Crystal three-dimensionally ordered single

Oriented, polycrystalline specimens. If, for example, all Az = A = 0 the array would be a three-dimensionally ordered domain i.e. a "single crystal". The most highly organized fibers are ones in which many such domains are oriented with only the helix axes parallel. As I indicated above, such fibers provide X-ray diffraction patterns like those from a rotated single crystal. The not-quite-perfect parallelism of the domains causes the intensity to be distributed along arcs instead of concentrated in spots (see Fig. 2). 

This means, for example, the study of the three dimensional order on very small single crystals, phase transitions or transformations under physical or chemical factors of crystalline powders but also vitreous transition of glasses, large angle and small angle X-ray scattering (LAXS—SAXS) of amorphous phases, liquids or coordination complexes in solution. 

To set the problem of obtaining single crystal conducting polymers in perspective, R. Baughman presented a general outline of methods for obtaining three dimensional order in organic polymeric solids. Three approaches were mentioned in the discussion ... 

Associated chemical units become systematically arranged in Ihe crystal structure, which is constructed from a single motif that develops repetitively. The resulting three-dimensional array is called the space lattice of the crystal. The lattice or framework is defined by three directions and by ihe distance along those directions where the motif repeats itself. Because the units within the structure adhere lo a strict arrangement, the external facial planes of a crysial represent the limiting surfaces of that growth and are an external expression of its internal atomic order. Crystals are formed, therefore, where constituent atoms or ions are free to combine in constant chemical proportions and arc an expression of the environmental conditions that promote their formation. 

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