Effect of PbO on precipitation of laser-induced gold nanoparticles inside silicate glasses

We report on three-dimensional precipitation of Au nanoparticles in gold ions-doped silicate glasses by a femtosecond laser irradiation and further annealing. Experimental results show that PbO addition plays the double roles of inhibiting hole-trapped centers generation and promoting formation and growth of gold nanoparticles. Additionally, glass containing PbO shows an increased non-linear absorption after femtosecond laser irradiation and annealing. The observed phenomena are significant for applications such as fabrications of three-dimensional multi-colored images inside transparent materials and three-dimensional optical memory, and integrated micro-optical switches. (c) 2007 Elsevier B.V. All rights reserved.

熔制条件对铋酸盐玻璃性质的影响

采用传统的玻璃熔融法制备了组成为60Bi2O3-20B2O3-15SiO2-5La2O3(mol%)的铋酸盐玻璃， 系统研究了不同工艺过程对玻璃性能的影响. 分析了样品ICP的成分，扫描电镜，X-射线衍射谱， 差热分析和紫外-可见-近红外透过光谱测试. 结果表明：使用刚玉坩埚能提高玻璃的抗析晶稳定性 和透过率，陶瓷坩埚和白金坩埚均受到严重腐蚀，玻璃组分也随之发生很大变化. 当熔制温度从1 100 ℃变化到1 300 ℃时，玻璃的颜色从浅黄色变到深红棕色. 尤其是白金粒子被腐蚀进入玻璃液 后，玻璃中很容易形成纳米颗粒或者团聚形成胶体粒子，在玻璃中形成色散源，加深玻璃的颜色， 降低透过率. 1 300 ℃下，白金粒子起到晶核剂的作用，生成Bi2Pt2O7和BiB3O6晶相，导致玻璃失透.

Space-selective precipitation of Au nanoparticles inside silica gel

Au colloids were prepared by irradiation with a Nd:YAG laser. Au nanoparticles were characterized by absorption spectra, transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. It is found that the wavelength of the laser has no effect on the size but the number of the Au nanoparticles. By irradiating a transparent silica gel doped with gold ions with the focused laser in the gel and subsequent exposing in air, a space-selective pattern of letter "P" consisting of Au nanoparticles was observed inside the silica gel.

Nanosecond nonlinear absorption in Au and Ag nanoparticles precipitated glasses induced by a femtosecond laser

We obtain Au and Ag nanoparticles precipitated in glasses by irradiation of focused femtosecond pulses, and investigate the nonlinear absorptions of the glasses by using Z-scan technique with ns pulses at 532 nm. We observe the saturable absorption behavior for An nanoparticles precipitated glasses and the reverse saturable ones for Ag ones. We also obtain, by fitting to the experimental results in the light of the local field effect near and away from the surface plasmon resonance, chi(m)((3)) = 4.5 x 10(-7) and 5.9 x 10(-8) esu for m the imaginary parts of the third-order susceptibilities for Au and Ag nanoparticles, respectively. The nonlinear response of Au nanoparticles in the glass samples arises mainly from the hot-electron contribution and the saturation of the interband transitions near the surface plasmon resonance, whereas that of Ag nanoparticles in the glass samples from the interband transitions. These show that the obtained glasses can be used as optoelectronic devices suiting for different demands. (c) 2005 Elsevier B.V. All rights reserved.

Precipitation of Ge nanoparticles from GeO2 glasses in transmission electron microscope

We show, using spatially resolved energy loss spectroscopy in a transmission electron microscopy (TEM), that GeO2 and GeO2-SiO2 glasses are extremely sensitive to high energy electrons. Ge nanoparticles can be precipitated in GeO2 glasses efficiently by the high-energy electron beam of a TEM. This is relevant to TEM characterization of luminescent Ge nanoparticles in silicate glasses, which may produce artificial results. (C) 2005 American Institute of Physics.

Preparation and optical properties of silicate glasses containing Pd nanoparticles

We report the space selective precipitation of Pd nanoparticles in Pd2+ -doped silicate glass by ultrashort laser pulses irradiation and further annealing. Absorption spectra, transmission electron microscopy, refractive index measurement and Z-scan technique demonstrated that metallic Pd nanoparticles were precipitated in the glass sample after irradiation by an 800-nm femtosecond laser and subsequent annealing at 600 degrees C. We discuss a refractive index change and nonlinear absorption that combines the precipitation of Pd nanoparticles. Crown Copyright (c) 2005 Published by Elsevier B.V. All rights reserved.

Absence of room-temperature ferromagnetism in Al-codoped Zn0.95Co0.05O nanoparticles

Nanocrystalline Zn0.95-xCo0.05AlxO (x=0, 0.01, 0.05) diluted magnetic semiconductors have been synthesized by an auto-combustion method. X-ray diffraction measurements indicated that Al-doped Zn0.95Co0.05O samples had the pure wurtzite structure. X-ray absorption spectroscopy, high-resolution transmission electron microscope, energy dispersive spectrometer and Co 2p core-level photoemission spectroscope analyses indicated that Co2+ substituted for Zn2+ without forming any secondary phases or impurities. Resistance measurements showed that the resistance values of Co and Al codoped samples were still so large in the giga magnitude. Magnetic investigations showed that nanocrystalline Al-doped Zn0.95Co0.05O samples had no indication of room temperature ferromagnetism. (C) 2007 Elsevier B.V. All rights reserved.

Y2O3 stabilized ZrO2 thin films deposited by electron beam evaporation: Structural, morphological characterization and laser induced damage threshold

Four kinds of Y2O3 stabilized ZrO2 (YSZ) thin films with different Y2O3 content have been prepared on BK7 substrates by electron-beam evaporation method. Structural properties and surface morphology of thin films were investigated by X-ray diffraction (XRD) spectra and scanning probe microscope. Laser induced damage threshold (LIDT) was determined. It was found that crystalline phase and microstructure of YSZ thin films was dependent on Y2O3 molar content. YSZ thin films changed from monoclinic phase to high temperature phase (tetragonal and cubic) with the increase of Y2O3 content. The LIDT of stabilized thin film is more than that of unstabilized thin films. The reason is that ZrO2 material undergoes phase transition during the course of e-beam evaporation resulting in more numbers of defects compared to that of YSZ thin films. These defects act as absorptive center and the original breakdown points. (c) 2006 Elsevier B.V. All rights reserved.

Y2O3 stabilized ZrO2 thin films deposited by electron-beam evaporation: Optical properties, structure and residual stresses

This paper describes the preparation and the characterization Of Y2O3 stabilized ZrO2 thin films produced by electric-beam evaporation method. The optical properties, microstructure, surface morphology and the residual stress of the deposited films were investigated by optical spectroscopy, X-ray diffraction (XRD), scanning probe microscope and optical interferometer. It is shown that the optical transmission spectra of all the YSZ thin films are similar with those of ZrO2 thin film, possessing high transparency in the visible and near-infrared regions. The refractive index of the samples decreases with increasing of Y2O3 content. The crystalline structure of pure ZrO2 films is a mixture of tetragonal phase and monoclinic phase, however, Y2O3 stabilized ZrO2 thin films only exhibit the cubic phase independently of how much the added Y2O3 content is. The surface morphology spectrum indicates that all thin films present a crystalline columnar texture with columnar grains perpendicular to the substrate and with a predominantly open microporosity. The residual stress of films transforms tensile from compressive with the increasing Of Y2O3 molar content, which corresponds to the evolutions of the structure and packing densities. (C) 2008 Elsevier Ltd. All rights reserved.