentially combine with the O of Ga2O3 on the surface of p-GaN to form Ni2O3, thus reducing the Fermi level on the surface of p-GaN and improving the Ohmic contact performance between Ag/p-GaN.关键词：Ag/p-GaN contact;Ni-assisted treatment;Ni interlayer;surface Fermi energy159|209|1更新时间：2020-08-12
Synthesis and Properties of Materials
- 摘要：With many advantages, ultraviolet light-emitting diode(UV LED) packages have been widely applied in many beyond-lighting areas, including healthcare, disinfect, environmental protection and sensing. By using both simulations and experiments, this paper investigates the thermal stabilities and high temperature ageing reliability of near UV LED devices with three different packaging structures. The results indicate that, the radiation power and forward voltage of all samples show a downward trend with the increase of substrate temperature, but the downward trend of UV LED with flip-chip packaging structure is significantly less than that of wire bonding UV LEDs; the reliability test under the 55℃ and constant rated current condition shows that the luminous flux, radiation power and color coordinate of flip-chip type UV LEDs are relatively stable than those of wire-bonding type UV LEDs. Generally, this study can conclude that the flip-chip packaging structure with lower thermal resistance, small size and long life can improve the optical and thermal stabilities and reliability of UV LEDs.关键词：near ultraviolet LED;packaging;photothermal properties;thermal stability;reliability183|299|1更新时间：2020-08-12
- 摘要：TiO2 array was synthesized by hydrothermal method. The scanning electron microscopy(SEM) and X-ray diffraction(XRD) are used to detect their morphology and structure. The average diameter of TiO2 nanorods was increased from 100 nm to 200 nm, when the hydrothermal reaction time changed from 4 h to 8 h. UV-vis spectra were used to detect their absorption properties. The TiO2 array with shorter diameter shows blue shift of absorption edge and broadened band gap. The band gap of TiO2 nanorod was decreased from 3.09 eV to 2.97 eV, when the hydrothermal reaction time changed from 4 h to 8 h. Photoluminescence spectra were used to detect their optical properties. Near absorption edgee mission(about 382 nm), self-trapped exciton emission(about 420 nm), bound exciton emission(about 456 nm), and defect site emission(about 492 nm) are obtained under the examination by PL spectra.关键词：hydrothermal method;TiO2 array;optical properties145|362|2更新时间：2020-08-12
- 摘要：In order to obtain high laser pulse energy, a laser amplifier system was designed. The parameters of the amplifier system are studied such as the output energy, pulse width, energy stability and output pulse width. First, the analysis of the four-level laser rate equation is carried out, and the relations between pump energy,storage energy, and gain coefficient are derived. Then, the system design of the laser amplifier is given, and the experimental verification is carried out. Finally, the performance index of the output laser is tested. Experimental results indicate that, at the size of the Nd:YAG crystal rod of ? 8 mm×100 mm, the doping concentration Nd3+ of 1.1%, the pump maximum power of 24 kW, the semiconductor thermoelectric refrigeration with three maximum power of 66 W, the repetition frequency of 10 Hz, the pump current of 80 A, the pump pulse width of 200 μs, we obtained the output of the laser with the maximum pulse energy of 1 050 mJ at a wavelength of 1 064 nm, a pulse width of 10 ns and an output energy instability of 3%. The beam qualities M2 horizontal and vertical directions are 3.9 and 4.8, respectively, through the beam quality diagnostic instrument M-200S. It can satisfy the system requirements of high energy, without water-cooling, stability and reliability.关键词：diode-side-pumped;amplifier;high energy;thermoelectric cooler232|315|1更新时间：2020-08-12
- 摘要：A blue light LED epitaxial wafer with InGaN/GaN MQW structure was prepared on an Al2O3 (0001) substrate by MOCVD. The 400 mW semiconductor laser with a center wavelength of 405 nm was used as the excitation light source. The PL-spectrum at different temperatures was measured by the self-built 100-330 K low-temperature PL spectrum measurement device and the 350-610 K high-temperature PL measurement device. The peak energy and the relative intensity of InGaN/GaN MQW main luminescence peak, the phonon concomitant peak and the n-GaN yellow band peak, as well as the temperature dependence of the FWHM in the range of 100-610 K were studied by Gaussian peak differentiating and imitating. The results showed that in the temperature range of 100-330 K, the peak energy of the main luminescence peak and the phonon concomitant peak of the epitaxial wafer, as well as the temperature dependence of the FWHM displayed S and W-shaped changes respectively; the complete heating distribution temperature of the carrier was about 150 K; the transition temperature of local carriers from non-heating to heating distribution was 170-190 K; in the high temperature ranged 350-610 K, the changes in peak energy of InGaN/GaN MQW with temperature variation satisfied the Varshni empirical formula. In the In-doped process of MOCVD epitaxial growth, the PL spectrum could be measured by deliberately cooling the temperature; the amount of In-doped was calculated in real time; and the epitaxial wafer growth was monitored online. The above results can be used for the study of PL luminescence mechanism of epitaxial wafers, development of high-temperature online PL spectrum measurement equipment, real-time monitoring of In-doped and so on.关键词：GaN;MQW;LED;epitaxial;photoluminesecence219|441|0更新时间：2020-08-12
- 摘要：In this article, an optical software of TracePro was used to simulate the crosstalk of LED autostereoscopic display. Based on analyzing the design theory of two viewing-point LED autostereoscopic display, the LED model lighting pixel area is 2 mm×2 mm, and the black matrix area is 1 mm×1 mm. Assuming that the best view distance is 5 m, we calculate the silt and barrier width are both 2.87 mm. With these parameters, we can model the crosstalk of LED autostereoscopic display to compute and qualitatively analyze the illuminance of left and right view. With normalizing the illuminance, we found different uniformity distribution will cause dizzy phenomenon. Finally, according to the measurement method of crosstalk and the crosstalk of left and right simulation illuminance, we also get the crosstalk value of the LED autostereoscopic display, which is 42.4% obtained by Origin 9.1 software. This supplies the theory and technology method to improve the design and performance of LED autostereoscopic display.关键词：stereoscopic display;LED autostereoscopic display;simulation;crosstalk178|475|1更新时间：2020-08-12
- 摘要：In order to reduce the temperature of the active region of the high-power single-tube semiconductor laser, increase the heat dissipation performance of the package structure, and reduce the cost of the device package, a high-power semiconductor laser package structure using a high thermal conductivity graphite sheet as an auxiliary heat sink is proposed. Using finite element analysis, the use of graphite sheets as auxiliary heat sinks has been studied, and the packaged devices have lower thermal resistance and better heat dissipation. The effect of the variation of the width dimension of the transition heat sink copper-tungsten alloy and the auxiliary heat sink graphite on the active region temperature of the semiconductor laser was investigated. Compared with the traditional structure using copper-tungsten alloy as the transition heat sink, the new package structure has a junction temperature of 4.5 K and a thermal resistance of 0.45 K/W. According to the calculation, the maximum output power of the laser is 20.6 W. Under the guidance of the research results, the structural dimensions of copper-tungsten alloy and graphite can be determined to achieve the best heat dissipation effect.关键词：high powder semiconductor laser;heat dissipation;graphite heat sink;finite element analysis;package structure179|331|3更新时间：2020-08-12
- 摘要：The effects of different kinds of interface treatment on the characteristic of AlGaN/GaN MIS-HEMTs were studied in this paper. N2 and NH3 plasma pretreatment were used to improve the interface quality. The results show that N2 plasma pretreatment could reduce the current collapse of devices. By optimizing the time of N2 plasma pretreatment, it was found that the dynamic characteristic of devices with 10 min the pretreatment was improved, while that of 30 min was degraded. As a gate dielectric intercalation layer, the annealed AlN interlayer can effectively improve the dynamic characteristic of the device. The Vth hysteresis was decreased from 411 mV to 111 mV, and the device current collapse factor was reduced from 42.04 to 4.76 after under OFF-state VD stress of 900.关键词：current collapse;AlN gate dielectric insertion layer;interface treatment;AlGaN/GaN high electron mobility transistors184|308|0更新时间：2020-08-12
Device Fabrication and Physics
- 摘要：In order to study the effect of the interaction between drugs and pepsin(PEP) on the pharmacodynamics and digestive ability of stomach, the spectral determination was established under simulated physiological conditions. At 298, 310 and 318 K, the interaction mechanism between pioglitazone hydrochloride(PGH) and PEP was studied by fluorescence, synchronous fluorescence and molecular docking simulation. The results showed that a stable 1:1 complex was formed between PGH and PEP by electrostatic force and hydrogen bonding in a static quenching manner. Tyrosine residues(Tyr) and tryptophan residues(Trp) in PEP were involved in the reaction. The binding of PGH-PEP had positive cooperativity effect on the subsequent ligands. The results showed that when patients took PGH 15-45 mg, the drug binding rate in gastric juice was 0.0013%-0.0032%, which was very small, that is, the combination of PGH and PEP had little effect on PGH. The binding rate of PEP was 69.76%-87.37%, that is, PGH reduced the free PEP by 69.76%-87.37%, indicating that PGH would affect the digestive function of the patients. Molecular docking technique showed that the best binding site between PGH and PEP was located at the catalytic active site of PEP, and the interaction between them changed the microenvironment of amino acid residues in PEP catalytic active center.关键词：pioglitazone hydrochloride;pepsin;interaction mechanism;fluorescence spectroscopy;molecular docking169|231|0更新时间：2020-08-12
- 摘要：Aiming at the demand for joint determination of total phosphorus and total nitrogen in surface water and urban sewage, the principle of joint determination is proposed based on the national standard method. The sequential monitoring system and micro-control technology were used to establish a multi-range online monitoring system for total phosphorus and total nitrogen in water, and the determination of total phosphorus and total nitrogen index was completed. The total phosphorus index is measured in the range of 0-1.2, 1.2-2.5, 2.5-5 μg·mL-1. The total nitrogen index is measured in the range of 0-10, 10-20, 20-40 μg·mL-1. The measurement range covers the standard limits of total phosphorus and total nitrogen in the surface water environment I-V water and urban sewage treatment plant discharge standards. A regression model for determination of total phosphorus and total nitrogen was established by alternating least squares fitting algorithm. The experimental results show that the correction coefficient of the model is more than 0.996 4. The relative standard deviations of TP and TN repeatability were 1.36%-3.84% and 0.78%-3.69% respectively. Comparison of actual water samples in seven reservoirs in Guizhou, the relative error of total phosphorus is below ±3.7838%, the relative error of total nitrogen is below ±3.69%. The system runs steadily, and can accurately and efficiently analyze the total phosphorus total nitrogen index of different surface water samples, and provide technical support for environmental protection and sewage discharge, especially for laboratory, station type and portable on-line water quality monitoring.关键词：multi-range;total phosphorus;total nitrogen;Lambert-Beer law;on-line monitoring;photodiode178|221|5更新时间：2020-08-12
- 摘要：The fluorescence probe for Mg2+ was prepared with 2-amino benzene and imidazole and 7-hydroxyl coumarin as the basic raw material. The product composition was characterized in detail by means of nuclear magnetic resonance spectrum and mass spectrum, and then through the test and analysis by fluorescence emission spectrum, the various properties of the probe were understood. The results showed that the probe has good selectivity to Mg2+ in the mixed solution of MeOH:H2O=1:1(V:V) and there are no other metal ions(Ca2+, Na+, Li+, K+, Cu2+, Fe3+, Zn2+, Ni2+, Mn2+, Ba2+, Cd2+, Cr3+, Ag+, Al3+, Hg2+, Co2+, Pb2+) interference. The probe is reversible to Mg2+, the detection limit is 7.3×10-8 mol/L. Through the study on performance of the probe,the probe can complete the detection of Mg2+. The probe has potential application value in the fields of biomedical, environmental science and analytical chemistry, etc.关键词：coumarin;fluorescent probe;metal ions;detection limit188|99|5更新时间：2020-08-12
Luminescence Applications and Interdisciplinary Fields
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