最新刊期
卷 32 ， 期 6 ， 2011
- 摘要：The rare earth fluorides nano- and micro-materials as well as controlled morphologies, formation mechanisms and luminescence properties are studied in this paper. A facile, general, template-free and environmentally friendly hydrothermal methodology has been developed to prepare the whole rare earth fluorides nano- and microcrystals. Organic additive trisodium citrate plays double roles of coordination ligand and shape modifier in determining the morphologies of the final products. Through the precise tuning several critical parameters including F- sources (NaF, NH4F, NaBF4), pH value in the initial solution and the choice of organic additives, the whole rare earth fluorides with various compositions, crystal structures, uniform sizes and morphologies have been obtained easily, including REF3(RE=La~Lu) as well as cubic and hexagonal phase NaREF4(RE=Y, Yb, Lu). More importantly, for the first time, the controllable synthesis of ytterbium (or lutetium) fluoride compounds with diverse crystal phase and morphologies have been reported. The possible formation mechanisms for products with various architectures have been presented systematically. The photoluminescence properties of Eu3+, Tb3+-doped DC and Yb3+/Er3+, Yb3+/Tm3+ -codoped UC NaREF4 or REF3 have also been investigated in detail.128|221|6更新时间：2020-08-12
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Synthesis of Nano-sized Sr2SiO4 ∶ Eu3+ Phosphor by Combustion Method and Its Luminescence Properties
摘要：Nano-sized Sr2SiO4 ∶ Eu3+ phosphors were successfully synthesized by a rapid synthetic route using the combustion method. Through the chemical reaction of Sr(NO3)2, Eu(NO3)3, and fumed silica, pure-phase of nano-size α-Sr2SiO4 ∶ Eu3+ can be obtained by sintering under 800 ℃ for 3 min. The crystallization and morphology of the as-synthesized Sr2SiO4 ∶ Eu3+ phosphors were investigated using XRD and scanning electron microscopy. The Sr2SiO4 ∶ Eu3+ particle size is in a range of 80~100 nm. Furthermore, luminescence properties of the nano-size Sr2SiO4 ∶ Eu3+ phosphors, including photoluminescence, high-resolution emission spectra, site-selective excitation and emission spectra and excited-state decay curves are also systemically discussed in this paper and compared with that of Sr2SiO4 ∶ Eu3+ prepared by the conventional high-temperature solid-state reaction method. Under UV light excitation, this phosphor shows intense red light. Due to the presence of the surface states that the Eu3+ are located, the local environment of the Eu3+ sites in nano-sized Sr2SiO4 ∶ Eu3+ phosphor are more complicated compared with that of the bulk material, which leads to the decreased excited lifetime values. Furthermore, the luminescence decay curves of Eu3+ changing from single-exponential to double-exponential due the presence of the surface states.关键词：luminescence;combustion method;Sr2SiO4;nano materials171|108|2更新时间：2020-08-12 - 摘要：The opal photonic crystals were fabricated with silica colloidal particles. These opal photonic crystal samples were annealed at 150,300,450 ℃ separately. For the photonic crystals annealed at 450 ℃, the central wavelength of photonic band gap(PBG) was measured at 572.5 nm, which was greatly different from the calculated result at 605 nm. In addition, the samples showed a blue shift for 22.5 nm and a reduction of the photonic band gap width upon increasing the annealing temperature. The shrink and deformation of silica colloidal particles were observed by SEM. The influence mechanism of the deformation was analyzed quantitatively, and the theoretical model was amended. The central wavelength of PBG re-calculated with the amended dodecahedron model was 558 nm, which fit the measured result much better than that calculated with the old sphere model. The new dodecahedron model provides a way to analyze the optical properties of the deformed opal PCs in theory, and shall be of significant value on the fabrication and application of photonic crystals devices.关键词：photonic crystals;self-assembly;photonic band gap111|1088|1更新时间：2020-08-12
- 摘要：Mn2+ doped Zn2SiO4 phosphors had been prepared by hydrothermal method in stainless-steel autoclaves using the mixed solvent of ethidene diamine and H2O. The crystalline structures and the morphologies of the samples were studied with X-ray diffraction apparatus (XRD) and scanning electron microscopy (SEM), and the reaction process was detected with the results of XRD and SEM. The optic properties were measured with UV-Vis Absorption Spectrometer and Fluorescence spectrometer. Results show that Zn2SiO4 crystal can be obtained by hydrothermal method at 200 ℃ for 6 d, and the product is a short rod with the width about 0.25 μm and the length about 1 μm. Absorption spectra show an absorption edge at about 380 nm and two absorption bands at about 250 nm and 220 nm. Mn2+ doped Zn2SiO4 has a luminescence band with the peak wavelength at about 522 nm under 253 nm excitation without further thermal treatment.关键词：Mn2+ doped Zn2SiO4;photoluminescence;hydrothermal technology120|93|1更新时间：2020-08-12
- 摘要：The 20% concentrated Eu3+-doped red-emitting phosphor, nano-sized La6WO12 ∶ Eu3+ was prepared by the Pechini method. X-ray diffraction (XRD), thermogravimetric analysis (TG-DTG), scanning electron microscopy (SEM), fluorescence spectrum, diffuse reflectance spectrum and decay curves were used to characterize the resulting samples. The phosphor can be efficiently excited by near UV light and exhibits an intense red luminescence corresponding to the electric dipole transition 5D0→7F2 at 615 nm. When the phosphor was mixed into poly (vinyl alcohol) aqueous solution, the fluorescent nanofibers could be prepared by electrospinning process. It was suggested that the La6WO12 ∶ Eu3+ phosphor would be a promising red component for solid-state lighting devices based on InGaN or GaN white-light-emitting diodes.关键词：Pechini method;Eu3+;electrospinning;nano-flourescent material87|102|0更新时间：2020-08-12
- 摘要：A series of new FED (Field Emission Display) green phosphors of MSi2N2O2 ∶ Eu2+ (M=Sr, Ba) are synthesized by solid state reaction, and their luminescence properties under the excitation of different voltage and current density are studied. Under the excitation of electron beams, SrSi2N2O2 ∶ Eu2+ emits yellow green light with the peak at 541 nm, and BaSi2N2O2 ∶ Eu2+ shows a blue-green emission dominates at 492 nm. The current saturation character of BaSi2N2O2 ∶ Eu2+ is better than that of SrSi2N2O2 ∶ Eu2+. While, under the excitation of the same current density, the luminescence intensity of SrSi2N2O2 ∶ Eu2+ is much higher than that of BaSi2N2O2 ∶ Eu2+. So, SrSi2N2O2 ∶ Eu2+ is more suitable for FED application.关键词：FED;phosphor;MSi2N2O2 ∶ Eu2+;luminescence properties102|53|1更新时间：2020-08-12
- 摘要：Er3+ /Tm3+-codoped Ga5Ge20Sb10S65 glasses were prepared by traditional melt-quenching method. Fluorescence spectra were investigated under 980 nm and 800 nm LD excitation. Combined with their absorption spectra, the Judd-Ofelt intensity parameters Ωi (i=2,4,6), spontaneous transition probabilities A and rediative lifetomes τ for Er3+ ion were calculated by Judd-Ofelt theory. Due to the energy transfer from 4I13/2 of Er3+ to 3F4 of Tm3+ , the addition of Tm3+ significantly reduced the lifetime of the 4I13/2 level of Er3+ , that in turn increase the possibility of population inversion between the 4I11/2 and 4I13/2 levels of Er3+. It is learned that the intensity of 2.76 μm mid-infrared fluorescence firstly increased, and then dropped in the Er3+ /Tm3+-doped Ga5Ge20Sb10S65 glasses with the increase of Tm3+ ion concentration.关键词：chalcogenide glass glasses;Er3+/Tm3+-codoped;energy transfer111|35|1更新时间：2020-08-12
- 摘要：Alkali-alkaline earth borate K2O · CaO · 4B2O3 · 12H2O ∶ Nd3+ was investigated by easy industrialization and pollution-free water solution method. K2B4O7,CaCl2,Nd2O3 were used as starting materials.The production was characterized by chemical analysis, FT-IR spectra, X-ray powder diffraction and SEM, fluorescence spectrum, etc. The results show that K2O · CaO · 4B2O3 · 12H2O ∶ Nd3+ have fine shape and tidy surface. The matrix material had upconversion luminescence property, and the intensity of K2O · CaO · 4B2O3 · 12H2O ∶ Nd3+ was weaker than matrix, both of them appeared orange emission under 828 nm excitation.关键词：K2O ·CaO ·4B2O3 ·12H2O ∶ Nd3+;water solution method;characteristics101|22|5更新时间：2020-08-12
- 摘要：Top-emitting white organic light-emitting diodes (TWOLEDs) have attracted intensive attention due to their great potential for high-resolution full color active matrix display and lighting applications. We have investigated optical and electrical characteristics of the TWOLED combining electroluminescence (EL) of blue material (ADN) with top color conversion layer (CCL) based on non-doped red material (NPAMLI). The TWOLED, with structure of Glass substrate/Al/Cs2CO3/Alq3/ADN/NPB/MoO3/Au/Alq3/NPAMLI, was fabricated by vacuum thermal evaporation. The 10 nm thick Au was used as top semitransparent anode, the 40 nm thick Alq3 was used as a capping layer to improve the light out-coupling, and the non-doped red material NPAMLI was used as the CCL. The NPAMLI CCL showed strong absorption from 450 nm to 550 nm, which matched well with the emission of the ADN. The EL spectra of the TWOLED additionally contained a red component from NPAMLI, which absorbed a part of the blue EL of the ADN, and converted this to its red fluorescence. Therefore, the TWOLED yielded a white light emission resulting from final mixture of color-converted red light and unabsorbed blue light. The TWOLED with a peak current (power) efficiency of 1.25 cd/A (0.71 lm/W), CIE coordinates of (0.330, 0.292), and a color rendering index of around 87.5, has been obtained.关键词：top-emitting;white organic light-emitting diodes;color conversion layer94|144|0更新时间：2020-08-12
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Highly Efficient Blue Phosphorescent OLEDs Based on 1,3,5-tri(9H-carbazol-9-yl)benzene Host Material
摘要：Hightly efficient blue phosphorescent organic light emitting diodes(OLEDs) based on a host material 1,3,5-tri(9H-carbazol-9-yl)benzene (TCzP) doped (iridium(Ⅲ) picolinate) (FIrpic) were fabricated, and a double-emitting layer device was also manufactured. The maximum brightness of 11 957 cd/m2, peak current efficiency of 18.8 cd/A with Commission Internationale de L'Eclairage (CIE) coordinates of (0.17, 0.37) were obtained. The emission peak wavelength of 472 nm with its shoulder peaking at 496 nm were observed. Even at high brightness of 1 000 cd/m2, the current efficiency remains 13.5 cd/A. The experimental results indicate that high triplet energy and hole mobility for a host material are very important to achieve highly efficient blue phosphorescent device.关键词：physical optics;phosphorescent organic light emitting diodes;double emitting-layer;TCzP120|280|1更新时间：2020-08-12 - 摘要：The doping devices with the structure of ITO/NPB/Zn(4-TfmBTZ)2 ∶ NPB/LiF/Al are fabricated, where the NPB male fraction in Zn (4-TfmBTZ)2 layer is 0, 5%, 10%, 20%, respectively. The results show that the mole fraction of NPB in Zn(4-TfmBTZ)2 layer has important effect on the device performance, which contains not only efficiency but also chromaticity and color rendering index. As the NPB mole fraction in Zn(4-TfmBTZ)2 layer in creases gradually from 0 to 10%, the electroplex emission enhances gradually, the device efficiency increases firstly and hten reduces, and the light color becomes grodually from blue white, white to yellow white at the same voltage. When the mole fraction of NPB in Zn(4-TfmBTZ)2 layer is 5%, the device shows the best performance with the color coordinate region of (0.28~0.32,0.33~0.35) and the color rendering index of 83.3~91.2 at voltage of 6~9 V. The maximum efficiency of this device is 0.87 cd/A.关键词：bis[2-(4-trifluoromethyl-2-hydroxyphenyl-benzothiazolate)]zinc;electroplex;white light;doping103|21|1更新时间：2020-08-12
- 摘要：High-brightness tapered laser diode at 850 nm was fabricated based on the AlGaInAs/A1GaAs chip with graded-index waveguide separate confinement hetero-structure. The tapered laser has better performance than the broad laser under the same condition. The lateral divergence angles of the tapered laser and the broad laser were 4° and 6° at the output power of 1 W, while the beam propagation factor M2 were 2.8 and 9.2, respectively. The slope efficiency of the tapered laser had a high value of 0.58 W/A and the conversion efficiency reached 30% in the output power 1.40 W under the injection current of 3 A. The facts indicated the tape-red laser would be an ideal choice for high brightness high power laser diodes.关键词：850 nm;tapered laser diode;high-brightness;the beam propagation factor108|121|4更新时间：2020-08-12
- 摘要：The processing of the wet etching have been studied with experiments in oxidation confinement high-power vertical-cavity surface-emitting lasers (VCSEL) in order to improve opto-electric characteristics of high-power VCSEL. In the experiments we use the H3PO4 liquid as etching liquid in stead of H2SO4 liquid. The relation between the etching shape change of the epitaxial wafer with etching liquid consistency by scanning electron microscope (SEM), we eliminated the "dovetail" structure that conventionally happened on the lateral side of the etched wall of high-power VCSEL oxidation layer; By chaging the etching liquid content and the etching condition temperature, we have studied the law of the wet etching rate. At last,we have obtained the best temperature condition and etching liquid concentration of wet etching through the experiment.关键词：laser technique;VCSEL;wet etching;etching rate113|151|0更新时间：2020-08-12
- 摘要：The green LED with vertical structure was fabricated by transferring the epilayers of GaN-based LED grown on Si (111) substrate to a new Si substrate. Four groups of LED with chip size of 200 μm×200 μm were fabricated, labeled as sample A, B, C and D, respectively. Sample A was uncoated. Top surface of sample B, sidewall of sample C and both top surface and sidewall of sample D were coated with SiON passivation layer under the same experimental condition. Electrical and optical properties were investigated after 168 hours accelerated aging under 60 mA DC current at room temperature. The results show that the sidewall-SiON layer could decrease the generation of non-recombination centers in the active layer. Thus it could reduce leakage currents and the luminous decay. Comparing to the top-surface SiON, the sidewall SiON played a decisive role in improving the reliability of the LED .关键词：SiON;Si substrate;GaN;luminous decay;LED132|96|2更新时间：2020-08-12
- 摘要：Amorphous SiO2 thin films with about 500 nm in thickness were thermally grown on single crystalline silicon. These SiO2/Si samples were irradiated at room temperature (RT) by 853 MeV Pb-ions to 5×1011, 1×1012, 2×1012 or 5×1012 ions/cm2, and by 308 MeV Xe-ions to 1×1012 or 5×1012 ions/cm2, respectively. The variation of photoluminescence (PL) properties of these samples was investigated at RT using a fluorescent spectroscopy. The obtained results showed that Pb/Xe-ion irradiation led to significant changes of the PL properties and the variation of the PL properties depend strongly on the fluence of the Pb-ion irradiations and electronic energy loss of ions. For examples, huge PL peaks located at about 473 nm and 645 nm can be seen in PL spectra of 5×1012 Pb-ions/cm2 irradiated sample. Furthermore, with increasing of Pb-ion irradiation dose the intensity of these PL peaks increased. This implied that some micro-structure modifications like defects were induced by swift heavy ion irradiations, such as non-bridging oxygen defects (≡SiO·), oxygen-vacancies defects (≡Si—Si) and Si—O related defects (O—Si—O). Special light emitters will be achieved by using proper ion irradiation conditions, and it will be very useful for the synthesis of new type of SiO2-based light-emission materials.关键词：photoluminescence;swift heavy ion irradiation;defect114|58|1更新时间：2020-08-12
- 摘要：In0.82Ga0.18As layers were grown on semi-insulating Fe-doped InP (100) substrates by low pressure metalorganic chemical vapor deposition (LP-MOCVD). The growth was performed using TMIn, TMGa, and AsH3 as growth precursors of In, Ga, and As, respectively, in a horizontal reactor. The substrate on a graphite susceptor was heated by inductively coupling radio frequency power, the growth temperature was detected by a thermocouple, and the reactor pressure was kept at 1×104 Pa. Thickness of In0.82Ga0.18As layer for all samples was kept to be 300 nm. In our experiments, the growth temperature of In0.82Ga0.18As layers was 390, 410, 430, 450, 470, 530 ℃, respectively. Because the strain caused by the lattice mismatch between In0.82-Ga0.18As layer and InP substrate was varied from the growth temperature, the surface of In0.82Ga0.18As layer was different. It was analyzed that the growth temperature of In0.82Ga0.18As layer influenced on the surface morphology, crystalline quality and the electrical property of the In0.82Ga0.18As layer. The surface morphology of In0.82Ga0.18As layer was studied by the scanning electron microscopy (SEM). The components and crystalline quality of In0.82Ga0.18As layer were characterized by X-ray diffraction (XRD). The electrical property of In0.82Ga0.18As layer was measured using the Hall Effect. This work shows a useful way how to design for the optimum buffer in growthing highly mismatched epitaxy layers.关键词：In0.82Ga0.18As;MOCVD;buffer108|78|0更新时间：2020-08-12
- 摘要：The optical properties of porphyrins have been extensively investigated in the fields of labels, catalysts and sensors, which are attributed to the absorbance in the near ultraviolet and visible region and emission in the red light region. In general, porphyrins present weak luminescence in aqueous media. Especially, the emission of metal phorphyrin shows much weaker. Therefore, it is a challenging task to enhance the emission of the metal complex in aqueous system. In this paper, the optical properties of metalloporphyrin complex, silver (Ⅱ) tetra-phenyl porphyrin, (TPP-Ag), intercalated into an inorganic lamellar framework (dodecyltrimethylammomium zirconium phosphate, DTZrP) was studied. It was attempted to optimize the optical property resorting to the special microenvironment provided by DTZrP. The DTZrP lamellar framework was prepared by lyophilization method, and the result of X-ray powder diffraction demonstrates that the interval of the lamellar framework is about 3.00 nm. The metalloporphyrin TPP-Ag was synthesized according to previous procedure and characterized with FTIR, UV-visible, and elementary analysis. By means of intercalation chemistry, the TPP-Ag chromophore was assembled into DTZrP successfully. The optical behavior of the chromophore takes on evident change. The Soret absorption peak is red-shifted from 421 nm in the aqueous solution to 429 nm in the suspension. Most of all, the fluorescence property of TPP-Ag assembled into lamellar framework is improved dramatically compared to the chromophore in the aqueous solution. The fluorescence intensity is enhanced by nearly 10-fold. It is concluded that the lamellar framework DTZrP provides appropriate setting which can improve effectively the optical behavior. The optimized fluorescence property is in favor of the chromophore as fluorescence probe in the body of organism.关键词：metalloporphyrin;modified zirconium phosphate;assembly;optical property104|76|3更新时间：2020-08-12
- 摘要：The fluorescence properties of three thulium bisphthalovanine compounds were studied using the steady-state fluorescence and time-resolved fluorescence spectra. Meanwhile, the effect of the concentration, excitation wavelength and substituents on the fluorescence properties was discussed. A strong fluorescence emission at about 700 nm was found in the thulium bisphthalocyanine chloroform solution. The π-electron delocalizability of phthalocyanine macrocyle was strengthened, and the energy gap between π and π* molecular orbital decreased with the alkoxyl substitutent —OC8H17 being added. Meanwhile, there formed the p-π conjugation system resulting from the interaction between non-bonding electron of —OC8H17 and π electron of phthalocyanine rings, which reduced the energy gap between π and π* molecular orbits further, and made both the emission peak red shift and the emission intensity change. The fluorescence at about 700 nm exhibited two lifetimes, originated from the monomer and aggregates of phthalocyanines respectively. With the concentration decreasing, the components of monomer increased gradually.关键词：bisphthalocyanine;fluorescence;lifetime;substitutent125|128|0更新时间：2020-08-12
- 摘要：In Tris-HCl buffer medium of pH 7.40, the binding reaction between cefotaxime sodium (CTX) and chloramphenicol (CHL) with bovine serum albumin (BSA) at different temperatures was studied by fluorescence spectroscopy. The results show that the values of binding constants decrease with the increasing temperature,the quenching mechanism of the combination for BSA and drugs is a static procedure. In addition, the competitive experiments suggest that the primary binding site for both CTX and CHL are located at site Ⅰ in sub-domain ⅡA of BSA. The values of Hill's coefficients are approximately equal to 1 in the binary systems, which indicate no cooperativeness in the drug's binding with BSA. The fluorescence would quench to a larger degree when CTX (or CHL) is added to the system of BSA-CHL (or BSA-CTX). Binding constants of one drug with BSA decrease when the other drug is added. Hill's coefficients of the ternary systems are less than 1. It showed that the negative cooperativity is found when CTX and CHL bound to BSA simultaneously. Thermodynamic parameters indicate that the electrostatic interaction playes a major role in the binding of drugs with BSA.关键词：fluorescence spectroscopy;cefotaxime sodium;chloramphenicol;bovine serum albumin102|177|6更新时间：2020-08-12
- 摘要：Due to the unique and tunable optical properties, gold nanorods have potential and important applications in the biomedical field. In this paper, gold nanorods with the aspect ratio 8 were prepared, an outstanding fluorescence feature of the gold nanorods excited at 480 nm was observed in terms of a strong fluorescence emission at 707 nm and a relatively weak fluorescence at 560 nm. Based on their fluorescence properties, HepG2 cells were labeled by this type of gold nanorods, and were studied by using laser scanning confocal microscope. Green and red fluorescence images of gold nanorods were collected under the excitation of 488 nm. Furthermore, high-resolution atomic force microscopy was used to obtain the morphology and mechanical properties changes of the HepGz cells.关键词：gold nanorod;cellular fluorescence imaging;atomic force microscopy;laser scanning confocal microscope;hepatocellular carcinoma cells100|159|2更新时间：2020-08-12
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