Subcell arrangements

Fig.1. (A) Three typical subcell arrangements and (B) four typical chainlength structures.

FIGURE 3.15 Circuit diagram of the main cell subcell arrangement. L, Li, and L4 denote the loadbanks for the main cell and the subcells, respectively. Additional sensing wires (two for each subcell) are omitted for clarity [56]. 

Figure 1. Extended unit cell finite element models hexagonal arrangement and detail of center subcell (left) square edge arrangement and detail of center subcell (middle) random arrangement (right)...

It will be realized from fig. 8.21 that if the X ions alone are considered the positions of these ions could be described in terms of a cubic subcell of volume only one-eighth that of the true cell, with the X ions at its corners and face centres. In other words, the structure is one in which the X ions are arranged as in cubic close packing, with the A and B ions in the tetrahedrally and octahedrally co-ordinated interstices, respectively. 

Systematic extinctions of OkZ reflections with I 2n are characteristic of the diffraction pattern of Mn Sl . The extinction law and the symmetry of the arrangement of manganese atoms in the subcell enable the compound to be placed with certainty in the D%i — PA[Pg.4]

Although the effect of the mutual arrangement of the molecules in a subcell on the CH stretching bands has been found to be negligible [507, 527], the ratio of the band intensities can be used for determining the film symmetry [558] (see Section 3.11.3 for details). 

The packing arrangement of hydrocarbon chains can be described by the so-called subcell, which is the smallest crystallographic unit in a hydrocarbon chain layer. By lateral repetition of the subcell, the... 

The crystal structure of the B-form of stearic acid (von Sydow, 1955) is shown in Fig. 8.27. The molecules are arranged in an orthorhombic chainpacking structure, in bilayers. The orientation of the chain-packing subcell in relation to the methyl end group planes is Oi (101) (see Section 8.1). A modified B-form was observed in 11-bromoun-decanoic acid (Larsson, 1963a) which was termed Bi. It is isomorphous with the B-form according to X-ray diffraction data, but the OH-out-of-plane vibration in the infrared absorption spectra is different. A new form of stearic acid (Holland and Nielsen, 1963), described according to infrared absorption data, appears to be the same form as Bi in 11-bromoundecanoic acid. As the first crystal... 

The crystal structure of the C-form of lauric acid was the first fatty acid structure determined (Vand et al., 1951). The structure is of the usual bilayer type with the chains arranged to the orthorhombic chain packing. The structure of the C -form of undecanoic acid has also been determined (Fig. 8.30) (von Sydow, 1956b). It is strictly isostructural with that of the C-form. The molecular arrangement in the bilayer is thus the same with the end group plane related to the chain-packing subcell according to O i (021). 

The C -form was found to have the carbon atoms located in a distorted way with regard to the planar zig-zag conformation. Also the dimensions of the orthorhombic subcell indicates an intermediate arrangement towards hexagonal chain packing. This is certainly a consequence of the existence of the C -form in a narrow temperature range close to the melting point. Similar disorder effects in the C-form close to the melting point were discussed in Section 8.1. 

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