Phyllosilicates framework

Metal cations Organic moieties covalently attached to phyllosilicate framework References... 

Framework - phyllosilicate/microcrystalline quartz fault rocks This class of fault rock is introduced here to describe fault rocks which form in sediments with concentrations (>20%) of dissolvable sponge spicules and varying amounts (15-40%) of phyllosilicates (Fig. 2d). Although not common, sediments with high sponge spicules contents are prone to the development of fault rocks by the cataclasis, dissolution and reprecipitation of silica. The process may be initiated by the collapse of secondary pores created by spicule dissolution and induce the redistribution of more soluble material by mixing. 

Abstract Clays are ubiquitous constituents of the Earth s crust that serve as raw materials for traditional ceramics. Mineralogically, clays are phyllosilicates or layered aluminosilicates. Bonding is strong within layers, but weak between layers, allowing clays to break into micrometer-sized particles. When mixed with water, clays develop plasticity and can be shaped easily and reproducibly. When heated, clays undergo a series of reactions that ultimately produce crystalline mullite and a silica-rich amorphous phase. Beyond the structure and properties of clays, the science that developed to understand traditional ceramics continues to serve as the framework for the study of advanced ceramics. 

In phyllosilicates, metal atoms in the octahedral sheet are surrounded by 3 (dioctahedral framework) or 6 (trioctahedral framework) nearest six-fold coordinated cations (Oct), and by 4 nearest four-fold coordinated Si,Al atoms (Tet) from the... 

M stands for cations such as protons, alkali, or alkaline earths, n stands for then-valency, X indicates numbers between 2 and 40, and y indicates numbers between 1 and 20. The metal ions are exchangeable xSi02 comprises the tetfahedral [SiOJ units of the framework, and nH20 comprises all structural hydroxyl groups and the interlayer water molecules. This formulation refers to layered silicate hydrates of different structures, cationic forms, and degrees of hydration. It does not differentiate the M-SHs from other silicate types, such as nesosilicates, inosilicates, and phyllosilicates. Liebau [16] proposed a classification criterion (Table 2) based on the 0/Si ratio in the framework. The layered metal silicate hydrates with values between 2.25 and 2.1 are positioned between the traditional phyllosilicates (0/Si ratio 2.5) and the tectosilicates (0/Si ratio 2.0). 

Figure 1. Illustration of the linkage of Si04 tetrahedra in different classes of silicates, (a) Nesosilicates (separate tetrahedra) (b) sorosilicates (linked tetrahedra) (c) cyclosilicates (closed rings) (d) and (e) inosilicates (single and double chains) (f) phyllosilicates (sheets) (g) tectosilicates (framework).

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