Intergrowth

The first analytical tool to assess tire quality of a zeolite is powder x-ray diffraction. A collection of simulated powder XRD patterns of zeolites and some disordered intergrowths togetlier witli crystallographic data is available from tlie IZA [4o]. Phase purity and x-ray crystallinity, which is arbitrarily defined as tlie ratio of tlie intensity of... 

Cell Chemistry. Work on the mechanism of the carbon—2inc cell has been summari2ed (4), but the dynamics of this system are not entirely understood. The electrochemical behavior of electrolytic (FMD), chemical (CMD), and natural (NMD) manganese dioxide is slightly different. Battery-grade NMD is most commonly in the form of the mineral nsutite [12032-72-3] xMn02, which is a stmctural intergrowth of the minerals... 

An interesting type of clay used widely in the manufacture of refractories is so-called flint clay, which is very hard and has very slight plasticity even when finely ground. Flint clays are essentially pure, extremely fine-grained kaolinite. In some cases the hardness appears to result from the presence of a small amount of free siUca acting as a cement, whereas in other cases it is the result of an intergrowth of extremely small kaolinite particles. 

A) A stacking disorder (De Wolff disorder intergrowth of ramsdellite- and pyrolusite- type units, as already described above). This kind of disorder can be quantified by two parameters ... 

The metaUic GasIngSrig can be described a an intergrowth of Zintl and metalHc layers, where the valence states of the Zintl layers lie deep below the Fermi level. The excellent metalHc behavior of Ga5ln9Sng was attributed to the well-dispersed electronic states of the intermetallic layers that dominate the Fermi level. 

Definition An intergrowth of two or more macroscopic individuals of the same crystal species is a twin, if the orientation relations between the individuals conform to crystallographic laws. The individuals are called twin partners, twin components or twin domains. 

On the intergrowth structure of zeolite crystals as revealed by wide field and confocal fluorescence microscopy of the template removal processes... 

Keywords zeolites fluorescence confocal fluorescence microscopy template removal intergrowth... 

Figure 3. Exploded and normal representation of the proposed intergrowth structures of the zeolite crystals under study a) CrAPO-5 (front subunits are not shown) b) SAPO-34 c) SAPO-5 (front subunits are not shown) and d) ZSM-5.

It was proposed that a further nucleation process occurs at the interface between the central and outward components, making the boundary between them defect-rich. These discontinuities in the crystalline structure and in the porous network are not sufficiently large to be directly noticeable by optical microscopy or SEM [18], nevertheless it allows us to visualize the internal intergrowth structure. 

Unlike crystals that are packed with identical unit cells in 3D space, aperiodic crystals lack such units. So far, aperiodic crystals include not only quasiperiodic crystals, but also crystals in which incommensurable modulations or intergrowth structures (or composites) occur [14], That is to say, quasiperiodicity is only one of the aperiodicities. So what is quasiperiodicity Simply speaking, a structure is classified to be quasiperiodic if it is aperiodic and exhibits self-similarity upon inflation and deflation by tau (x = 1.618, the golden mean). By this, one recognizes the fact that objects with perfect fivefold symmetry can exist in the 3D space however, no 3D space groups are available to build or to interpret such structures. 

Figure 6. High-resolution micrograph together with corresponding scalar structural drawing, computed image, and appropriate diffraction pattern showing structural resolution of BigWgOg with some Bi2W3012 intergrowths (24).

Figure 3. Schematic illustration of the disposition of chains made up of cornersharing SiOk tetrahedra in the triclinic and monoclinic forms of wollastonite, (The Ca2+ ions have been omitted for clarity) (top), and (hOl) and (hll) x-ray diffraction patterns that signify that the specimen in question is disordered and made up of intergrowths of the triclinic and monoclinic forms (bottom).

The transmission electron microscopy (TEM) images of a two-layer Tl-1223 film are shown in Fig. 7.12, which confirms the epitaxial nature of the annealed electrodeposited films. All films showed a significant amount of intergrowth, as shown by a high-resolution transmission electron microscopic (HRTEM) measurement in Figs. 7.12c and d of a representative two-layer... 

In the previous sections composition variation has been attributed more or less to point defects and extensions of the point defect concept. In this section structures that can be considered to be built from slabs of one or more parent structures are described. They are frequently found in mineral specimens, and the piecemeal way in which early examples were discovered has led to a number of more or less synonymic terms for their description, including intergrowth phases, composite structures, polysynthetic twinned phases, polysomatic phases, and tropochemical cell-twinned phases. In general, they are all considered to be modular structures. 

---