Silicate and Aluminosilicate Glasses

Thus an acid-base reaction involves the transfer of an oxide ion (compared with the transfer of a proton in the Bronsted theory) and the theory is particularly applicable in considering acid-base relationships in oxide, silicate and aluminosilicate glasses. However, we shall find that it is subsumed within the Lewis definition. 

Pederson, L. R., McGrail, B. P., McVay, G. L., Petersen-Villalobos, D. A. Settles, N. S. 1993. Kinetics of alkali silicate and aluminosilicate glass reactions in alkali chloride solutions Influence of surface charge. Physics and Chemistry of Glasses, 34, 140-148. 

Murdoch, J. B., J. F. Stebbins, and I. S. E. Carmichael (1985). High-resolution Si NMR study of silicate and aluminosilicate glasses the effect of networkmodifying cations. Amer. Mineral. 70, 332—43. 

Various ID and 2D high-resolution solid-state NMR techniques have been applied to hydrous silicate and aluminosilicate glasses simple acquisition, CPMAS, HETCOR, dipolar dephasing, spin counting, DQ correlation, and rotational echo double resonance (REDOR). ... 

Figure 14. Deviation from additivity of diffusion activation energy in mixed alkali silicate and aluminosilicate glasses.

E. Gambuzzi, A. Pedone, M.C. Menziani, F. Angeli, D. Caurant, T. Charpentier, Probing silicon and aluminium chemical environments in silicate and aluminosilicate glasses by solid state NMR spectroscopy and accurate first-principles calculations. Geochim. Cosmochim. Acta 125, 170-185 (2014)... 

Silicon and aluminium chemical environments in silicate and aluminosilicate glasses were examined by Gambuzzi et al. They looked at the relationships between the local structural environments and the Si and Al NMR parameters are highlighted and showed that the isotropic chemical shift of both Si and Al increases of about -f 5 ppm for each Al added in the second sphere and both the Si and Al isotropic chemical shifts linearly decrease with the reduction of the average Si/Al-O-T bond angle. 

T. J. Kiczenski, L.-S. Du, J. F. Stebbins, F-19 NMR study of the ordering of high field strength cations at fluoride sites in silicate and aluminosilicate glasses, J. Non-Cryst. Solids, 337, 142-149 (2004). 

Experimental studies are being conducted to obtain the stmcture of glasses. The crystal structure can be determined accurately, whereas the glass structures cannot be determined precisely. Usually, the most common glasses are silicate, borate, aluminosilicate, phosphate and germinate. In this section, we discuss the structure of borate, silicate, and aluminosilicate glasses in detail which are within the scope of this book. 

NMR of hydrous glasses. The effect of water in silicate and aluminosilicate... 

Rather conventional means for the manufacturing of hollow microspheres with diameters between 1 and 1000 pm have been developed [11.9]. Methods include spray drying and dripping as well as emulsion or suspension techniques. The microspheres feature low effective and bulk densities coupled with high specific surfaces. Typical wall thicknesses are in the range 1-10% of the diameter. Potential wall materials include glass, ceramic and mixed oxides, silicates and aluminosilicates, polymers and polycondensates, and metals. Surface phenomena, which may be modified by chemical reactions, additives, and/or post-treatments, play an important role for microsphere formation, properties, and stability. Fig. 11.12 is the photomicrograph of a calcined hollow microsphere [11.9]. 

Water diffusion and solubility have been measured for a wide range of glass compositions, including a number of studies for vitreous silica, alkali silicates and aluminosilicates, soda-lime-silicates, and alkali borates and germanates. Early models for diffusion suggested that the diffusivity of water in melts was controlled entirely by the viscosity of the melt, as predicted by the Stokes-Einstein equation. This equation predicts that the diffusivity of a spherical particle in a liquid is inversely proportional to the viscosity. This hypothesis has been shown to be quantitatively incorrect by 4 orders of magnitude, to predict a much... 

Hydroxymethyl-2,5-diphenyloxazole used as a liquid scintillator was incorporated via covalentbonding into a porous silica glass (Hamerton, 2000). The sol-gel glasses were found to be highly efficient detectors of 8-radioactivity. Chemiluminescence of luminol was observed in silicate and aluminosilicate sol-gel glass (Akbarian, 1993). 

---