Three-dimensional lattice structure

Graphite is another solid form of carbon. In contrast to the three-dimensional lattice structure of diamond, graphite has a layered structure. Each layer is strongly bound together but only weak forces exist between adjacent layers. These weak forces make the graphite crystal easy to cleave, and explain its softness and lubricating qualities. 

Crystallinity. Crystals are an ordered, regular arrangement of units in a repeating, three-dimensional lattice structure. Small molecules, which in the liquid state have three-dimensional mobility, crystallize readily when cooled. It is not so easy for polymers, because a repeating unit cannot move independently of its neighbors in the chain. Nevertheless, some polymers can and do crystallize, though never completely. 

Drugs penetrate soft contact lenses at a rate that depends on the pore size between the cross-linkages of the three-dimensional lattice structure of the lens, the concentration... 

The crystalline material of type-A zeolites has a three-dimensional lattice structure of a simplified formula ... 

Although the above diagram is a simple model, this is not how it occurs in Nature. We have presented the above concept because it is easier to understand than the actual conditions which occur. It should be clear that the overall solid state reaction is dependent upon the rate of diffusion of the two (2) species, and the two rates may, or may not, be the same. The reason that A and/or B do not react in the middle, i.e.- the phase AB, is that AB has a certain ordered structure which probably differs from either A or B. But there is a more important reason which is not easily illustrated in any two-dimensional diagram, particularly since each compound has a three-dimensional lattice structure. 

The two-dimensional views illustrated in the preceding section provide a simple view of the sharing of valence band electrons and the bonds between atoms. The full three-dimensional lattice structure, however, is considerably more complex than this simple two-dimensional illustration. Fortunately, most semiconductor crystals share a common basic structure, developed as follows. 

The spheres (molecules, atoms, or ions) in a crystalline solid are arranged in a three-dimensional lattice structure consisting of a repeating pattern of unit cells. The type of unit cell is determined by the positions of the lattice points. 

This type of thickener is based on modified ureas dissolved in N-methylpyrrolidone, which are insoluble in common coating solvents. Upon careful incorporation into coating systems, the controlled precipitation of additive forms very fine, needle-like microcrystals. The crystals form a three-dimensional lattice structure via hydrogen bonding, which results in thixotropic behavior of the system. 

Ionic compounds such as sodium chloride and magnesium oxide form a giant three-dimensional lattice structure containing ions in a regularly repeating pattern. 

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