Boron crystal structures, lattice parameters

Figure 2. Schematic sketch of the graphite (a) and boron nitride b) crystal structures including the lattice parameters.

FIGURE 7.8 The crystal structure of tourmaline. The 3-fold axis can be seen. The lattice parameters are a = 1.58 and c = 0.71 nm. Most of the nominal 140 atoms in the oell sit in tetrahedral or octahedral sites, but the important boron ion sits at the center of three planar anions. 

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