Hajimu Wakabayashi

Structural Study of Al(acac)3 Catalyzed CH3SiO3/2 Gel

A transparent CH3SiO3/2 gel and an opaque one have been prepared from methyltriethoxysilane. Al(acac)3 is added to obtain the transparency. The two gels are studied by XRD, NMR and infrared spectroscopy. Some amount of silanols remains in the form of T2(CH3SiO(OH)) in the transparent gel, but few in the opaque gel. There is a diffraction peak reflecting intermolecular correlation in the XRD curves, which appears broader at a lower angle in the transparent gel than in the opaque gel. These results are discussed by assuming a larger hindrance in polymerization of silanols in the transparent gel.

Haven ratio in mixed alkali glass

Abstract It is known that the Haven ratios, H R , in mixed alkali glasses increase anomalously. The authors have attempted to explain quantitatively such anomalous behavior by introducing the thermodynamic activity term in the Nernst-Planck equation, which results from the attractive interaction between dissimilar alkali ions via oxygen ion. As a result, it was found that the apparently large values of H R in the mixed alkali glasses can be reduced to the same as in the single alkali glasses when corrected by the thermodynamic term. This fact also indicates that the ionic diffusion mechanism in mixed alkali glasses does not differ from that in single alkali glasses.

Depth profiling by XPS for corroded glass

Abstract The depth profiles of glass surface layers were measured by XPS with Ar ion sputtering, although sputtering affects the glass composition. Deposited carbon was the best mask material for sputtering because of its low sputtering yield, clean surface and clear boundary. A glass surface treated by Soxhlet leaching apparatus was compared with untreated glass; their intensity ratio indicated the reasonable change of depth profile representing selective leaching of the alkali component.

Ionic Motion and Structure of Ion Conductive Glasses

The dynamic structure of xLi 2 S-Ga 2 S 3 -6GeS 2 (x=4 and 6) glasses has been investigated by 7 Li nuclear magnetic resonance. In two samples similar values of spin-lattice relaxation time (T 1 ) were obtained. The relaxation mechanism at 20MHz and 78MHz is therefore attributed to the local motion of lithium ions. In the glass corresponding to x=6, which shows higher conductivity, the slow motion of ions showing an activation energy of 24.3kJ/Mol has been detected by the spin-lattice relaxation time in the rotating frame (T 1p ). This value is comparable to the activation energy determined by the conductivity. The existence of this mode is supported by the motional narrowing of the line width which is sensitive to the motion less than 10kHz.

Nonlinear Optical Properties of Au Colloid-Doped Glasses

Degenerate four-wave mixing experiments have been performed for Au colloid-doped glasses prepared by melting and sputtering methods. The nonlinear optical properties of the glasses are discussed from viewpoint of the concentration of the Au colloid particles and the thickness of the glasses. We also discuss the dependence of the nonlinear properties on the pulse duration of laser for the measurements, and a very slow relaxation.

Insight into Mechanical Properties of CH3SiO3/2 Film

Youngs modulus and stress-optical coefficient of self-sustained gel film of CH3SiO3/2 were measured. Youngs modulus varied from 1.1 to 1.5 GPa, depending on the structural state of the film. It increased with an increase in the degree of polymerization that was induced by heat treatments, and also increased with subsequent exposure to the ambient condition. The stress-optical coefficient was 6.3 × 10−12 Pa−1 for a sample treated at 120°C. The compliance of the film seems to depend mainly on the intermolecular structure of Si–CH3...CH3–Si as well as hydrogen bonding due to silanols and adsorbed water.

Preparation of Hydrated Glass as a Model of Long-Term Leached Nuclear Waste Glass

Hydrated glass was prepared by the treatment in an autoclave. Specimen in a good state and was obtained under unsaturated water vapor pressure conditions. The obtained glass has a silica-rich hydrated layer and proved to be more durable than the original glass. There are some kinds of hydroxyl species in the hydrated glass and there are some patterns in the depth profile of water, indicating that the rate-controlling process is not a simple diffusion and the hydration process is a complicated reaction depending on the conditions. Water in hydrated glass is tightly bonded and a disintegration of hydrated glass in this study occurs at more than 560 C.

Distribution of Impregnated Component and Nonuniformity of Colloidal Silica in Porous Glass

Porous glass prepared by acid leaching of phase separated glass contains colloidal silica, resulting in the nonunif ormity in the porous glass. Porous glass rods were impregnated with aluminum nitrate solutions, and some of them were treated subsequently with ammonia to precipitate aluminum hydroxide. Then the porous glasses were sintered to form nonporous glasses. The concentration profile of aluminum in the sintered glasses was studied with reference to the nonunif ormity. The aluminum concentration in the impregnated and ammonia-treated specimens was high at the surface region and decreased toward the center. This fact coincides with the distribution of porosity which is high at the surface region. The concentration difference between the as-impregnated and impregnated and ammonia-treated specimens was large at the center and decreased toward the surface, in good correlation with the distribution of the surface area which is high at the center. A narrow gap with a low aluminum concentration was observed at the center of the impregnated specimen and was ascribed to the very densely deposited colloidal silica.