Three-layer structure, formation with

Taken from the three spontaneous symmetry-breaking events leading to this layer structure [formation of layers with long-range orientational order of the director (Sm), tilt of the director from the layer normal (C), and polar orientation of the molecular arrows (P)], we term phases of this type SmCP. All of the complex textures and EO behavior of NOBOW in the B 2 phase can be understood in terms of various stacking modes of SmCP layers as shown in Figure 8.23. 

In the aluminophosphate family, three main structural classes with different metal to phosphorus ratios are known. The layered aluminophosphates normally have P/Al ratios of 4 3 and 3 2 and a new series with P/Al ratio of 2 1 has been reported [25]. The templates play an important role in the formation of these materials and there have been some attempts to rationalize the formation of these solids [25]. The two-dimensional architecture is generally formed by strictly alternating P04 and A104 tetrahedra. Of the four oxygen atoms coordinated to each tetrahedral phosphate, three are shared with adjacent A1 atoms,... 

The Wirth model has a two-layer structure, whilst the current model has a three-layer structure, which represents the mechanisms involved with the formation of the unstable zone. 

Many three-dimensional polymeric substances are particularly refractory, insoluble and unreactive. One- and two-dimensional polymers tend to be more soluble. For example, dichlorides and trichlorides of the 3d elements are generally quite soluble in weakly-polar organic solvents such as alcohols, ethers and ketones. The driving force here is the formation of complexes with the solvent molecules. These compounds are also soluble in water, with some degree of hydrolysis. Aluminium(III) chloride (which has a layer structure similar to that of CrCl3) dissolves in some non polar organic solvents, such as benzene, in which it forms A12C16 dimers. 

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