Electrochemical polymerization and characterization of polypyrrole nanowires and nanotubules

Polypyrrole nanostructure arrays, including simultaneously large quantities of nanowires and small quantities of partially filled nanotubules have been electrochemically synthesized in home-made etched ion-track polycarbonate (PC) templates. Diameter of the prepared nanostructures varies from 45 to 320 nm with their lengths up to 30 microns. Morphological studies of these nanostructures were performed by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and Raman spectroscopy. While optical absorption properties were studied by ultraviolet-visible-near infrared spectrophotometry (UV-vis-NIR). It has been observed that the absorption maximum of polypyrrole shifts to the longer wavelength side as the diameter of these nanostructures (nanowires and nanotubules) increases. (C) 2010 Elsevier B.V. All rights reserved.

LaGaO3 : A (A=Sm3+ and/or Tb3+) as promising phosphors for field emission displays

LaGaO3:Sm3+, LaGaO3:Tb3+ and LaGaO3: Sm3+, Tb3+ phosphors were prepared through a Pechini-type sol-gel process. X-Ray diffraction, field emission scanning electron microscopy, photoluminescence (PL), and cathodoluminescence (CL) spectroscopy were utilized to characterize the synthesized phosphors. Under excitation with ultraviolet light (250-254 nm), the LaGaO3: Sm3+, LaGaO3: Tb3+ and LaGaO3: Sm3+, Tb3+ phosphors mainly show the characteristic broadband emission (from 300 to 600 nm with a maximum around 430 nm) of the LaGaO3 host lattice, accompanied by the weak emission of Sm3+ ((4)G(5/2) -> H-6(5/2), H-6(7/2), H-6(9/2) transitions) and/or Tb3+ (D-5(3,4) -> F-7(6,5,4,3) transitions). However, under excitation by low-voltage electron beams (1-3 kV), the LaGaO3: Sm3+, LaGaO3: Tb3+ and LaGaO3: Sm3+, Tb3+ phosphors exhibit exclusively the characteristic emissions of Sm3+ and/or Tb3+ with yellow (Sm3+), blue (Tb3+, with low concentrations) and white (Sm3+ + Tb3+) colors, respectively.

Tm3+ and/or Dy3+ doped LaOCl nanocrystalline phosphors for field emission displays

Blue, yellow and white light emissive LaOCl:Tm3+, LaOCl:Dy3+ and LaOCl: Tm3+, Dy3+ nanocrystalline phosphors were synthesized through the Pechini-type sol-gel process. X-Ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL) and cathodoluminescence (CL) spectra were used to characterize the samples. Under UV radiation (229 nm) and low-voltage electron beam (0.5-5 kV) excitation, the Tm3+-doped LaOCl phosphor shows a very strong blue emission corresponding to the characteristic transitions of Tm3+ (D-1(2), (1)G(4) -> F-3(4), H-3(6)) with the strongest emission at 458 nm. The cathodoluminescent color of LaOCl:Tm3+ is blue to the naked eye with CIE coordinates of x = 0.1492, y = 0.0684. This phosphor has better CIE coordinates and higher emission intensity than the commercial product Y2SiO5:Ce3+.

Host-sensitized luminescence of Dy3+, Pr3+, Tb3+ in polycrystalline SrIn2O4 for field emission displays

SrIn2O4:Dy3+/Pr3+/Tb3+ white/red/green phosphors were prepared by the Pechini sol-gel process. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), diffuse reflectance, photoluminescence, cathodoluminescence spectra, and lifetimes were utilized to characterize the samples. XRD reveal that the samples begin to crystallize at 800 degrees C and pure SrIn2O4 phase can be obtained at 900 degrees C. FE-SEM images indicate that the SrIn2O4:Dy3+, SrIn2O4:Pr3+, and SrIn2O4:Tb3+ samples consist of fine and spherical grains with size around 200-400 nm. Under the excitation of ultraviolet light and low-voltage electron beams (1 - 5 kV), the SrIn2O4:Dy3+, SrIn2O4: Pr3+, and SrIn2O4: Tb3+ phosphors show the characteristic emissions of Dy3+ (F-4(9/2) - H-6(15/2) at 492 nm and 4F(9/2) - 6H(13/2) at 581 nm, near white), Pr3+ (P-3(0) - H-3(4) at 493 nm, D-1(2) - H-3(4) at 606 nm, and P-3(0) - H-3(6) at 617 nm, red) and Tb3+ (D-5(4) - F-7(6,5,4,3) transitions dominated by D-5(4) - F-7(5) at 544 nm, green), respectively. All of the luminescence resulted from an efficient energy transfer from the SrIn2O4 host lattice to the doped Dy3+, Pr3+, and Tb3+ ions, and the luminescence mechanisms have been proposed.

Bifunctional magnetic-optical nanocomposites: Grafting lanthanide complex onto core-shell magnetic silica nanoarchitecture

Anew class of bifunctional architecture combining the useful functions of superparamagnetism and terbium complex luminescence into one material has been prepared via two main steps by a modified Stober method and the layer-by-layer (LbL) assembly technique. The obtained bifunctional nanocomposites exhibit superparamagnetic behavior, high fluorescence intensity, and color purity. The architecture has been characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), UV-vis absorption and emission spectroscopy, X-ray diffraction, and superconducting quantum interference device (SQUID) magnetometry.

Sol-gel growth of Gd2MoO6 : Eu3+ nanocrystalline layers on SiO2 spheres (SiO2@Gd2MoO6 : Eu3+) and their luminescent properties

SiO2@Gd2MoO6:EU3+ core-shell phosphors were prepared by the sol-gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDS), transmission electron microscopy ITEM), photoluminescence (PL) spectra as well as kinetic decays were used to characterize the resulting SiO2@Gd2MoO6:Eu3+ core-shell phosphors. The XRD results demonstrate that the Gd2MoO6:Eu3+ layers on the SiO2 spheres begin to crystallize after annealing at 600 degrees C and the crystallinity increases with raising the annealing temperature. The obtained core-shell phosphors have a near perfect spherical shape with narrow size distribution (average size ca. 600 nm), are not agglomerated, and have a smooth surface. The thickness of the Gd2MoO6:Eu3+ shells on the SiO2 cores could be easily tailored by varying the number of deposition cycles (50 nm for four deposition cycles). The Eu3+ shows a strong PL luminescence (dominated by D-5(0)-F-7(2) red emission at 613 nm) under the excitation of 307 nm UV light.

Research on laser welding of cast Ni-based superalloy K418 turbo disk and alloy steel 42CrMo shaft

Exploratory experiments of laser welding cast Ni-based superalloy K418 turbo disk and alloy steel 42CrMo shaft were conducted. Microstructure of the welded seam was characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectrometer (EDS). Mechanical properties of the welded seam were evaluated by microhardness and tensile strength testing. The corresponding mechanisms were discussed in detail. Results showed that the laser-welded seam had non-equilibrium solidified microstructures consisting of FeCr0.29Ni0.16C0.06 austenite solid solution dendrites as the dominant and some fine and dispersed Ni3Al gamma' phase and Laves particles as well as little amount of MC short stick or particle-like carbides distributed in the interdendritic regions. The average microhardness of the welded seam was relatively uniform and lower than that of the base metal due to partial dissolution and suppression of the strengthening phase gamma' to some extent. About 88.5% tensile strength of the base metal was achieved in the welded joint because of a non-full penetration welding and the fracture mechanism was a mixture of ductility and brittleness. The existence of some Laves particles in the welded seam also facilitated the initiation and propagation of the microcracks and microvoids and hence, the detrimental effects of the tensile strength of the welded joint. The present results stimulate further investigation on this field. (c) 2006 Elsevier B.V. All rights reserved.

利用受激发射损耗（STED）显微术突破远场衍射极限

远场光学显微镜受衍射极限分辩率的限制，而近场光学显微镜由于缺乏层析能力，则无法实现超分辨的三维成像，研究了既可突破远场光学显微术的衍射极限分辨率又可实现三维成像的成像技术——受激发射损耗（STED），综述了STED的分辨率与STED光的光强，延迟时间、光斑空间分布等主要参数的关系，以及该技术的最新进展和应用前景。

Read-only memory disk with AgOx and AgInSbTe superresolution mask layer

Two novel read-only memory (ROM) disks, one with an AgOx mask layer and the other with an AgInSbTe mask layer, are proposed and studied. The AgOx and the AgInSbTe films sputtered on the premastered substrates with pit depths of 50 nm and pit lengths (space) of 380 nm are studied by atomic force microscopy. Disk readout measurement is carried out using a dynamic setup with a laser wavelength of 632.8 nm and an object lens numerical aperture (NA) of 0.40. Results show that the superresolution effect happens only at a suitable oxygen flow ratio for the AgOx ROM disk. The best superresolution readout effect is achieved at an oxygen flow ratio of 0.5 with the smoothest film surface. Compared with the AgOx ROM disk, the AgInSbTe ROM disk has a much smoother film surface and better superresolution effect. A carrier-to-noise ratio (CNR) of above 40 dB can be obtained at an appropriate readout power and readout velocity. The readout CNR of both the AgOx and AgInSbTe ROM disks have a nonlinear dependence on the readout power. The superresolution readout mechanisms for these ROM disks are analyzed and compared as well. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Optical transmission larger than 1 (T > 1) through ZnS-SiO2/AgOx/ZnS-SiO2 sandwiched thin films

Optical transmission through flat media should be smaller than 1. However, we have observed optical transmission up to T=1.18. The samples were ZnS-SiO2/AgOx/ZnS-SiO2 sandwiched thin films on glass substrate. The supertransmission could only be observed in the near field. We attribute the supertransmission to the lateral propagation relayed by the laser activated and decomposed Ag nanoparticles. (c) 2006 American Institute of Physics.

Rigorous transmittance analysis of a sub-wavelength Sb thin film lens

We quantitatively analysed the factors contributing to the optical transmission enhancement of a sub-wavelength Sb thin film lens, using the finite-difference time-domain (FDTD) method. The results show that the transmission enhancement of the dielectric with a Gaussian distributed refractive index loaded in a sub-wavelength circular hole is not only due to the high refractive index dielectric, but also due to the specific distributions of refractive index. It is the first study about the effects of the refractive index distribution on the transmission of a sub-wavelength aperture. This kind of lens has practical applications in the very small aperture lasers and for near-field optical storage and lithography.

Read-only memory disk with AgOx and AgInSbTe superresolution mask layer

Two novel read-only memory (ROM) disks, one with an AgOx mask layer and the other with an AgInSbTe mask layer, are proposed and studied. The AgOx and the AgInSbTe films sputtered on the premastered substrates with pit depths of 50 nm and pit lengths (space) of 380 nm are studied by atomic force microscopy. Disk readout measurement is carried out using a dynamic setup with a laser wavelength of 632.8 nm and an object lens numerical aperture (NA) of 0.40. Results show that the superresolution effect happens only at a suitable oxygen flow ratio for the AgOx ROM disk. The best superresolution readout effect is achieved at an oxygen flow ratio of 0.5 with the smoothest film surface. Compared with the AgOx ROM disk, the AgInSbTe ROM disk has a much smoother film surface and better superresolution effect. A carrier-to-noise ratio (CNR) of above 40 dB can be obtained at an appropriate readout power and readout velocity. The readout CNR of both the AgOx and AgInSbTe ROM disks have a nonlinear dependence on the readout power. The superresolution readout mechanisms for these ROM disks are analyzed and compared as well. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

2-氨基-6-乙氧基苯并噻唑类偶氮染料及其金属鏊合物的合成及光学热学性能研究

合成了2-（2-氨基-6-乙氧基苯并噻唑基偶氮）-5-（N,N-二乙基氨基）三氟甲基磺酰苯胺偶氮染料（EBTDATFS）及其与乙酸镍、乙酸钴、乙酸铜、乙酸锌等金属盐鏊合的金属鏊合物。通过红外光谱、紫外-可见吸收光谱和MALDI质谱等对染料及其金属鏊合物进行了结构表征;使用旋涂方法在K9玻璃和抛光的单晶硅基片上制备薄膜;研究了镍金属鏊合物的热学性能;使用椭偏仪研究了Ni和Zn鏊合物的光学常数。结果表明：4种金属鏊合物薄膜最大吸收光谱为621-629nm,且长波边吸收峰陡峭;TGA-DSC测试结果表明镍金属鏊

静动结合的化学腐蚀法制备近场光学探针的理论分析

理论上分析了静动结合的化学腐蚀法制备探针的具体机理及过程。在静态腐蚀的过程中, 利用流体力学Young-Laplace方程的一级近似解获得了光纤插入到HF酸中形成的新月形高度。在动态腐蚀过程中, 详细分析了当静态腐蚀时间和动态腐蚀时间分别取不同值时, 光纤移动速度对光纤探针结构的影响。利用此法可制备出尖端锐利、大锥角或多锥体等各种结构的光纤探针。这为实验上制备出性能优良的探针, 为拓宽扫描近场光学显微镜的应用范围奠定基础。将上述理论分析的结果与本文实验中所得初步结果进行了比较, 所得结果一致。

Optical and surface properties of hybrid TiO2/ormosil planar waveguide prepared by the sol-gel process

Two kinds of silanes, 3-glycidoxypropyltrimethoxysilane (GLYMO) and 3-trimethoxysililpropylmethacrylate (TMSPM), were used to prepare ormosil waveguide films by the sol-gel method. Thirty percent Ti(OBu)(4) and 70% silane were contained in the precursor sets. The properties of films were measured by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV/VIS/NIR spectrophotometer (UV-vis), atomic force microscopy (AFM), m-line and scattering-detection method. The films from GLYMO and TMSPM precursors exhibit similar thickness (2.58 mu m for GLYMO, 2.51 mu m for TMSPM) and refractive index (1.5438 for GLYMO, 1.5392 for TMSPM, lambda=632.8 nm), but the film from TMSPM precursor has higher propagation loss (1.024 dB/cm, lambda=632.8 nm) than the film prepared from GLYMO (0.569 dB/cm, lambda=632.8 nm). Furthermore, the film prepared from TMSPM is easy to be opaque and cracks during coating whereas the same phenomenon was not found for the film prepared with GLYMO. It is confirmed that GLYMO is a better precursor than TMSPM for waveguide film preparation. (C) 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved.