Silicate layer structure

CSH samples were synthesized with a Calcium/Silicium ratio 0.9 following a soft Chemistry hydrothermal procedure which allows to produce model compounds of cement a calcio-silicate layered structure with a pristine interlamellar spacing of 14 A. 

Clay minerals have silicate layer structures of either type 1 1 or 2 1. Kaolinite is of type 1 1 and... 

XRD and TEM results, a mixed morphology including tactoids, and intercalated and exfoliated silicate layer structures... 

Silicates with layer. structures include some of the most familiar and important minerals known to man, partieularly the clay minerals [such as kaolinite (china clay), montmorillonite (bentonite, fuller s earth), and vermiculite], the micas (e.g. muscovite, phlogopite, and biotite), and others such as chrysotile (white asbestos). 

Tetrahedra linked via three vertices correspond to a composition MX1 1X3 2 or MX2 5 = M2X5. Small units consisting of four tetrahedra are known in P4O10, but most important are the layer structures in the numerous sheet silicates and aluminosilicates with anions of the compositions and [AlSiOj-]. Because the terminal vertices of the single... 

Most nanocomposite researchers obdurately believe that the preparation of a completely exfoliated structure is the ultimate target for better overall properties. However, these significant improvements are not observed in every nanocomposite system, including systems where the silicate layers are near to exfoliated [29]. While, from the barrier property standpoint, the development of exfoliated nanocomposites is always preferred, Nylon 6-based nanocomposite systems are completely different from other nanocomposite systems, as discussed [3,8]. 

The shift factor b, shows a large deviation from a simple density effect, it would be expected that the values would not vary far from unity [44], One possible explanation is an internal structure development occurring in PLANCs during measurement (shear process). The alignment of the silicate layers probably enables the PLFNC melts to withstand the shear force, thus leading to the increase in the absolute values of G (co) and G"(co). 

Galgali and his colleagues [46] have also shown that the typical rheological response in nanocomposites arises from frictional interactions between the silicate layers and not from the immobilization of confined polymer chains between the silicate layers. They have also shown a dramatic decrease in the creep compliance for the PP-based nanocomposite with 9 wt% MMT. They showed a dramatic three orders of magnitude drop in the zero shear viscosity beyond the apparent yield stress, suggesting that the solid-like behavior in the quiescent state is a result of the percolated structure of the layered silicate. 

The crystal structure of ECS-2 can be described by the stacking of alumino-silicate layers held together by phenylene groups (Fig.l). These layers are composed by aluminum centered tetrahedra bonded to [Si03C] tetrahedra. 

A central question with respect to supported metal catalysts is that of the structure of the metal-support interface. Various possibilities have been proposed, varying from interfaces consisting of a mixed metal aluminate or silicate layer [17] or the presence of metal ions which serve as anchors between particle and support [18] to the attractive interaction between ions of the support and the dipoles that these ions induce in the metal particle [19]. EXAFS highlights the atomic surroundings of an atom in the catalyst, and if the supported metal particles are sufficiently small, oxygen atoms in the metal-support interface give a measurable contribution to the EXAFS spectrum. 

Study of hydrated kaolinites shows that water molecules adsorbed on a phyllosilicate surface occupy two different structural sites. One type of water, "hole" water, is keyed into the ditrigonal holes of the silicate layer, while the other type of water, "associated" water, is situated between and is hydrogen bonded to the hole water molecules. In contrast, hole water is hydrogen bonded to the silicate layer and is less mobile than associated water. At low temperatures, all water molecules form an ordered structure reminiscent of ice as the temperature increases, the associated water disorders progressively, culminating in a rapid change in heat capacity near 270 K. To the extent that the kao-linite surfaces resemble other silicate surfaces, hydrated kaolinites are useful models for water adsorbed on silicate minerals. 

NMR properties, 33 213, 274 in nutation-NMR spectroscopy, 33 333 in sheer silicate smdies of, 33 340-341 layer structure, 32 184-186 on metal surfaces, 32 194-197 model, oscillatory reactions, 39 97-98 number... 

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