Studying shapes Lattice types

The best formed plate textures are found in crystals with a layer lattice, and generally in all crystals having the form of thin plates. Diffraction pattern (Fig.7) indicates a texture of this type, and was obtained from crystals in the shape of thin hexagonal plates. The specific role of the oblique-texture type electron diffraction patterns have in the study of clay minerals having layer structures (B.B.Zviagin, 1964, 1967). 

In the solid state, molecules line up in a pattern forming a crystal lattice similar to that of an ionic solid, but with less attraction between particles. The structure of the crystal lattice depends on the shape of the molecule and the type of intermolecular force. Most information about molecules, including properties, molecular shape, bond length, and bond angle, has been determined by studying molecular solids. 

ZSM-5 zeolites having three types of extra lattice alumina, namely acid insoluble extra framework alumina (AIEFAL), amorphous alumina (AMAL) and binder alumina (BNAL) were studied. Microcalorimetric acid strength distribution studies indicated the presence of very strong acid sites in the sample containing AIEFAL. Presence of amorphous alumina did not show any significant influence on acid strength distribution. But, the amount of poly aromatic compounds formed in n-heptane aromatization reaction over this catalyst is more, indicates the occurrence of non-shape selective surface reactions on this alumina. Presence of binder alumina showed the positive effect on stability in activity of n-heptane aromatization reaction. A common phenomenon observed with all the catalysts is the fast deactivation of strong acid sites. 

Another type of derivatized silica surface that has received considerable attention is Cis-derivatized silica gel that is, silica gel that has been silylated with reagents such as Cl(CH3)2Si(CH2)i7CH3 (45-51). This system was studied via 13C NMR (47) and 2H NMR spectroscopy (45) as a function of surface loading of the Cis chains and of certain added liquids. The ability of cross polarization to select static components of a surface derivative relative to more mobile components—which would be emphasized by non-CP (single-pulse) techniques that rely on direct 13C spin-lattice relaxation—can be seen in Figure 8, which provides a comparison between the single-pulse and cross-polarization 13C MAS NMR spectroscopy results on four Cis-silica samples. Dramatic differences in line shapes and intensities, which can be interpreted at least qualitatively in terms of... 

Inorganic lattice structures have been used as surface modifications in a number of applications. In general these materials have the advantages of good stability at elevated temperatures and under oxidizing conditions combined with the potential for size, charge, or shape selectivity based upon the pores within their structures. Four types of inorganic material for surface modification have been widely studied the metallocyanates, zeolites, clays, and phosphonates. 

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