Layered silicate phase

Figure 10-2 displays the powder XRD spectra of the five samples, as synthesized, and Table 10-3 shows, the X-ray powder diffraction data for the layer silicate phases. These spectra exhibit the charact stic bands (hk) at 4.45-4.47A, at nearly 2.56A, and at 1.49A. The 1.49A band (060) indicates the dioctahedral nature of the layer silicates. Due to the basal reflection, there is also a peak in the low-angle region, the value of which varied with interlayer cation nature and relative humidity (Table 10-4, third and fourth columns). Some samples show other peaks that may be indexed as (001) reflections such as (002), (004) or (006). 

The lithium disilicate layered silicate phase, Li2Si205, is the primary crystal phase. In addition, the growth of lithium disilicate may be initiated by the primary crystallization of the precusor chain silicate, lithium metasilicate, Li2Si03. 

Bronsted acid sites) or metal atoms with unsatisfied coordination (Lewis acid sites) react with water to form surface charge (13). Isomorphic substitution in the interlayer region of layered silicates results in a negative surface charge. In each case chemical "exchange" of ions between phases results in the formation of surface charge and the development of an electrical potential. 

The clay fraction, which has long been considered as a very important and chemically active component of most solid surfaces (i.e., soil, sediment, and suspended matter) has both textural and mineral definitions [22]. In its textural definition, clay generally is the mineral fraction of the solids which is smaller than about 0.002 mm in diameter. The small size of clay particles imparts a large surface area for a given mass of material. This large surface area of the clay textural fraction in the solids defines its importance in processes involving interfacial phenomena such as sorption/desorption or surface catalysis [ 17,23]. In its mineral definition, clay is composed of secondary minerals such as layered silicates with various oxides. Layer silicates are perhaps the most important component of the clay mineral fraction. Figure 2 shows structural examples of the common clay solid phase minerals. 

The mineral phase. Mineral colloids are composed of layered silicates and amorphous metal hydroxides. The two basic building layers of the silicates are (i) a tetrahedral silicon dioxide layer modified by occasional substitution by Al and (ii) an octahedral A1 oxyhydroxide layer with occasional substitution by Mg2+, or... 

We have presented several examples of the successful preparation of rubber nanocomposites with layered silicate as the inorganic phase. This review explores the idea that the designing and compounding are key factors in obtaining the... 

Most likely, the chemical system remains closed, as far as the other components in the silicate phases are concerned, as diagenesis or low grade metamorphism becomes more evident. Although there may be transfer of calcium, it seems, from bulk chemical analysis, that there is no systematic increase in potassium nor decrease in sodium content of argillaceous sediments. The transfer of Na and K is between the two size fractions—clay and coarse fraction—or between phyllosilicates and tectosilicates. Albitization of argillaceous rocks should be a common phenomenon where mixed layered phases are predominant in clay assemblages and especially evident in the illite-chlorite zone. 

Batteries. Many 7t-conjugated polymers can be reversibly oxidized or reduced. This has led to interest in these materials for charge-storage batteries, since polymers are lightweight compared to metallic electrodes and liquid electrolytes. Research on polymer batteries has focused on the use of polymers as both the electrode and electrolyte. Typical polymer electrolytes are formed from complexes between metal-ion salts and polar polymers such as poly(ethyleneoxide). The conductivity is low at room temperature due to the low mobility of cations through the polymer-matrix, and the batteries work more efficiendy when heated above the glass-transition temperature of the polymer. Advances in the development of polymer electrolytes have included polymers poly(ethylene oxide) intercalated into layered silicates (96). These solid-phase electrolytes exhibit significantly improved conductance at room temperature. 

On the whole, the large group of phosphorus compounds can be combined successfully with OMLS, because of the possibility to combine the barrier properties of layered silicates, and to their reinforcement action on the charred residue promoted by the phosphorus additives. In addition, the formation of various aluminophosphate species and the specific action in the gaseous phase of some phosphorus FR can complicate the optimization of the FR performance and the interpretation of the synergistic effects observed. 

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