最新刊期
卷 39 ， 期 9 ， 2018
- 摘要：A series of novel double perovskite tellurate red-emitting phosphors Sr2ZnTeO6:xEu3+(x=0.05-0.40) were successfully synthesized by a high-temperature solid-state reaction method at 1 150℃. The phase structure, photoluminescence properties and thermal stability of the phosphor were investigated in detail. The phosphor shows dominant emission peak at 614 nm belonging to the 5D0→7F2 electric dipole transition under 464 nm excitation. The luminescence intensity keeps increasing with increasing the content of Eu3+ to 25%, and the critical transfer distance of Eu3+ was calculated to be 1.2 nm. The quenching temperature for Sr2ZnTeO6:0.25Eu3+ was estimated to be above 500 K. This spectral feature reveals high color purity and excellent chromaticity coordinate characteristics. Therefore, Eu3+-doped Sr2ZnTeO6 phosphors are potential red phosphors for blue chip-based white light-emitting diode and display devices.关键词：double perovskite;phosphor;Eu3+;tellurate184|83|1更新时间：2020-08-12
- 摘要：The photoluminescence properties and energy transfer mechanism of a color tunable phosphor NaTaOGeO4:Tb3+,Mn2+ were investigated in this paper. NaTaOGeO4:Tb3+,Mn2+ powder was synthesized successfully by solid state reaction method. The phase purity was checked using X-ray powder diffractometry(XRD). The excitation and emission spectra were recorded to elucidate the photoluminescence properties of NaTaOGeO4:Tb3+,Mn2+. Furthermore, the fluorescence lifetime measurements were performed. The emission spectrum of NaTaOGeO4:Tb3+ excited by 244 nm shows blue emissions at 380, 413, 436, 492, 544 nm, which are attributed to 5D3→ 7FJ and 5D4→7FJ(J=6, 5, 4) transition of Tb3+, respectively. The emission spectrum of NaTaOGeO4:Tb3+ excited by 277 nm shows green emissions at 492 nm and 544 nm, which are attributed to 5D4→7F6 and 5D4→7F5 transition of Tb3+. The emission spectrum of NaTaOGeO4:Mn2+ shows orange-red emissions at 576 nm, owing to 4T1→6A1 transition of Mn2+. With varying the ratio of the concentration of Mn2+ and Tb3+, a color tunable phosphor NaTaOGeO4:Tb3+,Mn2+ can be obtained.关键词：rare earth ions;transition metal;phosphors;color tunable;luminescence151|70|1更新时间：2020-08-12
- 摘要：In order to improve the water soluble and the hemostatic performance of chitosan, the chitosan(CS) was modified by carboxymethylation, and Ag+ and TiO2 with antibacterial action were introduced. In this way, carboxymethyl chitosan composite hemostatic material was prepared. Firstly, in chitosan, carboxymethyl was introduced, and carboxymethyl chitosan(CMCS) was prepared, then Ag+ and TiO2 were introduced, and Ag+-CMCS, TiO2-CMCS and Ag+-TiO2-CMCS composites were prepared, respectively. Then, FTIR, XRD and SEM were used to characterize the structure of composites. Finally, the coagulation and hemostatic properties of the complex were tested. There are characteristic absorption peaks of carboxymethyl chitosan sodium salt around 3 423 cm-1 and 1 380 cm-1 in the IR spectra of modified carboxymethyl chitosan. The XRD shows it is metals crystalline. The average diameter of CMCS is about 14.8 nm, Ag+ is 143.5 nm, nanometre TiO2 is 267.2 nm, and all of them are homodisperse. The properties of crour and hemostasis of Ag+-TiO2-CMCS are superior to Ag+-CMCS and TiO2-CMCS, while Ag+-CMCS and TiO2-CMCS also have an advantage over CMCS.关键词：carboxymethyl chitosan;modified;composite materials;characterization124|103|2更新时间：2020-08-12
- 摘要：A series of LaBO3:Eu3+ phosphors with Y3+ and Gd3+ ions different doping concentrations were prepared by sol-gel combustion method. The structure, morphology and luminescence are characterized. The results of XRD indicate that the structures of phosphors are related to doping ions and doping concentration of matrix. The results of emission and excitation spectra show that the luminescence intensity of LaBO3:Eu3+ phosphors is enhanced by appropriate proportion Y3+ and Gd3+ ions doping in hosts. Y3+ and Gd3+ optimum doping mole fraction is 1.5% and 12.5%, respectively. The 5D0→7F2/5D0→7F1 relative emission intensity ratios show that the local symmetry environment around Eu3+ ions is changed because of doping ions. The luminescence properties are influenced by the crystal structure and electronegativity of doping ion. In addition, the Gd3+ doping is more advantageous to the stability of structure and improvement of luminescence properties.关键词：sol-gel combustion method;LaBO3:Eu3+;phosphors;luminescence property149|61|2更新时间：2020-08-12
- 摘要：BaSi2O2N2:Eu2+ blue-green phosphor was synthesized by high temperature solid-state method. Under the excitation of blue light, BaSi2O2N2:Eu2+ phosphor emits blue-green light with peak wavelength at 488 nm. Co-doped with Mg2+ and Ge4+ ions, the thermal quenching property of BaSi2O2N2:Eu2+ was significantly improved, which helps to improve the aging performance of WLED. By using BaSi2O2N2:Eu2+ blue-green phosphor, Y3 (Al, Ga)5O12:Ce3+ yellow-green phosphor and CaAlSiN3:Eu2+ red phosphors, the Ra of the blue-chip based WLED reaches 96.5, and all the special color rendering indices (R1-R15) of the WLED are over 90, which meet the requirements of full spectrum WLED lighting.关键词：blue-green phosphor;white LED;full spectrum;color rending index276|135|4更新时间：2020-08-12
- 摘要：Mechanoluminescence(ML) materials SrAl2O4:Eu,Ho(SAOEH) were prepared via solid state reaction. The XRD results show that the as-prepared sample is mostly monoclinic SrAl2O4 phase. The SAOEH powder was mixed with high elastic resin to prepare ML thin film. The photoluminescent intensity of the ML film increases following the increase of film thickness. The SEM results reveal that SAOEH ML particles disperse uniformly in the resin. In order to detect the weld seam defects, the SAOEH ML film was pasted in the backside of welding steel plate. It can be found that the ML intensity in the weld region is stronger than that in any other region. In addition, the ML intensity is enhanced following the increase of film thickness and reaches the strongest when the film thickness is 0.9 mm. Furthermore, the SAOEH film can be utilized to realize a real-time response to the fracture. Combining with CCD camera, the visual detection of steel weld and location of the defect region during the cyclic test can be realized.关键词：SrAl2O4:Eu;Ho/resin films;mechanoluminescence;defect monitoring;fluorescence sensing190|74|2更新时间：2020-08-12
- 摘要：Cubic KY3F10:15% Yb3+,0.5% Tm3+,0.2% Ho3+ upconversion nanocrystals were synthesized by a simple hydrothermal method. Under the excitation of 980 nm, the upconversion luminescence with chromaticity coordinates nearby equal energy white was obtained. The analysis of the upconversion mechanism shows that the blue, green, and red emissions originate from the energy transfer from Yb3+ to Tm3+ and Ho3+, respectively. More importantly, it is found that the upconversion white emission shows favorable color stability. When the pump power increases from 688 mW to 1 688 mW, the aberration is only 0.027 5. The reason is that, on the one hand, the power dependences of the three primary colors are relatively close to each other. On the other hand, the power dependence of the blue emission gradually decreases as the pump power increases, while the power dependences of the green and red emissions remain unchanged. The saturation of blue emission may be related to the thermal effect caused by laser radiation.关键词：upconversion white emission;color stability;KY3F10;nanocrystals143|52|2更新时间：2020-08-12
- 摘要：A series of Ce3+/Tb3+/Sm3+ doped CaO-B2O3-SiO2 (CBS) luminescent glasses were prepared by melting method at high temperature. The microstructure and luminescentce properties of CBS glasses were characterized with Fourier infrared spectrometer and photoluminescence spectrometer. Purplish blue, green, and red emission bands were observed in the emission spectra of Ce3+/Tb3+/Sm3+ single-doped CBS glasses excited by 339, 378, 407 nm, respectively. These emission bands just meet the requirements of hybrid synthetic white light. The emission spectra and decay curves of Ce3+/Tb3+ and Ce3+/Sm3 co-doped CBS glasses have proved the existence of energy transfer. The average life time of Ce3+ decreases with the increasing Tb3+ or Sm3+ concentration. At the same time, the energy transfer efficiency increases from 5.4% and 5.7% to 24.0% and 27.1%, respectively. CIE color coordinates of Ce3+/Tb3+/Sm3+ co-doped CBS glasses shift from cyan to white with increased excitation wavelength. A complex white light emitting is obtained when Ce3+/Tb3+/Sm3+ concentration equals 0.375%/4%/1.5%, respectively.关键词：luminescent glass;high temperature melting method;energy transfer;luminescence modulation127|85|1更新时间：2020-08-12
- 摘要：Using ethylene glycol (EG) and glycerol (GL) as the carbon source and monobasic alcohol (isopropanol(IPA) and ethanol(ET)) as the comparison, the carbon dots(CDs) were synthesized by solvothermal method. CDs were characterized and analyzed by Fourier transform infrared spectra, UV-visible absorption spectra and fluorescence spectra. The effects of different carbon sources on the fluorescent properties and surface functional groups of CDs were discussed, so as to analyze their fluorescence performance. The results show that CDs prepared by using EG or GL as carbon source contain C=C and C=O bonds. The obtained CDs showed a strong emission at the wavelength of 450 nm, with an optimum excitation of 365 nm. The analysis showed that monobasic alcohols lie on the lone pair electrons of C-OH groups to produce fluorescence, indicating monobasic alcohol as a carbon source can not produce carbon dots. The content of hydroxyl has a great impact on the preparation of carbon dots.关键词：carbon dots (CDs);alcohol;hydroxyl;fluorescence performance181|109|0更新时间：2020-08-12
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CVD Synthesis of Doped BNx-graphene Hybrid Nanomaterials: Structure and Photoluminescence Properties
摘要：Three dimensional doped BNx-graphene hybrid nanomaterials were synthesized, where the doped BNx nanorods were synthesized in N2-H2 plasma by CVD, followed the growth of graphene nanoflakes on the surfaces of doped BNx nanorods in CH4 environment by CVD. The characterization results indicate that the synthesized hybrid nanomaterials are composed of C and O co-doped BNx nanorods and graphene nanoflakes. The formation of three dimensional C and O co-doped BNx-graphene hybrid nanomaterials is related to the conversion of hydrocarbon radicals and the stress in the graphene nanoflakes produced due to the deformation of doped BNx nanorods. The photoluminescence(PL) properties at room temperature indicate that ultraviolet and green light emitted from the doped BNx nanorods is quenched by the graphene nanoflakes, which results from the charge transfer and electron scattering occurring in the doped BNx-graphene interfaces.关键词：doped BNx-graphene hybrid nanomaterials;chemical vapor deposition;photoluminescence properties136|79|0更新时间：2020-08-12 - 摘要：CdSe:Nd nanocrystals (CdSe:Nd NCs) were synthesized via organic phase method. The objective of this research was to investigate structure, microstructure, optical properties and possible luminescence mechanism of CdSe:Nd and CdSe:Nd@SiO2. It is confirmed that Nd3+ is successfully incorporated into the crystal lattice of CdSe through XRD, TEM, UV-visible absorption spectroscopy and fluorescence emission. Compared with pure CdSe NCs, CdSe:Nd NCs still have a cubic crystal structure, the lattice constant of CdSe and CdSe:Nd NCs is 0.605 and 0.609 nm, respectively. The lattice of CdSe:Nd constant increases, it may be due to the ionic radius of Nd3+ is larger than Cd2+. When Nd3+ is incorporated into the crystal lattice of CdSe:Nd NCs, which results in dilation of crystal lattice. CdSe:Nd NCs are monodisperse and spherical particles with an average diameter of 2-4 nm. Both absorption spectrum and emission spectrum red-shift, and the quantum yields of the CdSe:Nd NCs also increase, which may be due to the introduction of new impurity levels and the decrease of the band gap. To enhance the stability and functionality of CdSe:Nd NCs, CdSe:Nd NCs were coated with SiO2 (CdSe:Nd@SiO2 spheres) and the core-shell SiO2 -coated CdSe:Nd NCs (CdSe:Nd@SiO2) were prepared via the micro-emulsion method. XRD patterns show that the patterns of CdSe:Nd@SiO2 contain the characteristic peak of CdSe:Nd NCs, which proves that CdSe:Nd has entered in the SiO2 shell successfully. CdSe:Nd NCs are uniform spherical with an average diameter of 100-115 nm, and CdSe:Nd NCs can be clearly seen in the SiO2 shell. The fluorescence emission of CdSe:Nd@SiO2 (581 nm) shows a blue-shift compared with CdSe:Nd NCs(598 nm), possibly because of altered surface properties and reduction of nonradiative transitions.关键词：CdSe:Nd nanocrystals;doped;CdSe:Nd@SiO2 nanospheres;fluorescence properties;core-shell128|60|1更新时间：2020-08-12
- 摘要：GaN thin films were grown on sapphire substrate by MOCVD method. Eu3+ ions were implanted into GaN thin films by ion implantation. After the films were annealed, the crystal quality was improved partly according to X-ray diffraction measurements. The strong red light emission at 623 nm can be observed in the cathodoluminescence spectrum, and is attributed to the internal 4f transition of Eu3+ ions. In addition, the charge transfer state is introduced by ion implantation, results in a luminescence peak at 408 nm. It is found that annealing can help to promote the charge transfer state luminescence and Eu ions luminescence. There is an energy transfer from the yellow peak of GaN matrix to the Eu ions.关键词：gallium nitride;cathodoluminescence;europium;luminescence;energy transfer118|69|1更新时间：2020-08-12
- 摘要：At room temperature, ZnO/Ag/ZnO transparent conductive films were prepared on glass substrate by RF magnetron sputtering of zinc oxide(ZnO) powder and silver(Ag). When the thickness of ZnO was 30 nm, the thickness of Ag was changed to prepare three layers of transparent conductive films, and the influence of the thickness of Ag layer and the ratio between the layers on the photoelectric properties were studied. According to the ZnO/Ag ratio of 30:11, different thickness of three transparent conductive films were prepared, and the effect of multilayer thickness on the photovoltaic properties was researched. The results show that the surface of ZnO/Ag/ZnO with thickness of 8 nm and 11 nm are relatively flat, and have good degree of crystallinity with the maximum transmittance of 90% and 86% in the visible range and the sheet resistance of 6 Ω/□ and 3.20 Ω/□. The photoelectricity is excellent. When ZnO/Ag/ZnO three-layer films are prepared according to the ratio of 30:11, increasing the thickness of ZnO layer on the contrary enhances the light transmittance of Ag layer but decreases the overall optical layer thickness of the three-layer films.关键词：transparent conductive films;RF magnetron sputtering;powder target;coating171|101|2更新时间：2020-08-12
- 摘要：With the development of single emitter diode laser fiber coupling technology, in order to improve the output power of the multi-single emitters diode laser, the curved surface spatial combination, as a special way, was introduced to coupling the multi-single diode laser emitters into the fiber, which can combine the most number of single emitters in same optical fiber for increasing the output power. In simulation, with ZEMAX optical design software, 34 single emitters diode lasers with a center wavelength of 975 nm and 10 W output power are coupled into a fiber with core diameter of 200 μm and NA of 0.22. The simulation results of the maximum output power of 312.03 W and the coupling efficiency of 91.76% were obtained. We assembled a multiple single emitter diode laser based on 17 single emitters and coupled the beam into the optical fiber of which the core diameter is 200 μm and the numerical aperture is 0.22. Under 10.5 A driving current, the output power is 100.5 W and the coupling efficiency to be 68.46%.关键词：single emitter diode laser;curved surface spatial combination;ZEMAX;fiber coupling133|86|1更新时间：2020-08-12
- 摘要：GaN films were grown on Si (111) substrates by metal-organic chemical vapor deposition (MOCVD). The influence of high temperature AlN(HT-AlN) buffer low various growth pressure (6.7-16.6 kPa) on GaN films was studied. It is found that, the surface morphology and structural and optical properties of the GaN epilayer strongly depend on HT-AlN buffer growth pressure. Increase the growth pressure of HT-AlN buffer, the optical and morphology properties of GaN film are both significantly improved, when the growth pressure of HT-AlN buffer layer was at 13.3 kPa, we obtained a crack-free GaN film, the XRD FWHM of (002) and (102) plane of GaN film are 735 and 778 arcsec, respectively. The tensile stress calculated from Raman spectra is 0.437 GPa, and RMS roughness of AFM 5 μm×5 μm scan is 1.57 nm.关键词：HT-AlN buffer;GaN;MOCVD;X-ray diffraction;Raman spectroscopy151|118|0更新时间：2020-08-12
- 摘要：N, N'-di-n-octyl-3,4,9,10-perylene tetracarboxylic diimide(PTCDI-C8) was used as the interfacial layer of the electron transport layer PCBM to reduce the leakage current between PCBM and Al electrode and to improve the electron collecting efficiency of cathode. By adjusting the thickness of PTCDI-C8 film, the interfacial contact and electron transport properties were optimized. Compared with the control devices, the power conversion efficiency (PCE) of the optimal device achieves 8.65% with 20 nm thickness PTCDI-C8 film, with an open circuit voltage (Voc) of 0.92 V, a short circuit current (Jsc) of 15.68 mA/cm2 and a fill factor (FF) of 60%. PTCDI-C8 layer can effectively block the hole transmitting to the cathode. With a higher electron mobility and stability, PTCDI-C8 layer can reduce the environment erosion on the PCBM. In summary, the introduction of PTCDI-C8 film as cathode buffer layer improves the performance and stability of the device.关键词：perovskite solar cells;interface engineering;hole-blocking;charge separation115|58|0更新时间：2020-08-12
- 摘要：The fabrication of the isolation trough is an effective way to realize independence of the array chip unit. In this paper, four kinds of isolation depth and six different chip sizes were fabricated on GaN-based LED arrays using inductively coupled plasma dry etching(ICP) with high etching ratio hybrid-mask SiO2 and photoresist. The effect of different etching sizes and depths on the electrical performance of LED array chip was characterized by electroluminescence(EL) and capacitance tester. The experimental results show that the smaller chip has a higher endured current density and smaller capacitance. With the increase of the etching depth, both the resistance and capacitance decrease, which reduces the RC time constant. The RC bandwidth of the samples with 120 μm Mesa increases from 155 MHz to 176 MHz when the etch depth is from Mesa etch only to completely etch to the sapphire substrate. Reducing the chip size and completely etching to the sapphire substrate can effectively reduce the chip RC time constant. These efforts will facilitate the future design and manufacture of GaN-based LEDs to improve the modulation bandwidth of high-frequency visible light communications.关键词：deep etching isolation;micro-LED chip;capacitance;RC constant159|124|1更新时间：2020-08-12
- 摘要：The dye doped cholesteric liquid crystal(CLC) laser with interdigitated electrodes pattern was designed and the lasing spectra of the device in different voltages were investigated. The bottom glass substrate was patterned with interdigitated ITO electrode using the laser etching method. The width of a single electrode was approximately 2 mm and the distances between neighboring electrodes were approximately 1, 3 and 5 mm, respectively. There were no ITO electrodes on the upper glass substrate. In order to achieve a planar alignment state of CLC, a parallel rubbing treatment was performed on both substrates. A 532 nm Nd:YAG pulsed solid-state laser was used to pump the cell. When the voltage changed from 0 to 100 V, a multi-wavelength lasing was obtained. A tunable output lasing was obtained at the wavelength range of 633.65-621.52 nm(12 nm) and 683.15-664.35 nm(18 nm) where the distance between neighboring electrodes was approximately 1 mm. However, the lasing spectra were scarcely modified if the distances between neighboring electrodes were approximately 3 mm and 5 mm. Under an applied external voltage, the uniform helical alignment of CLC was disturbed and the helical axis was tilted. This cause equivalent helical pitch shrinks and floating. Therefore, the output lasing wavelength can be blue-shifted and multimode lasing was presented. The lasing spectrum was simulated using optical density theory. When the helical pitch is a function of a tilt angle, the output lasing blue-shift increases with tilt angle.关键词：cholesteric liquid crystal laser;interdigitated electrodes pattern;lasing spectrum;voltage130|91|1更新时间：2020-08-12
- 摘要：The optimization of the PLS regression model of wine alcohol content was studied. The near-infrared spectroscopy was used to collect the spectral data of the wine samples and the data were used to establish the quantitative model of alcohol to achieve rapid on-line detection. PLS regression model and FA model were established based on the selected variables, chosen by MC-UVE and GA. The results show that the MC-UVE-GA-FAR model, which yielded R2 of 0.946 and RMSEP of 0.215, is superior to the MV-UVE-GA-PLS model. In comparison of the performance of the full-spectra PLS regression model, the model based on the selected wave numbers is much better, and 6 variables in total are selected, which greatly simplifies the model. The study indicates the MC-UVE, GA and FA can optimize the model.关键词：near-infrared spectroscopy;wine;genetic algorithm;Monte-Carlo uninformative variable elimination;factor analysis156|84|5更新时间：2020-08-12
- 摘要：Two new vinylmethylketone derivative, 4-amino-4-(4-methoxyphenyl) but-3-en-2-one (1b) and 4-amino-4-(1,3-benzodioxol-5-yl) but-3-en-2-one(2b) were synthesized and investigated as a possible fluorescent probe for formaldehyde detection. The linear absorption and fluorescent spectra of 1b and 2b in different formaldehyde concentration were investigated. The results indicate that the compound 1b and 2b have a intricate variation trend existing in UV-Vis absorption spectra and one-photon fluorescence spectra, respectively. In terms of single photon fluorescence, the fluorescence emission peak of compound 1b is located at 384 nm, which is 50 nm red shift compared with UV absorption peak. The fluorescence emission peak of compound 2b consists of two peaks located at 384 nm and 411 nm, respectively. When 15 μmol/L of formaldehyde is added, the fluorescence emission peak of the compound 2b is obviously enhanced and the overlap degree of the two peak is reduced, which can be used to detect the characteristics of formaldehyde. These results show that 4-amino-4-(4-methoxyphenyl) but-3-en-2-one(1b) and 4-amino-4-(1,3-benzodioxol-5-yl) but-3-en-2-one(2b) are able to be as a promising candidate for formaldehyde detection.关键词：formaldehyde detection;fluorescence probe;UV-Vis absorption spectra;one-photon fluorescence spectra125|96|0更新时间：2020-08-12
- 摘要：A novel type of dual-mode optical nanoprobe combining fluorescence and surface enhanced Raman scattering was described. Firstly, the fluorescent nanoparticles doped with coumarin 6(C6) and coated with silica were prepared by a reprecipitation-encapsulation method. Then, PLL molecules were electrostatically absorbed onto the surface of negatively charged NPs. Subsequently, the silver nanoparticles were attached to the surface of PLL shell by the in-situ reduction. Finally, Raman molecules were connected on the silver nanoparticles surface. The fluorescent signal in this probe derives from the fluorescent molecular C6. The silver nanoparticles are used as the enhanced substrate of SERS, and the SERS signal is from Raman molecules. The double-mode analysis technique, combining fluorescence and surface enhanced Raman scattering, possesses high resolution and sensitivity of imaging, and is promising in the biomedical field.关键词：fluorescence;surface enhanced Raman scattering;silver nanoparticle;nanoprobe134|63|0更新时间：2020-08-12
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