Silicate chemistry

Vaia, R.A., Ishii, H. and Giannelis, E.P. 1993. Synthesis and properties of two dimensional nanostructures by direct intercalation of polymer melts in layered silicates. Chemistry of Material 5 1694-1696. 

Because this book presents information on many areas of inorganic chemistry, a detailed discussion of silicates cannot be presented. Although silicate chemistry is a very complex field, there are some pervasive principles. It should first be mentioned that an oxide is easily converted to a hydroxide by reaction with water,... 

I. V. Grebenshchikov Institute of Silicate Chemistry, USSR Academy of Sciences and A. A. Zhdanov State University of Leningrad, Leningrad, U.S.S.R. 

The authors are very grateful to the University of Veszprem, Department of Silicate Chemistry and Material Sciences, Hungary for the XRD and SEM facilities. 

The chemistry of zeolites has considerable commercial application. However, the details of this important topic are beyond the scope of this book. As has been shown, the silicates constitute an enormous range of materials, and additional information on the various phases of silicate chemistry is available in the references listed at the end of this chapter. 

In general, the crystal chemistry of borates is similar to that of silicates differences arise from the fact that boron combines with oxygen not only in four-fold (tetrahedral) but also in three-fold (trigonal planar = triangular) coordination. As a result, silicate chemistry is considerably less complicated than borate chemistry. 

Deryagin B.V., Krotova N.A, Smilga V. P., Adhesion of solids. Moskva Nauka, 1973. Sichev M.M. Modem conceptions of the nature of cement components inorganic binders and the role of polymer formations. In Chemistry and technology of silicates and refractory materials. Institute of silicate chemistry of l.V. Grebenschikov Leningrad Nauka, 1989. 

Silica.tes, For many years, siUcates have been used to inhibit aqueous corrosion, particulady in potable water systems. Probably due to the complexity of silicate chemistry, thek mechanism of inhibition has not yet been firmly estabUshed. They are nonoxidizing and requke oxygen to inhibit corrosion, so they are not passivators in the classical sense. Yet they do not form visible precipitates on the metal surface. They appear to inhibit by an adsorption mechanism. It is thought that siUca and kon corrosion products interact. However, recent work indicates that this interaction may not be necessary. SiUcates are slow-acting inhibitors in some cases, 2 or 3 weeks may be requked to estabUsh protection fuUy. It is beUeved that the polysflicate ions or coUoidal siUca are the active species and these are formed slowly from monosiUcic acid, which is the predominant species in water at the pH levels maintained in cooUng systems. 

Institute of Silicate Chemistry RAS, Saint-Petersburg, Russia... 

Absorption spectra were measured with a spectrophotometer MS-122. Photoluminescence (PL) was recorded with a fluorimeter Fluoromax-2 (A-ex = 325 nm). For SAXS measurements a device of the Institute of Silicate Chemistry of HAS, Russia (CuKa radiation with a Ni filter) was used. 

Double-salt Formation. This is an important class of solid reactions, including all the reactions of silicate chemistry, spinel formation, the formation of Ag Hgl, etc. These reactions may proceed by movement of one or more kinds of ions. In spinel formation only one kind of ion is normally mobile in the product lattice, and reaction occurs therefore at the phase boundary of the inactive oxide and the spinel. In the reaction between... 

Now that the phase diagram has told us what will form during NazO reaction with a fireclay refractory, we must evaluate whether or not these phases create a serious problem. This information can be obtained from various sources, especially any text on high-temperature silicate chemistry. The important information follows ... 

In the silicate chemistry, the oxides are divided into three principal groups ... 

Reactions 1-3 indicate that dimerization is preferred at low pH. If one includes reactions for the formation of higher order oligomers and their neutralization (i.e., the analogs of reaction 2 and 3), then it is concluded that the extent of oligomerization increases with decreasing pH. This trend is in excellent agreement with the literature on silicate chemistry (7.9.20 ) and is exemplified by the results presented in Figures 1-3 for individual cations. 

It will be seen how much more illuminating is this formulation of chlorite than the empirical formulation given earlier not only does it express the correct 0 (Si, Al) ratio of 10 4 but it also shows that Mg2+, Al3+ and OH ions all appear in the structure in two distinct roles. Few more striking examples could be given of the value of X-ray structural studies in resolving the complex problems of silicate chemistry. 

Silica gels, porous glasses, and silica powders were prepared by A. Kiselev, Nikitin, and co-workers (Moscow State University, Moscow) (2, 3, 26, 27, 74-81) Dzisko, Fenelonov, and co-workers (Institute of Catalysis, Siberian Division of the U.S.S.R. Academy of Sciences, Novosibirsk) (82, 83) Zhdanov and co-workers (Institute of Silicate Chemistry, the U.S.S.R. Academy of Sciences, Leningrad) (84-87) Belotserkovsky, Kolosentsev, and co-workers (Technological Institute, Leningrad) (59-61) Neimark, Sheinfain, and co-workers (Institute of Physical Chemistry, the Ukrainian S.S.R. Academy of Sciences, Kiev) (28, 29) Chuiko (Institute of Surface Chemistry, the Ukrainian S.S.R. Academy of Sciences, Kiev) (88) and others. 

Zhdanov (Institute of Silicate Chemistry, the U.S.S.R. Academy of Sciences, Leningrad) (154) showed (1949) that the adsorption of water vapor by SiC>2 (porous glasses, silica gels) strongly depends on the temperature of the preliminary thermal treatment of the adsorbent. Calcination of 300-500 °C resulted in a sharp decrease in the adsorption of H2O at low values of pressure over initial pressure p/p0 (<0.3), and the adsorption isotherms were found to be irreversible. On the other hand, the adsorption isotherms of water on silica subjected to calcination in vacuo at <500 °C (but after the sample was kept in contact with water vapor or liquid water at room temperature) again became reversible that is, the adsorption activity of Si02 was restored. 

Zhdanov, S. P. Summary of Dissertation. Leningrad, Institute of Silicate Chemistry, the USSR Academy of Sciences, 1952. 

Tb better understand the magnesium and silicate chemistry of the rock-fluid system, the solubilities of talc, sepiolite, and diopside are compared in Figure 4. These three minerals were plotted because they have been reported to be stable in high silica, alkaline systems similar to the one under study (19-23). The mineral stability lines were developed using the following equations ... 

Institute of Silicate Chemistry of the USSR Acad. Sci., Leningrad, USSR... 

Among a small group of silicates that can be obtained from aqueous solutions at room temperatuiTe and normal pressure are silicates with complex cations. Silicates with chelate complexes of transition metals were first obtained by V. Molchanov and N.Pri-khid ko at the Institute of Silicate Chemistry (jl,). Silicates with alkylammonium cations were prepared in aqueous solutions by S. Glixelli and T. Krokowski ( ) and D. Hoebbel and W, Wieker (3),... 

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