Formation of silver colloids in silver ion-exchanged soda-lime glasses during annealing

The structural and compositional changes of the soda-lime glasses during the formation of the silver colloids were analyzed by the X-ray Photoelectron Spectroscopy (XPS) in order to examine the silver colloid formation mechanism. The in situ behavior of silver and SiO₂ networks on the surfaces of silver ion-exchanged soda-lime glasses during heating and cooling processes in ultra-high vaccum was monitored. The results showed that silver diffuses toward the surface, precipitates, and crystallizes during heating and the total silver surface concentration is slowly increased during cooling. The concentration changes of oxidized and neutral Ag, a new non-bridging oxygen species (NBO^*), and a new silicon species (Si[a]) were applied to deduce a disappropriation reaction mechanism of Ag⁺ on the surface during annealing. The SiO₂ network is modified at temperatures below 350°C to accommodate more silver on the surface and to balance the extra charge carried by the Ag⁺. That the SiO₂ network polymerizes during annealing was deduced from the results of the higher binding energies of Si2p and O1s after annealing. This observation suggests that the reduction of the Gibbs free energies and the relaxation of tensile stress result in the formation of the silver colloids under thermal annealing.     

Micromachining soda-lime glass by femtosecond laser pulses

The physical process of forming a modified region in soda-lime glass was investigated using 1 kHz intense femtosecond laser pulses from a Ti: sapphire laser at 775 nm. Through the modifications induced by the femtosecond laser radiation using selective chemical etching techniques, we fabricated reproducible and defined microstructures and further studied their morphologies and etching properties. Moreover, a possible physical mechanism for the femtosecond laser modification in soda-lime glass was proposed.     

Low temperature hermetic laser-assisted glass frit encapsulation of soda-lime glass substrates

Room temperature and low temperature (120 °C) laser-assisted glass frit bonding of soda-lime glass substrates are accomplished in this work. The locally laser melted bonding showed hermeticity with helium leak rate of <5×10⁻⁸ atm cm³ s⁻¹, maintaining its leak rate even after standard climatic cycle tests. Small size devices were bonded at room temperature while larger areas were sealed at the process temperature of 120 °C. The sealing parameters were optimized through response surface methodology that makes the process capable for further development regardless of device size.     

Buried ion-exchanged glass waveguides: burial-depth dependence on waveguide width

A detailed theoretical and experimental study of the depth dependence of buried ion-exchanged waveguides on waveguide width is reported. Modeling, which includes the effect of nonhomogeneous time-dependent electric field distribution, agrees well with our experiments showing that burial depth increases linearly with waveguide width. These results may be used in the proper design of integrated optical circuits that need waveguides of different widths at different sections, such as arrayed waveguide gratings.     

Formation of argentic clusters and small Ag nanoparticles in soda-lime silicate glass

The formation of argentic clusters and very small Ag nanoparticles of 0.5 to 2 nm size in commercial soda-lime glass silver-doped by Ag/Na ion exchange in a mixed nitrate melt has been studied by electron microscopy and EXAFS. Particles formation was induced already during the ion exchange procedure, or by subsequent ion irradiation with 1.5 MeV He⁺ or 3 MeV Au⁺. The presence of nanoparticles was also macroscopically revealed by their surface plasmon resonance. The structural characterization indicates that specific configurations of silver oxide-like structures, so-called argentic clusters, are involved in the initial stage of nanoparticles formation.     

Water cleaning ability and local structure of iron-containing soda-lime silicate glass

A relationship between waste-water cleaning ability and local structure of iron-containing soda-lime silicate glass, 15Na₂O·15CaO·xFe₂O₃·(70-x)SiO₂ (x?= 10–50 in mass%), abbreviated as NCFSx glass, was investigated by means of ⁵⁷Fe-Mössbauer spectroscopy, redox titration with KMnO₄ for the determination of chemical oxygen demand (COD) and inductively coupled plasma optical emission spectroscopy (ICP-OES). Mössbauer spectra of NCFSx glass with “x” of 10 and 30 were composed of two doublets: one due to Fe^IIIO₄ tetrahedra (T _d) with isomer shift (δ) of 0.23–0.26 mm s^???1 and quadrupole splitting (Δ) 1.01–1.04 mm s^???1, and the other due to Fe^IIO₆ octahedra (O _h) with δ of 1.00–1.03 mm s^???1 and Δ of 2.03–2.05 mm s^???1. Absorption area for Fe^II(T _d) was decreased from 9.7 to 6.5 and 0.0 % when “x” was increased from 10 to 30 and 50. A leaching test performed with 500 mL of artificial waste water and 2.0 g of NCFS50 revealed waste-water cleaning ability of soda-lime glass, e.g., COD was reduced from 280 to 55.2 mg L^???1 after 10 day-leaching. After 10 day-leaching, it proved that iron was dissolved into waste water to a level of 5.3 $_{7} \times 10^{-1}$  mg L^???1. These results prove that organic matter could be effectively decomposed with iron-containing soda-lime silicate glass.     

Laser-induced breakdown of soda-lime glass microspheres using Nd:YAG laser

The Nd:YAG laser-induced breakdown of 20 μm glass microspheres was investigated using time-resolved optical shadow and Schlieren images. Time-resolved imaging showed the location of the initial breakdown and the shockwave motion over its first 400 μm of expansion. Measured shockwave velocities were in the range of 1–10 km/s and showed a linear dependency on laser fluence within 30 ns.     

Radiation-enhanced diffusion in ion-implanted glass

The Rutherford backscattering technique was used to characterize the purposedly added cesium impurities in soda-lime glass. The impurities were introduced into the glass matrix by an ion-exchange diffusion process at room temperature. The diffusion coefficient of cesium was determined from the measured depth profiles. The diffusion of the cesium impurities stimulated by 280 keV Kr⁺-ion beam irradiation was also studied. The depth distributions obtained are discussed using the model of radiation enhanced diffusion. Results are compared with theoretical values based on transport of ions in matter calculations and other experimental work.On sabbatical leave at Applied Science University, Physics Department, P. O. Box 926296, Amman, Jordan     

Longitudinal and bulk compressibility of soda-lime glass at pressures to 10 GPa

The longitudinal and bulk compressibilities of soda-lime glass are measured. The longitudinal compressibility is reconstructed by analyzing the compression wave profile in the approximation of a simple centered wave. The bulk compressibility is determined by the method of mixtures. Under strong uniaxial compression, Poisson’s ratio is found to increase up to its ultimate value, v = 0.5. Because of a strong dependence of Poisson’s ratio on the deviator stress, the mean mechanical impedance of the glass rises during its compression failure.     

后处理对离子交换磷酸盐玻璃平面光波导的影响

研究了退火和二次离子交换对Er3+/Yb3+共掺的磷酸盐玻璃平面光波导传输特性的影响。在退火过程中，由于热效应和波导层Ag+离子的浓度差使得Ag+离子重新分布；随着退火时间的延长和温度的升高，光波导模式数目逐渐增加，波导层深度加深，且波导表面折射率与玻璃基质折射率差减小，退火扩散深度与退火时间的平方根成正比。电子探针结果显示在二次离子交换后形成了掩埋式的光波导，Ag+离子浓度接近二次方分布，而掩埋式的光波导有助于降低光波导的传输损耗。     

Laser-induced sign reversal of the nonlinear refractive index of Ag nanoclusters in soda-lime glass

Received: 16 February 1998     

Numerical study of an ion-exchanged glass waveguide using both two-dimensional and three-dimensional models

A numerical study is carried out to compare the two-dimensional (2-D) case and three-dimensional (3-D) case for the modelling of an ion-exchanged glass waveguide. It is shown that different waveguide widths on the photomask correspond to different ion concentration distributions after an annealing process. A numerical example is presented of two waveguide sections with different widths indicates that due to the abrupt change of the waveguide width, a 3-D theoretical model is required for an accurate prediction of the parameters of ion-exchanged glass waveguides. The good agreement between the modelled and measured results proves that the developed 3-D numerical model can be beneficially utilized in the generalized design of optical devices based on ion-exchange waveguides.     

Copper nanocluster diffusion in carbon nanotube

The diffusion of copper nanocluster in carbon nanotube was investigated using a classical molecular dynamics simulation and three empirical potential functions. The results indicated a growth mechanism of the copper-filled ultra-thin carbon nanotubes: the copper nanoclusters inserted into carbon nanotubes swiftly migrate along the tube axis, and then the copper nanowires grow in the ultra-thin carbon nanotubes. Periodic energy barriers in the carbon nanotubes induced the directional movement of copper nanoclusters in the carbon nanotubes. The diffusion speeds of copper nanocluster in the carbon nanotube showed the Arrherius relation.     

Copper diffusion in TaN-based thin layers

The diffusion of Cu through TaN-based thin layers into a Si substrate has been studied. The barrier efficiency of TaN/Ta/TaN multilayers of 150 nm in thickness has been investigated and is compared with that of TaN single layers. Thermal stabilities of these TaN-based thin layers against Cu diffusion were determined from in situ X-ray diffraction experiments, conducted in the temperature range of 773-973 K. The TaN/Ta/TaN barrier appeared to be more efficient in preventing Cu diffusion than the TaN single layer.     

Spin diffusion in a Heisenberg spin glass

Using a combination of analytic and Monte Carlo techniques we obtain estimates for the spin diffusion constant and spin conductivity in a classical simple cubic Heisenberg spin glass which has a Gaussian distribution of exchange interactions between nearest neighbors.     

Lightguiding in ion-exchanged glasses

A comparison is made of different Gaussian refractive index distributions in waveguides formed by thermal diffusion of silver ions into glass. Guides prepared for various diffusion times are investigated. It is shown that only one set of mode indices is insufficient to determine whether some index profile asymmetry exists.     

Modal dispersion phase-matched frequency doubling in composite planar waveguide using ion-exchanged glass and optically nonlinear poled polymer

We report on the fabrication and characterization of composite planar waveguides for frequency doubling. Modal dispersion phase matching is obtained for TM₀ fundamental and (TM₁, TM₂) harmonic wavelength. The experimental conversion efficiency was η=0.45% with an SH wavelength of 0.516 μm for TM₀^ω–TM₂^2ω mode conversion. The phase-matching condition can be fulfilled by adjusting the diffusion time of ion-exchange and the thickness of the polymer layer.