Lattice types, crystal

Shown below are commonly encountered crystal lattice stmctures. The lattice type depends on the radius ratio favoring a particular coordination number for the stmcture type. 

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Table 4.14 Spatial Orientation of Common Hybrid Bonds Figure 4.1 Crystal Lattice Types Table 4.15 Crystal Structure...

Cellulose Crystallinity and Crystal Lattice Type, Part II, J. Appl. Polym. Sci. (1964) 8, 1325-1341. 

Figure 2.2. Close Packing of Atoms Crystal Lattice Types...

The results of the application of these calculations to various types of crystal are discussed below. Table II summarizes the values of Madelung constants obtained for different crystal lattice types. The general formulae which have been developed to express the Madelung constants as functions of various lattice parameters and the variation of Madelung constants with crystal parameters are discussed in more detail below. 

AZMEP-n. n=odd. Fiber diffraction patterns from single filaments of the AZMEP-n polymers with an odd number of methylene units in the backbone (n = 2k-1, k = 1-8) indicate that the polymers can have high crystallinity with good to moderate orientation. Unit cell parameters derived from the diffraction data are listed in Table II. The odd AZMEP-n s can be divided into three distinct groups on the basis of the crystal lattice type ... 

There is a wealth of crystal lattice types of interest in this review. We can differentiate between solid CT complexes and ion-radical salts. The former are the solid-state equivalents of the Mulliken solution CT complexes, and are the "two-chain" crystals. The latter are the so-called "one-chain" compounds, or ion-radical salts, where the organic cation (anion) crystallizes with inorganic anions (cations) as counterions. The crystal structure types have been reviewed by Herbstein [61], Tanaka [62], Soos [63-65] and many others. TaWes 1 and 2 update a classification introduced by Soos [63] and modified later by Wiygul et al. [66]. A few examples are shown diagrammatically in Fig. 4. The IS lattices are the ion-radical salts the IM lattices are the CT crystals, the crystal equivalents of the solution CT complexes. The 2S lattices are the first organic metals found (TTF-TCNQ). 

Table 3.10 Crystal lattice types of several metal oxides...

The degree of molecular orientation, that is, degree of crystallinity, of natural products is also dependent on the source of the products. For example, cellulose in cotton fiber has a degree of crystallinity of about 80 percent. Celluloses from other sources are less molecularly oriented. The degree of molecular o-rientation in cellulose as well as crystal lattice type... 

Since the number of slip systems is not usually a function of temperature, the ductility of face-centered cubic metals is relatively insensitive to a decrease in temperature. Metals of other crystal lattice types tend to become brittle at low temperatures. Crystal structure and ductility are related because the face-centered cubic lattice has more slip systems than the other crystal structures. In addition, the slip planes of body-centered cubic and hexagonal close-packed crystals tend to change at low temperature, which is not the case for face-centered cubic metals. Therefore, copper, nickel, all of the copper-nickel alloys, aluminum and its alloys, and the austenitic stainless steels that contain more than approximately 7% nickel, all face-centered cubic, remain ductile down to the low temperatures, if they are ductile at room temperature. Iron, carbon and low-alloy steels, molybdenum, and niobium, all body-centered cubic, become brittle at low temperatures. The hexagonal close-packed metals occupy an intermediate place between fee and bcc behavior. Zinc undergoes a transition to brittle behavior in tension, zirconium and pure titanium remain ductile. 

Nelson, M. L. O Connor, R. T. (1964). Relation of Certain Infrared Bands to Cellulose Crystallinity and Crystal Lattice Type. Part II. A New Infrared Ratio for Estimation of Crystallinity in Celluloses I and IT Journal of Applied Polymer Science, 8, 1325-1341. 

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